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CYTOTOXICITY OF QMix™ ENDODONTIC IRRIGATING SOLUTION ON HUMAN BONE
MARROW MESENCHYMAL STEM CELLS
&
COMPARISON OF DIGITAL AND CONVENTIONAL IMPRESSION TECHNIQUES:
EVAUATION OF PATIENTS’ PERCEPTION, TREATMENT COMFORT, EFFECTIVENESS
AND CLINICAL OUTCOMES
&
HOW NOT TO OVERWORK YOUR HANDS
&
CURRENT FLUORIDE MODALITIES FOR REDUCTION OF DENTAL CARIES
Approved for 4 CLINICAL Continuing Educational Units
AlKahtani et al. BMC Oral Health 2014, 14:27
http://www.biomedcentral.com/1472-6831/14/27
RESEARCH ARTICLE
Open Access
Cytotoxicity of QMix™ endodontic irrigating
solution on human bone marrow mesenchymal
stem cells
Ahmad AlKahtani1*, Sarah M Alkahtany1, Amer Mahmood2, Mona A Elsafadi2, Abdullah M Aldahmash2
and Sukumaran Anil3
Abstract
Background: Debridement and disinfection of the root canal system is a crucial step in endodontic procedures.
The effectiveness of irrigation relies on both the mechanical flushing action and the ability of irrigants to dissolve
tissue and kill bacteria. The objective of the present study is to evaluate and compare the cytotoxicity of QMix™
root canal irrigating solution on immortalized human bone marrow mesenchymal stem cells (hTERT-MSC-C1) and
to compare it with that of sodium hypochlorite (NaOCl).
Methods: Immortalized human bone marrow mesenchymal stem cells (hTERT-MSCs) were exposed to QMix™ and
NaOCl. Cell viability was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and alamarBlue
assays. The cell morphology was studied after two hours of exposure to QMix™ and NaOCl. Scanning electron microscopy
(SEM) analyses were performed after 2- and 4-hour incubation periods. Finally, ethidium bromide/acridine orange (EB/AO)
fluorescent stain was applied to the cells in the 8-chamber slides after they were incubated with the testing agents for 2
hours to detect live and dead cells. The observations were tabulated and analyzed statistically.
Results: QMix™ exposure resulted in a significantly higher percentage of cell viability than NaOCl in the MTT and
alamarBlue assays at three time points compared to the control. The SEM analysis demonstrated minimal morphological
changes associated with cells that were exposed to the QMix™ solution, with little shrinkage and fragmentation of the cell
wall. The live/dead analysis showed that the number of live cells after exposure to QMix™ was similar to that of the
untreated control. No cell structure could be observed with the NaOCl group, indicating cell lysis.
Conclusion: Both the QMix™ and NaOCl solutions were toxic to human bone marrow MSCs. Each solution might have
induced cell death in a different way as evidenced in the cell viability, SEM and fluorescent studies. The slower cell death
induced by QMix™ might therefore be less aggressive and more acceptable to living tissues.
Keywords: Cytotoxicity, Sodium hypochlorite, QMix™, Mesenchymal stem cells, Root canal irrigants
Background
The success of endodontic therapy depends on the eradication of microbes from the root canal system and the subsequent prevention of reinfection. Root canal irrigation has a
key role in the success of endodontic treatment. During
and after instrumentation, irrigants facilitate the removal
of microorganisms, tissue remnants, and dentin chips from
the root canal through a flushing mechanism [1,2].
* Correspondence: [email protected]
1
Department of Restorative Dental Sciences, College of Dentistry, King Saud
University, Post Box 60169, Riyadh 11545, Saudi Arabia
Full list of author information is available at the end of the article
An ideal root canal irrigant solution should be nontoxic,
with a broad antimicrobial spectrum and the ability to dissolve necrotic pulp tissue, inactivating endotoxins, and either prevent the formation of a smear layer or dissolve it
[3,4]. Currently, no single solution is able to achieve these
goals, and the combined, concomitant or sequential use of
two or more irrigating solutions is thus required [5]. Sodium hypochlorite (NaOCl) and chlorhexidine digluconate
(CHX) are two common antibacterial agents used as root
canal irrigants [5-7].
© 2014 AlKahtani et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain
Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article,
unless otherwise stated.
AlKahtani et al. BMC Oral Health 2014, 14:27
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Currently, sodium hypochlorite (NaOCl) (0.5–6.15%)
and EDTA (15–17%) are the two most commonly used
intracanal irrigants [5,8]. Although sodium hypochlorite
has most of the desirable properties, it also can produce
cytotoxicity and severe inflammatory reactions [9,10]. Ethylenediaminetetraacetic acid (EDTA) is effective for removing the inorganic component of the smear layer [11].
However, due to undesirable outcomes, a combination of
these irrigants is not advisable [12-15]. Hence, the sequential use of EDTA, CHX and NaOCl has been advocated by
many researchers to produce optimal root canal irrigation
results [16-18]. It is imperative that the root canal irrigants
must not hamper the healing process of the apical region.
The biocompatibility of these materials is important, as
they come into contact with the peri-radicular tissues.
QMix™ is a 2-in-1 solution containing a bisbiguanide
antimicrobial agent (2% CHX) and a polyaminocarboxylic
acid calcium-chelating agent (17% EDTA) [19]. QMix™
was found to be effective in removing the smear layer and
also has substantial antimicrobial properties [19-22]. However, data regarding the cytotoxicity of this agent are not
available. Hence, the present study was conducted to
evaluate and compare the cytotoxicity of the QMix™
irrigating solution on immortalized human bone marrow
mesenchymal stem cells (hTERT-MSC-C1) using cell viability assays, cell morphology evaluation, and fluorescence
light microscopy; 5.2% NaOCl was used for comparison.
Methods
The study was approved by the Departmental review
board of College of Dentistry Research Centre, king Saud
University, Riyadh.
Test solutions
QMix™2-in-1 (Dentsply Tulsa Dental, OK, USA) and
5.25% NaOCl (Clorox Co., Oakland, CA, USA) were
used in this study.
Cell culture
Immortalized human bone marrow mesenchymal stem
cells (hTERT-MSC-C1), at the 25th passage, were used for
all experiments in this study. The protocol of Simbula et al.
[23] was used in this study, with some modifications. The
human bone marrow mesenchymal stem cells were provided by Professor Moustapha Kassem at the Odense University Hospital, Denmark [24]. The cryopreserved cells
were rapidly thawed, transferred into a T-75 flask (BD Falcon™, NJ, USA) and cultured in Dulbecco’s modified Eagle’s
medium (Gibco®), which was supplemented with glutamine
(Gibco®), 1% penicillin-streptomycin (Gibco®), 10% fetal bovine serum (FBS Gibco®), and 1% non-essential amino acids
(HyClone®), in a humidified atmosphere of 5% CO2/95% O2
at 37°C. At 70% confluence, the medium was aspirated, and
the cells were washed with phosphate-buffered saline.
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Three milliliters of pre-warmed 0.05% trypsin/EDTA
(Gibco®) was added to the flask, and the cells were incubated for 1 minute. After gentle tapping, cell detachment was checked under an inverted light microscope
(Observer A1, Zeiss®, Gottingen, Germany), and 12 ml of
culture media was then added to the flask to neutralize
the enzymatic effect of trypsin. For cell counting, two samples (10 μl) were taken from the cell suspension after appropriate mixing. The samples were placed in the upper
and lower chambers of a Neubauer hemocytometer
counting chamber (Paul Marienfeld GmbH & Co. KG,
Lauda-Königshofen, Germany), and the cells were counted
manually under an inverted microscope (10X magnification). The cells were seeded on different plates and slides,
as discussed below, for each part of the study. All procedures were performed under a class II laminar flow hood
(LabGard ES 425 Biological Safety Cabinet, NuAire®).
MTT cell viability assay
Cells were seeded in 96-well plates (clear, flat bottom, Polystyrene TC-Treated 96-well microplates) at a concentration
of 1 × 104 cells/well and were then incubated for 24 hours
to allow cell adherence to the bottom of the wells. Culture
media were then aspirated from each well and replaced
with 150 μl of sterile solution (QMix™ or NaOCl). Eight
wells were used as replicates for each group.
Each subgroup was incubated for the following periods:
2, 4, or 24 hours. Then, 10 μl of the MTT reagent (Cayman
Chemical Company, Ann Arbor, MI, USA) was added to
each well. Thereafter, 96-well plates were further incubated
for 3 hours at 37°C. Finally, the solution from each well was
aspirated, and 150 μl of dissolving agent was added to dissolve the formazan precipitate. The absorbance of each
sample was measured with a microplate reader (Epoch
Microplate Spectrophotometer, BioTek®) at a wavelength of
570 nm. The data were gathered using Gen5 Data Analysis
Software (BioTek®, USA). The experiment was repeated
twice for each group in each interval.
AlamarBlue (AB) cell viability assay
The same groups that were used for the MTT assay
(mentioned above) were used for the AB assay with the
same intervals. The test agents were added to each well.
After 2-, 4-, and 24-hour incubation periods, 10% AB
reagent (Serotec®, Oxford, UK) was added to each well.
After the plates were further incubated for 4 hours, the
fluorescence of each well was measured at wavelengths
of 530/25 and 590/35 nm excitation/emission using a
fluorescence reader (BioTek®). The data were gathered
using the Gen5 Data Analysis Software (BioTek®, USA).
The experiment was repeated twice for each group in
each interval.
AlKahtani et al. BMC Oral Health 2014, 14:27
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Cell morphology assessment
Cell morphology was evaluated with SEM after 2 and 4
hours of exposure to the test solutions. Briefly, 8 × 104
cells/well were seeded onto glass cover slides (1 × 1.5
cm) in 6-well plates (CellStar®, Carrollton, TX) overnight. The next day, the cells were exposed to the test
solutions. Two milliliters of each sterile irrigation
solution was added to the slides in each well. Control
untreated cells were maintained in culture medium. Immediately after the test solutions were added, the cells
were examined under an inverted LM (10x magnification). At the end of the incubation periods (2 and 4 hrs),
the solutions in each well were aspirated. The slides
were washed with PBS and were then fixed with 2.5%
glutaraldehyde in 0.1 M Na cacodylate buffer (pH 7.2) at
room temperature. Thereafter, the specimens were
washed with 0.1 M sodium cacodylate buffer (pH 7.2).
After fixation, the specimens were treated with 1% osmium tetroxide for 1 hour. Then, they were washed with
distilled water and dehydrated using graded ethyl alcohol,
in concentrations of 50%, 70%, 80%, 90% (5 minutes each),
95% (twice, 15 minutes each), and finally, 100% absolute alcohol (twice, 30 minutes each). The specimens were dried
using a critical point dryer with CO2 (SADRI-PVT-3B).
Slides were mounted on copper stubs with double adhesive
tape and were then gold sputter coated to a thickness
of 5–7 μm. The specimens were then observed and
photographed using a JSM-6360 LV scanning electron
microscope.
Two evaluators assessed the photomicrographs. The cell
morphology was described according to the following criteria: the shape of the cell (normal or abnormal compared
with the control), attachment to the subsurface, attachment to other cells, cytoplasmic surface extensions (blebs
or microvilli), and cell wall integrity. Roundness of the
cells, the presence of blebs, or detachment of the cells indicated greater cell injury [25,26].
Page 3 of 9
bromide powder that was first dissolved in 1 ml 95% ethanol and then diluted in 49 ml of distilled water (dH2O).
The images were evaluated by two evaluators according
to previously described criteria. Under the green filter, an
intact green nucleus, which is comparable to the control,
indicates a viable cell, whereas a green fragmented nucleus
indicates early apoptosis. A red nucleus indicates a ruptured
cell wall, whereas a red intact nucleus indicates necrosis,
and a fragmented red nucleus indicates late apoptosis under
the red filter [27,28].
Data and statistical analysis
The results of the MTT and AlamarBlue assays were calculated as percentages relative to the control (100% = no
toxicity). The data were analyzed using SPSS Pc + version
21.0 statistical software. Descriptive statistics (mean and
standard deviation) were used to describe continuous outcome variables. Student’s t-test for independent samples
was used to compare the mean values of two groups. A
one-way analysis of variance, followed by a multiple comparison Tukey’s test, was used to compare the mean values
of the three groups. A p-value of < = 0.05 was considered
statistically significant.
Results
MTT assay
The MTT assay was conducted on three groups (the
QMix™ group, NaOCl group, and Control group) with
cultured hTERT-MSCs in 96-well plates. Each group was
incubated for 2, 4 and 24 hours. The cell viability for
each group is presented as percentage of the control
group at each time point. The percentage cell viability of
each solution is illustrated in Figure 1. When the cells
were exposed to solutions for 2, 4 and 24 hours, the cell
viability decreased with time. The viability of cells exposed NaOCl was significantly lower than that of cells
exposed to QMix™ at all time intervals (P < 0.05).
Live/dead analysis
AlamarBlue assay
Two solutions were selected for the live/dead analysis. A
modified Eagle’s medium (MEM) without phenol red
(Gibco®, Gaithersburg, MD) was used for this experiment.
Briefly, cells were seeded in three 8-chamber slides (LabTek®) at a concentration of 1.5 × 104 cells/well and were
then incubated for 24 hrs to allow cell adhesion to occur.
The culture medium in each well was replaced with 300 μl
of each solution and then incubated for 2 hrs. Finally, 10
μl of EB/AO fluorescent dye was added to each chamber,
and the fluorescence of the cells was analyzed under a
fluorescent inverted microscope (ECLIPSE Ti, Nikon,
Tokyo, Japan), with 10X magnification. Images were captured with imaging software (NIS-Elements, Nikon,
Tokyo, Japan). The EB/AO fluorescent dye was prepared
by mixing 15 mg acridine orange with 50 mg ethidium
The AB assay was conducted for the QMix™, NaOCl and
Control groups using cultured hTERT-MSCs in 96-well
plates. The cell viability for each group is presented as the
percentage of the control group. The cell viability percentage of each solution is illustrated in Figure 2. When the
cells were incubated for 2 or 4 hrs, the cell viability of the
NaOCl group was significantly lower than that of the
QMix™ group (P < 0.05).
Cell morphology
Untreated negative control cells showed variable shapes,
including rhomboid, triangular, oval and spindle shapes, as
illustrated by light microscopy LM (Figure 3) Cells were
attached to each other and to the substrate. The cell wall
appeared smooth and intact, with some microvilli and
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Figure 1 The cell viability percentage for NaOCl and QMix
solutions at 2, 4 and 24 hours after exposure using MTT assay.
surface extensions. According to the LM investigation, the
toxic effect of the test solutions was evident immediately
after their application to the cultured human bone marrow MSCs, and the normal cell morphology was altered
differently in each group (Figure 3). A high concentration
(0.5 mg/ml) of NaOCl caused the vacuolization of the
cytoplasm (Figure 3B), whereas QMix™ at the same concentration produced few alterations in the cell wall and no
vacuolization (Figure 3C).
Figure 3 Human bone marrow hTERT-MSCs under inverted LM
after adding the testing agents (X10). A- Untreated cells, B - Cells
exposed to (0.5) Qmix™ solution (the cell shape was maintained with
few alterations), C- Cells exposed to (0.5) NaOCl; vacuolization was
evident in the cytoplasm.
Figure 2 The cell viability for both NaOcl and QMix™ solutions
using alamarBlue assay at 2, 4 and 24 hours of exposure.
According to the SEM analysis, the cell number decreased relative to the control after a 2-hour exposure
to 0.5 mg/ml NaOCl. The remaining cells were smaller,
with a thread-like or round shape (Figure 4). Cells became detached from the subsurface, and cell-to-cell attachments were lost. Lysosomal secretions emerging
AlKahtani et al. BMC Oral Health 2014, 14:27
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Figure 4 Human bone marrow hTERT-MSCs exposed for 2 hrs to QMix and NaOCl. A - QMix™ (x100), B - QMix™ (x1000), C - NaOCl (x100,
note the round or thread-like shape of the remnant cells), D- NaOCl (x1000, the ruptured cell wall and the extruded nucleus).
from the cell were observed, and the nucleus was extruded through the ruptured cell wall.
After a 2-hour exposure to QMix™, the cell number and
cell shape were similar to those of the control, except for
the presence of an ill-defined cell outline. However, the
cells were still attached to adjacent cells and to the substrate (Figure 4). In some areas, remnants of cell processes
were observed. The main dramatic change in the cell
morphology was in the cell wall, which had a mesh-like
appearance (Figure 4B), indicating disintegration. After 4
hours, the alteration of cell morphology was more significant: the mesh-like appearance of the cells became more
intense, with an ill-defined shape and a fading outline, and
broken cell-to-cell attachments were observed. However,
the attachment to the substrate was maintained by some
cells (Figure 5).
Live/dead analysis with EB/AO staining
Cultured human bone marrow hTERT-MSCs were exposed to 0.5 mg/ml of QMix™ and NaOCl for 2 hrs. The
EB/AO stain was applied to the cells, which were then examined under an inverted fluorescence microscope. The
images for each group display live cells in green and dead
cells in red. The untreated cells had intact, well-defined
nuclei, which were green under the green filter, as shown
in Figure 6A. Under the red filter, only the cell surface
showed red fluorescence, not the nucleus, which indicated
an intact cell wall (Figure 6B). When the cells were
exposed to QMix™, the cell number was similar to that
of the control group, and the nuclei were green, which
was similar to the appearance of the control cells. The
only difference was that some of these cells had condensed chromatin, which was evident under the red filter (Figure 6C, D). When the cells were exposed to
NaOCl, no cell structures, such as the nucleus or cell
membrane, were observed; cell lysis was evident, and
the remnant material was positive for both green and
red fluorescence (Figure 6E, F).
Discussion
This in vitro study was conducted to assess the cytotoxicity of the QMix™ irrigating solution on human bone
marrow MSCs. MSCs have been suggested as a good
model for toxicological testing [29]. The MSCs that were
used in this study were immortalized by the ectopic expression of human telomerase reverse transcriptase (hTERT), which increased the life span of the cells [24]
and maintained their stem-like properties [30]. Earlier
studies have reported that immortalized cells can be
used as a test model for dental materials [31].
The observations from the study showed that both solutions (QMix™ and NaOCl) are toxic to human bone marrow MSCs and cause cellular damage. This is consistent
with the results of previous studies that reported on
NaOCl toxicity [23,32,33]. NaOCl toxicity can be attributed to its high pH (hydroxyl ion action), which interferes
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Figure 5 Human bone marrow hTERT-MSCs exposed for 4 hrs to QMix™ and NaOCl. A- QMix™ (x100), B-QMix™ (x1000), C - NaOCl (x100),
D- NaOCl (x1000).
with cytoplasmic membrane integrity [34]. Furthermore,
our results are in agreement with those of a previous
in vivo study, which found that QMix™ is toxic and can induce an inflammatory response [35]. CHX is a toxic agent
that binds to the cell’s plasma membrane and increases its
permeability, allowing the leakage of lysosomal enzymes
[36]. EDTA, which is the second QMix™ component, is
also known to be cytotoxic, perhaps due to its chelating
effect and the accentuated drop in pH that it causes [11].
Cell viability decreased significantly when the cells were
exposed to NaOCl for all time periods examined. Cell
viability decreased significantly after being exposed to the
QMix™ solution for 2 or 4 hours. Moreover, after 24 hours,
cell viability was significantly decreased compared to 2
and 4 hours of exposure. These findings show that the
toxic effect of an agent gradually increases with time. This
observation is in agreement with those of previous studies,
confirming that toxicity is time dependent [37]. In contrast, the MTT assay results showed a significant decrease
in the cell viability of cells that were exposed to NaOCl at
all time periods examined. Compared with QMix™exposed cells, NaOCl decreased viability at 2 and 4 hours .
Previous studies have reported that the AB assay is
slightly more sensitive than the MTT assay. However, both
assays rely on enzymatic metabolism, which may be inhibited or induced by the testing agent, thus producing a
false-positive or false-negative result. Therefore, careful interpretation of the results is always recommended [38].
Our observations suggest that the AB assay is a better
choice for cell viability testing because it is easy to perform, more consistent than the MTT assay, and recommended by previous studies [38,39]. However, it is always
recommended to use more than one assay to assess cytotoxicity. Therefore, previous studies that relied solely on
the MTT assay should be re-evaluated and interpreted
with caution.
Microscopic morphological investigations are necessary
to confirm cellular toxicity [40]. This is because a cell can
undergo toxic changes, such as detachment, while still
continuing to metabolize MTT to formazan, resulting in
an over estimation of cell viability in the MTT assay compared with the AB assay [38]. Therefore, cellular morphological characteristics were investigated for both solutions.
Cells that were exposed to QMix™ displayed fewer morphological alterations. This observation is in agreement
with Faria et al., who reported that higher concentrations
of CHX would preserve the shape of the L929 cells [41]
due to its cell fixation effect [42].
The SEM images for the QMix™ group showed cytoplasmic shrinkage with partially fragmented but intact
cell walls. These characteristics are typical of apoptosis,
as reported previously [40]. In addition, the EB/AO
staining showed bright green fragmented nuclei, indicating early apoptosis [27]. The cells exposed to NaOCl
had cytoplasmic shrinkage or ruptured membranes, which
are typical characteristics of necrosis [43]. The EB/AO
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Figure 6 Live/dead analysis human bone marrow hTERT-MSCs under a fluorescence microscope (X10). 6A, 6B – Untreated cells with the
green filter, the nucleus appears intact , which indicates a viable cell. 6B-with the red filter, the nucleus appeared dark, and only the external surface of
the cells was red, indicating that the cell wall is intact. 6C, 6D- treated with QMix™ under a fluorescence microscope (X10), 6E,6F- treated with NaOCl
under a fluorescence microscope (X10).
staining of the NaOCl group displayed red and green,
reflecting remnant material that may be the result of cell
lysis, and no cell structure could be observed. The overall
analysis of these results suggests that the cells in the
QMix™ groups are in the early stages of apoptosis but are
not yet dead, in contrast to the NaOCl group. Both NaOCl
and QMix™ are cytotoxic; however, it seems that their
mode of cell killing differs as a result of their different
compositions. According to Galluzzi et al. [44], cell death
can be classified into four different types based on the
morphological characteristics of the dying cells: apoptosis
(Type 1), autophagy (Type 2), necrosis (oncosis, Type 3),
and mitotic catastrophe. Each mode of cell death has its
own function; necrosis induces an inflammatory response
when it is needed, whereas apoptotic cells in vivo are rapidly phagocytosed without inducing an inflammatory response, which is considered a mechanism for avoiding
immune activation. According to our findings, this mode
of cell death could be associated with a high concentration
exposure to NaOCl.
Apoptosis is an active form of cell death known as programmed cell death, and it is characterized by cell shrinkage and the nuclear chromatin condensation followed by
nuclear fragmentation, with the normal morphological appearance of cytoplasmic organelles and the maintenance of
an intact plasma membrane [44]. According to our
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findings, this mode of cell death could be associated with
QMix™ exposure. However further markers such as detection of caspases, cleaved substrates, regulators and inhibitors are necessary to substantiate this mode of cell death
speculated with QMix™ [45]. Cell death through apoptosis
is known to occur through two primary pathways: an
extrinsic pathway that involves death receptors, and an
intrinsic pathway that is modulated by members of the
Bcl-2 family [46], which consists of outer mitochondrial
membrane components [47]. Therefore, mitochondria are
considered key organelles in the pathways to cell death in
addition to its normal metabolic activity [48,49]. However,
these proteins may also function in some normal metabolic
pathways. Thus, mitochondrial metabolic activity investigations, such as the MTT assay, must consider these potential overlaps between pre-apoptotic cell activity and normal
cell metabolism [40]. This overlap could explain the
contradictory results of the AB and MTT assays.
In vitro cytotoxicity investigations reported that CHX
had a higher toxicity in cell cultures than NaOCl [33,41].
However, in vivo studies suggest that CHX or QMix™ is
less aggressive than NaOCl [35,50]. This difference could
be attributed to host defense mechanisms that operate in
the in vivo environment.
Our in vitro study has the following limitations: it was
conducted on cultured cells, and the results represent only
the response of these cells in isolation, without taking into
account the host defense mechanism for detoxification.
Furthermore, in a clinical setting, the solutions are always
delivered to root canals, which are surrounded by dentine,
and are then extruded to the periapical area. Previous
studies have reported that the cytotoxic effect of irrigants
can be neutralized by dentine [33,51]. We placed the solutions directly onto the cells, and no attempts were made
to deliver these solutions through root canals to mimic
the clinical scenario.
Conclusions
Within the limitations of this study, it can be concluded
that both the NaOCl and QMix™ solutions are toxic to human bone marrow MSCs. The QMix™ solution, which induces slow cell death, seems to be more biocompatible
than the NaOCl solution. Hence, based on these observations, it can be concluded that the QMix™ is a relatively
safer root canal irrigant compared to NaOCl.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
AK, SMA, AM and MAE carried out the study, laboratory procedures and
evaluation of the results. SA, AK and AMA involved in the development of
the concept, design of the study, revision of the manuscript and statistical
analysis. All authors read and approved the final manuscript.
Page 8 of 9
Author details
1
Department of Restorative Dental Sciences, College of Dentistry, King Saud
University, Post Box 60169, Riyadh 11545, Saudi Arabia. 2Stem Cell Unit,
Department of Anatomy College of Medicine, King Saud University, P.O. Box
2925, Riyadh 11461, Saudi Arabia. 3Department of Periodontics and
Community Dentistry, College of Dentistry, King Saud University, Riyadh, Post
Box 60169 11545, Saudi Arabia.
Received: 18 February 2014 Accepted: 25 March 2014
Published: 29 March 2014
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damage after sodium hypochlorite extrusion during root canal treatment.
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15. Basrani BR, Manek S, Sodhi RN, Fillery E, Manzur A: Interaction between
sodium hypochlorite and chlorhexidine gluconate. J Endod 2007,
33(8):966–969.
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Friedman S: Substantive antimicrobial activity in chlorhexidine-treated human
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19. Dai L, Khechen K, Khan S, Gillen B, Loushine BA, Wimmer CE, Gutmann JL,
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The effect of the irrigant QMix on removal of canal wall smear layer: an
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Yuzbasioglu et al. BMC Oral Health 2014, 14:10
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RESEARCH ARTICLE
Open Access
Comparison of digital and conventional
impression techniques: evaluation of patients’
perception, treatment comfort, effectiveness and
clinical outcomes
Emir Yuzbasioglu*, Hanefi Kurt, Rana Turunc and Halenur Bilir
Abstract
Background: The purpose of this study was to compare two impression techniques from the perspective of
patient preferences and treatment comfort.
Methods: Twenty-four (12 male, 12 female) subjects who had no previous experience with either conventional or
digital impression participated in this study. Conventional impressions of maxillary and mandibular dental arches
were taken with a polyether impression material (Impregum, 3 M ESPE), and bite registrations were made with
polysiloxane bite registration material (Futar D, Kettenbach). Two weeks later, digital impressions and bite scans
were performed using an intra-oral scanner (CEREC Omnicam, Sirona). Immediately after the impressions were
made, the subjects’ attitudes, preferences and perceptions towards impression techniques were evaluated using a
standardized questionnaire. The perceived source of stress was evaluated using the State-Trait Anxiety Scale.
Processing steps of the impression techniques (tray selection, working time etc.) were recorded in seconds.
Statistical analyses were performed with the Wilcoxon Rank test, and p < 0.05 was considered significant.
Results: There were significant differences among the groups (p < 0.05) in terms of total working time and
processing steps. Patients stated that digital impressions were more comfortable than conventional techniques.
Conclusions: Digital impressions resulted in a more time-efficient technique than conventional impressions.
Patients preferred the digital impression technique rather than conventional techniques.
Keywords: Digital impression, Clinical efficiency, Patient comfort, Patient preference
Background
The introduction of computer-aided design/computer
aided manufacturing (CAD/CAM) technology in dentistry has resulted in more accurate manufacturing of prosthetic frameworks, and greater accuracy of dental
restorations, and the technology has improved since the
1980s [1,2]. The development strategy of CAD/CAM
techniques included automating the production process
and optimizing the quality of restorations by using new
biocompatible materials, especially high performance
ceramics, such as zirconia and lithium disilicate [3]. Several reports have demonstrated the potential for accurate
* Correspondence: [email protected]
Department of Prosthodontics, School of Dentistry, Istanbul Medipol
University, Istanbul, Turkey
and precise restorations using CAD/CAM technology
[4-7].
According to the 8th edition of The Glossary of Prosthodontics Terms, “impression” is defined as “a negative
likeness or copy in reverse of the surface of an object; an
imprint of the teeth and adjacent structures for use in
dentistry” [8]. The accuracy of the impression depends
on the materials themselves [9-13], impression tray types
[14-16], and impression techniques [17-19]. Each step in
the process introduces potential human and/or material
error [20,21].
There is some variability in impressions and the resulting master casts, depending on the technique and material used by the operator [22]. The accuracy of master
casts has been the subject of numerous research projects,
© 2014 Yuzbasioglu et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the
Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public
Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this
article, unless otherwise stated.
Yuzbasioglu et al. BMC Oral Health 2014, 14:10
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and is dependent on numerous items, including the water/
powder ratio, vacuum versus hand mixing [23-25], and the
type of dental stone and its compatibility with impression
materials [26].
Digital impression and scanning systems were introduced in dentistry in the mid 1980s. It was predicted
that most of the dentists in the U.S. and Europe would
be using digital scanners for taking impressions within
the next decade [27]. Digital impressions offer speed,
efficiency, ability of storing captured information indefinitely and transferring digital images between the dental
office and the laboratory [28]. The advantages of the
digital impressions and scanning systems are improving
patient acceptance, reducing the distortion of impression
materials, 3D pre-visualization of tooth preparations,
and potential cost- and time-effectiveness [29].
Several studies on the accuracy of intraoral scanners
and digital impressions have been published, testing
single-unit restorations [30-33], several teeth in a row
[34-36], quadrants [37], and full arch scans [38,39].
A recent report by Lee & Gallucci [40] compared the
operator’s preference of digital versus conventional implant impression techniques. In this in vitro study, inexperienced students made impressions on a customized
model instead of live patients. The overall perception of
the inexperienced students was that they preferred the
digital impression technique. Until now there have been
no clinical studies comparing the digital and conventional impression techniques.
The aim of this clinical trial was to evaluate the effectiveness, clinical outcomes, and patients’ preferences and
attitudes towards the digital impression technique compared to the conventional impression technique. The
first null hypothesis was that there is no difference in
effectiveness and clinical outcomes between the conventional and digital impression techniques. The second
null hypothesis was that there is no difference in patients’ preference and treatment comfort between the
conventional and digital impression techniques.
Methods
Study design & patient selection
A controlled clinical trial was designed. The study population consisted of first year dental and medical students
of the İstanbul Medipol University who had no experience with either conventional or digital impressions. The
subjects were informed in detail about the possible risks
and benefits, and all signed an informed consent form.
The study was performed following the principles outlined in the Declaration of Helsinki on experimentation
involving human subjects. The study protocol was
reviewed and approved by the Ethical Committee of
the Istanbul Medipol University, Istanbul, Turkey,
(No:10840098-74).
Page 2 of 7
Inclusion/exclusion criteria
Twenty-four subjects (12 females, 12 males, aged 21.87
± 2.76 years) who fulfilled the following inclusion criteria
were recruited after an initial examination: no experience with either conventional or digital impressions,
good general health, good oral hygiene, no periodontal
disease, and good mental health. Prerequisites for exclusion in the study were previous impression experience,
fixed or removable prosthetic rehabilitation, orthodontic
treatment and preventive appliances, history of use of
space maintainers in mixed dentition, moderate to excessive dental anxiety.
Clinical scenario
A clinical scenario of an “excessive destruction of a mandibular molar and crown fracture of the lateral incisor,
which would be restored by post-core and all ceramic
crowns” was explained to the subjects during their
orientation to the clinical settings of the study. Subjects
watched an informational video illustrating the restorative steps of the clinical scenario. The impression phase
was excluded from the video.
Conventional impressions
One operator selected the proper tray for both arches of
the subject, and applied the adhesive (Polyether Tray
Adhesive, 3 M ESPE, Dental Products, St. Paul, MN,
U.S.A.). The conventional impressions of mandibular
and maxillary arches were made by polyether impression
material (Impregum Penta Soft Quick Step MB, 3 M
ESPE, Dental Products, St. Paul, MN, U.S.A.) with stock
trays using the monophase impression technique. The
interocclusal relationship was recorded with a polysiloxane bite registration material (Futar D, Kettenbach
GmbH & Co. KG, Eschenburg, Germany). All materials
were used according to the manufacturers’ guidelines
and performed by the same operator (E.Y.).
The effectiveness and clinical outcomes of the conventional impression technique was evaluated by measuring
the total treatment time, including the individual steps
(Figure 1): A) tray selection, B) adhesive application, C)
upper/lower impression, D) bite registration. The treatment time was measured in seconds and recorded for
each step by a second operator (R.T. & H.B.). Immediately after the impressions were made, the attitudes and
perceptions of the subjects towards the conventional impression technique were evaluated using a standardized
questionnaire. The subjects’ perceived source of stress
was also evaluated using the State-Trait Anxiety Scale
immediately after the impression technique.
Digital impressions
A digital impression appointment was scheduled for the
same patients 2–3 weeks following the conventional
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Page 3 of 7
Figure 1 Conventional impression technique. Conventional impression technique. A) Adhesive application, B) Impression tray loading,
C) Upper and lower arches impression, D) Bite registration.
impressions. The digital impressions were performed
with the chairside dental CAD-CAM system (Cerec
OMNICAM, Sirona Dental GmBH, Wals Bei Salzburg,
Austria). The digital impression electronic data constituents of the virtual models for both arches and bite registration were recorded. All digital scanning procedures
were carried out according to the manufacturer’s guidelines and performed by the same operator (EY).
The effectiveness and clinical outcomes of the digital impression technique were evaluated by measuring the total
treatment time, including the individual steps (Figure 2): A)
entering patient information (including name, last name,
date of birth, B) laboratory prescription (including shade of
restoration, material choice of restoration, form of restoration), C) upper/lower scan, and D) bite scan. Treatment
time was measured in seconds and recorded for each step
by a second operator (R.T. & H.B.). Immediately after the
impressions were made, the attitudes and perceptions of
the subjects towards the digital impression technique were
evaluated using a standardized questionnaire. The subjects’
perceived source of stress was also evaluated using the
State-Trait Anxiety Scale immediately after the impression
technique.
The subjects were also asked to answer a 9-item comparative questionnaire including the following research
questions: Which was the preferred impression technique? Which was the recommended impression technique? Which impression technique was more efficient?
Which impression technique would be most comfortable
regarding impression techniques?
Reliability and validity of questionnaires
The questionnaires used in this study were pre-tested,
revised, and retested before use. A pilot questionnaire
was tested on a representative sample of 10 patients.
Test-retest reliability was performed to test the reliability
and internal consistency of the questionnaires. The
Cronbach Alpha reliability coefficient of the scales were
found as 0.921, and 0.982, respectively. The adaptation,
reliability and validity of the Turkish version of the
State-Trait Anxiety Scale were evaluated by Öner and Le
Compte in 1983 [41].
Statistical analysis
Statistical analysis by the Wilcoxon Signed-Rank Test,
with p = 0.05 as the level for statistical significance, was
performed to evaluate the differences in effectiveness
and clinical outcomes between conventional and digital
impression techniques, using the SPSS 15.0 for Windows
statistical software (SPSS Inc., Chicago, IL, USA).
The attitudes and perceptions of the subjects on
both impression techniques were assessed with a selfadministrated questionnaire using a Visual Analog Scale
(VAS) ranging from 0 to 100. The data were analyzed
statistical by the Wilcoxon Signed-Rank Test, with
p = 0.05 as the level for statistical significance, using the
SPSS 15.0 statistical software (SPSS Inc., Chicago, IL,
USA).
The subjects’ preferences for the impression techniques
were assessed with a 9-item comparative questionnaire,
and the distribution of the answers were evaluated by descriptive analysis using the SPSS 15.0 statistical software
(SPSS Inc., Chicago, IL, USA).
Results
The evaluation of the effectiveness and clinical outcomes
for both impression techniques are presented in Table 1.
The mean overall treatment times were statistically
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Page 4 of 7
Figure 2 Digital impression technique. A) Entering patient information, B) Laboratory prescription, C) Upper and lower arches scanning,
D) Bite scanning.
significantly different (p < 0.001), and comparison of the
mean impression times indicated a statistically significant
difference (p < 0.001). The mean tray selection time for the
conventional impression technique and the mean time for
entering patient information for the digital impression
technique were not statistically significant (p > 0.05). The
mean adhesive application time for the conventional impression technique was statistically significantly different
(p < 0.001) from the mean time for entering the laboratory
prescription time for the digital impression technique. The
difference between the mean bite registration time for the
conventional technique and the mean bite scan time for
the digital technique was statistically significant (p < 0.001).
Outcomes of conventional impressions
The mean overall treatment time of the conventional
impression technique was 605.38 ± 23.66 s. The mean
treatment times of the individual steps of the conventional impression technique was as follows: Mean tray
selection time, 18.87 ± 2.42 s; mean adhesive application
time, 27.75 ± 3.12 s. The mean conventional impression
time of the upper and lower jaws was 240.70 ± 16.38 s
and the mean bite registration time was 91.96 ± 10.74 s.
Outcomes of digital impressions
The mean overall treatment time of the digital impression
technique was 248.48 ± 23.48 s. The mean treatment times
Table 1 Scores of clinical efficiency outcomes of impression techniques
Efficiency
Conventional
Digital
Tray selection/Patient information
18,87 ± 2,42
19,08 ± 3,57
>0.05
Adhesive application/Laboratory prescription
27,75 ± 3,12
13,63 ± 1,98
<0.001*
P-value
Upper impression/Upper scan
240,70 ± 16,38
102,14 ± 17,77
<0.001*
Lower impression/Lower scan
226,10 ± 10,89
98,94 ± 10,56
<0.001*
Bite registration/Bite scan
91,96 ± 10,74
14,68 ± 3,82
<0.001*
Total treatment time
605,38 ± 23,66
248,48 ± 23,22
<0.001*
All data are presented as mean ± SD. Measured time is recorded as seconds. *Statistical significance level p-0.05.
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Page 5 of 7
Table 2 Participants’ evaluation scores and level of self concerns about impression techniques
Evaluation (VAS score)
Conventional
Digital
P-value
Overall discomfort of impression
59,00 ± 37,72
90,04 ± 18,37
<0.001*
Overall time of impression
65,10 ± 41,55
90,28 ± 18,36
<0.001*
Smell/Voice
54,90 ± 39,04
86,52 ± 21,16
<0.001*
Taste/Heat
54,20 ± 28,06
88,16 ± 19,76
<0.001*
Queasiness
48,20 ± 44,53
91,80 ± 20,37
<0.001*
Discomfort during mouth was opened
44,40 ± 36,21
88,04 ± 19,86
<0.001*
Discomfort in TMJ
55,90 ± 43,31
88,68 ± 19,83
<0.001*
Breathing difficulty
59,90 ± 37,90
87,32 ± 21,02
<0.001*
Teeth and Periodontal sensivity
47,10 ± 43,21
85,36 ± 23,70
<0.001*
Total evaluation score
507,25 ± 277,34
827,50 ± 171,11
<0.001*
41,33 ± 3,84
43,29 ± 3,89
>0.05
Level of self concern
Score of STATI-TX 1
All data are presented as mean ± SD. Visual Analog Scale (VAS). *Statistical significance level p-0.05.
of the individual steps of the digital impression technique
were as follows: the mean time for entering patient information, 19.08 ± 3.57 s, and the mean time for entering the
laboratory prescription time, 13.63 ± 1.98 s. The mean
digital impression time for the upper and lower jaws was
98.94 ± 10.56 s and the mean bite scan time was 14.68 ±
3.82 s.
Patients’ preferences and self concerns
The evaluation scores and the level of concerns of the
subjects regarding the impression techniques are presented in Table 2. The mean scores of the subjects’
evaluation criteria regarding the two impression techniques were significantly different (p < 0.001). The subjects’ level of self concern were evaluated by scores of
STATI-TX 1. The mean scores were not statistically
significant (p > 0.05). All the subjects preferred the
digital impression technique (p < 0.001), and patients’
preferences regarding the impression techniques, according to the 9-item comparative questionnaire, are
listed in Table 3.
Discussion
In this clinical trial, according to the clinical scenario,
the digital impression technique was more efficient than
the conventional impression technique. Thus, the first
null hypothesis was rejected. The subjects also preferred
the digital impression technique rather than the conventional impression technique because of its comfort.
Thus, the second null hypothesis was also rejected.
The study population was standardized and homogenized by including subjects who had no experience with
conventional or digital impressions in their dental history. To investigate the clinical outcomes of the two impression techniques, homogenizing the study population
is an acceptable clinical research method to optimize objectivity and minimize bias. This approach is important
to avoid reporting the bias of patients who had previous
experience with the dental impression procedure.
In this present study, we focused primarily on the efficiency of the two impression techniques and the preference of the patients under controlled clinical conditions.
Future investigations should include the assessment of
Table 3 Participants’ preferences about impression techniques according to the 9-item questionnaire
Preferences
Conventional Digital
Which impression technique do you prefer in case of one more time for impression procedure?
%0
%100
Which impression technique is more comfortable from point of comparison of two impression procedure?
%0
%100
Which impression technique do you suggest in case of a friends’ need for impression making?
%0
%100
Which impression technique do you prefer from point of time involved with impression procedure?
%0
%100
Which impression technique do you prefer from point of feeling taste/smell or voice/heat during impression procedure?
%0
%100
Which impression technique do you prefer from point of the size of the intraoral scanner/impression tray used in your
mouth during impression procedure?
%0
%100
Which impression technique do you prefer from point of having tooth/gingival sensitivity during impression procedure?
%0
%100
Which impression technique do you prefer from point of having difficulty in breathing during impression procedure?
%0
%100
Which impression technique do you prefer from point of having gagging reflex during impression procedure?
%0
%100
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the accuracy of the impressions produced by experienced versus non-experienced operators, comparison of
using scanning powders versus non-powder scanning,
and comparison of full arch and partial impressions.
There are some limitations of this study. The study
was designed as a comparative-controlled clinical trial,
and the sequence of the evaluation of the two impression techniques was chosen for psychological reasons.
There is a 2–3-week interval between the two evaluation
appointments. This time period was deemed sufficient
to erase from memory an event or a process. The evaluation process focuses on the outcomes of the impression
techniques by means of total treatment time in seconds,
and the study does not analyze any differences in precision of the two impression techniques.
Another limitation of the study was that only one operator performed the impression techniques to avoid the
possible inter-operator error, such as the prolonged processing time taken by an inexperienced operator. The
main purpose of the study was to focus on the patients’
perceptions and comfort in using different impression
techniques. Evaluation by a second operator was not
preferred because of main purpose of the study. Further
investigations are planned to evaluate the perceptions of
patients treated by different dental specialties and operator experience to the digital impression technique.
The last limitation of this study is that it ignored the
time factors involved in the conventional impression
technique, such as pouring and mounting the cast, trimming the dies, painting the die spacer, etc. By eliminating
these steps, time for the traditional workflow would be
reduced significantly. Furthermore, the digital impression technique and digital workflow are designed as the
“digital working model” directly from the intraoral scan,
without any additional factors. By virtually eliminating
the intermediate processes, error accumulation in treatment and in the manufacturing cycle is no longer an
issue.
The results of this study have revealed clinical evidence that the digital impression technique can be applied successfully for the impressions of restorative
procedures based on clinical outcomes and the patients’
preferences. However, this study was performed in a
clinical scenario that excluded the effect of actual treatment conditions, perceived dental anxiety and stress associated with treatment. This is an additional limitation
of this study.
The major advantage of digital impressions is reducing
the chair time. The mean total treatment time (p < 0.001)
and the subjects’ evaluation scores (p < 0.001) regarding
the impression techniques were significantly different
(Tables 1 and 2). Improving the level of the patients’
comfort and treatment acceptance (p < 0.001) were other
advantages of the digital impression techniques (Tables 1
Page 6 of 7
and 2). Digital impressions tend to reduce repeat visits
and retreatment, while increasing treatment effectiveness
[42]. Patients will benefit from more comfort and a pleasant experience in the dentist’s chair.
The results of study indicate that the efficiency outcomes of the digital impression technique were higher
than that of the conventional impression technique, with
respect to treatment time taken up and the perceptions
of the subjects. The effectiveness and clinical outcomes
of both impression techniques (Table 1) were evaluated
by recording the treatment time of each step in seconds,
and were significantly different from each other (p < 0.001).
The scores of the evaluation criteria regarding the two
impression techniques (Table 2) that affect the subjects’
perception differed from one another in a statistically
significant manner (p < 0.001).
The differences in the level of treatment comfort evaluated by the subjects, including breathing difficulty,
queasiness, discomfort in the TMJ, and discomfort while
the mouth was kept open were statistically significant
(p < 0.001). Thus, the digital impression technique is
more patient-friendly than the conventional impression
technique. The results of this study present the major
reasons why the subjects preferred the digital impression
technique instead of the conventional impression technique (Table 3).
Conclusions
Within the limitations of this study, the following conclusions can be drawn:
1. The digital impression technique was more efficient
than the conventional impression technique. The
overall treatment time for the conventional
impression technique was longer than that for the
digital impression technique. Thus, the first null
hypothesis was rejected.
2. When compared with the conventional impression
technique, the digital impression technique was
accepted as the preferred and effective technique,
according to the subjects’ perception. Thus, the
second null hypothesis was rejected.
3. The treatment comfort of the digital impression
technique was higher than that of the conventional
impression technique when it was performed by an
experienced operator.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
EY is the designed and carried out the clinical study, collected the data for
analysis , performed the statistical analysis and drafted the manuscript. HK
participated in the design of the study and interpretation of data. RT and HB
were collected the data for analysis. All authors read and approved the final
manuscript.
Registered Dental Hygienist
05/01/2014
Volume 34, Issue 5
How not to overwork your hands
Use a little leverage during periodontal instrumentation
By Cynthia Biron Leiseca, RDH, EMT, MA
Want to reduce the workload on your hands during instrumentation? This article reviews current basic techniques
and presents new techniques that provide the best leverage and require the least effort and workload on your
hands. Some very simple changes to your instrumentation techniques could make major improvements in how
your hands feel at the end of a working day.
As dental hygienists, we have repeatedly heard that incorrect patient-operator positioning while performing
periodontal instrumentation often leads to cumulative trauma disorders (CTDs). To compensate for the lack of
control from incorrect positioning, clinicians not only strain their necks, backs, shoulders, and arms, they also
1
overwork the hands during instrumentation. Even the greatest hand skills are compromised when the clinician
has to compensate for incorrect patient-operator positioning.
(Review "patient-operator positioning" in the Nield-Gehrig textbook, "Periodontal Instrumentation and Advanced
Root Instrumentation," and self-assess your positioning to make corrections before adding new techniques to
your instrumentation methods.)
-----------------------------------------------------------------------------See related articles
 A periodontist's protocols to avoid dental implant complications: Part 2 -- establishing an implant
maintenance protocol
 Creating the Ultimate Patient Experience Through Technology
 Treating implant gingivitis
-----------------------------------------------------------------------------Many dental hygienists have taken great measures to prevent injury. They purchase loupes to improve
positioning, new operator stools, perfectly fitted gloves, new instruments, and they even increase their use of
1
ultrasonic instrumentation. Yet, they still experience pain and may be diagnosed with CTDs such as carpal tunnel
2,3,4
syndrome, ulnar nerve entrapment, de Quervain's disease, tenosynovitis, tendinitis, and others.
Here is a link to a slideshow of CTDs and physical injuries in dental health-care providers:
http://www.slideshare.net/jhpdc/ergonomics-for-dental-hygienists-1178564.
The loupes help with positioning, but they can reduce your tactile sense in subgingival instrumentation.5,6 Tactile
sensitivity makes you more astute at determining the need for additional instrumentation strokes. Clinicians who
lack fine tactile sense end up making excessive strokes, increasing the workload on the hands. During
subgingival instrumentation, clinicians need to focus less on seeing and more on feeling the roots. In their mind's
26
eye, they need to visualize the anatomy of the roots of the teeth as they perform the debridement.
Ultrasonic instrumentation helps remove tenacious calculus and biofilm, but it presents its own set of problems:
hand vibration injuries, hearing impairment, aerosol production, and the fact that it cannot and should not be used
on every patient.7,8,9,10 Evidence shows that the best treatment outcome for periodontal patients comes from a
combination of hand and ultrasonic instrumentation.11,12 It is also easier on the hands of the clinician to
13, 25,26
alternate their instrumentation methods by using a combination of hand and ultrasonic techniques.
Predisposing factors to hand injuries
The first place to look when assessing hand or instrumentation problems is at the hands themselves. Physical
conditions can be a predisposing factor to hand pain and injury, especially when the hands are placed under the
demands of performing periodontal instrumentation.
Joint hypermobility -- The most overlooked predisposing condition is benign joint hypermobility syndrome
(BJHS), which may occur in one or more joints of the hands and is a predisposing factor to carpal tunnel
syndrome.14,15,16 When there is hypermobility of the joints, the muscles of the hand and arm will be
overworked to compensate for the laxity of the joints. With BJHS, it is difficult to apply lateral pressure during the
16
working stroke and then to control the stroke and relax the hand between working strokes.
Fig. 1 Benign hypermobility joint syndrome
Clinicians who do not self-assess their hands might not even know they have BJHS as it is not a pronounced
disfigurement. It can be seen when you press the fingertips against a tabletop and notice the fingers are not
straight, as under pressure, one or more fingers are bent at the knuckles. BJHS may be the reason why they
struggled when learning the techniques and have pain during and after performing periodontal instrumentation
(see Figure 1).
A physician should evaluate a dental clinician who notices joint weakness or hypermobility. The physician may
refer the hygienist to an orthopedic hand specialist. Physical or occupational therapy may be prescribed, as well
16
as joint stabilizing devices that can be worn under surgical gloves.
2
Osteoarthritis or rheumatoid arthritis -- Various types of arthritis can occur, and the condition may require the
hygienist to reduce work hours or leave dental hygiene altogether. An orthopedic hand specialist and/or a
17,18,19
rheumatologist can diagnose the type and severity of arthritis and will recommend treatment and exercises.
Instrumentation techniques that reduce workload on the hands can make a difference in whether the dental
hygienist with arthritis can continue in clinical practice.
Hand weakness -- Hand weakness is determined most accurately through testing by an orthopedic hand
specialist who use devices such as dynamometers to test hand strength.20 Hand weakness is more common to
female clinicians with small hands, but not to male clinicians with small hands.21 Although anyone could have
weak hands, women with small hands are more likely to have weak hands that may be contributing to problems
3
they have with pain associated with periodontal instrumentation. Hand strengthening is beneficial for all clinicians
22, 23
but mandatory for those with weak hands.
Fingernail length -- Research shows that long fingernails reduce pinch force and hand strength in performing
psychomotor tasks. "Long fingernails limit flexion of the finger joints, particularly the metacarpophalangeal joints.
Lack of finger flexion will limit excursion of long flexors and extensors in patients. It is recommended that patients
24
cut their fingernails to a length of 0.5 cm to achieve optimal functional outcomes."
Leverage is key
Leverage is the key to lightening the workload on the hands, and leverage is dependent on proper equipment
and specific instrumentation techniques. Using leverage instead of brute strength and force will prevent
25
overworking the hands. Leverage is maximized with appropriate techniques.
Proper armamentarium includes an array of periodontal instruments that have large handles (size 10). The
instruments must be very sharp to be efficient in latching on to deposits, and this in itself prevents overworking
the hands. The hygienist must have a supportive operator stool and a patient chair that goes low enough to allow
the clinician to work with the forearms parallel to the floor. A clinician who has to reach up to work on the patient
will lose leverage and the ability to control fine hand function in instrumentation.1
Loss of leverage causes:





25,26
Unnecessary tightening of the hands (excessive pinch force)
Excessive lateral pressure
Pulling instead of lifting deposits off the teeth
Unnecessary number of strokes for deposit removal
Fatigue, pain, injury
Avoid using individual fingers or the thumb to perform instrumentation strokes. Instead use your whole hand as a
1
unit and your arm as a continuum. While reviewing a proper grasp may seem too fundamental to the advanced
clinician, it is most often the first aspect of instrumentation to be found in error during an observation of
26
instrumentation of experienced clinicians.
27,28
Thumb pulling during the working stroke results in injury due to overuse of the thumb.
It also causes other
25,26
instrumentation errors such as lack of toe third adaptation of the working end of the instrument to the tooth.
At Boot Camps for Dental Hygiene Educators,26 a simulation lab is used for teaching instrumentation to students
who are from area dental hygiene programs. Educators who are attendees in the "boot camp" take part in
educator evaluation activities to calibrate on evaluating student clinical performance of periodontal
instrumentation. During the evaluation activities, attendees observed students who were activating the
instrumentation working stroke by using a thumb pulling motion. Students using a thumb pulling activation tended
4
to lift the toe third off the tooth, which resulted in their using some of the middle third of the blade during the
working stroke. Not using the toe third of the blade was less effective and required the students to apply
25, 26
additional lateral pressure to remove the synthetic calculus deposits from the teeth of typodonts.
To remediate "thumb pulling activation," students were reminded to use the whole hand as a unit without
independent digital effort. They were given a technique reminder to perform a "roll-check" to make sure the toe
third was locked onto the tooth just prior to initiating the working stroke. Roll-check means that, after the
exploratory stroke and placement of the instrument blade under the deposit, roll the instrument handle/toe toward
26
the tooth to make sure the toe third is on the tooth before you activate the working stroke.
Many experienced clinicians who attended other instrumentation Boot Camps for Dental Hygiene Clinicians
(noneducators) were not completely on the toe third of the blade during their working strokes. They too,
overworked their hands by compensating with additional lateral pressure. So many clinician attendees were
looking for sophisticated techniques to overcome their struggles. The answer was something as simple as not
25,26
really using the toe third of the blade during the working stroke!
Protect your wrist
The old expression "wrist rock" is one that has left our current teaching vocabulary. Bending and flexing the wrist
for each and every stroke often causes injury. The wrist must remain in a neutral position as the hand and arm
1,26,28,29,30
move as a continuum during instrumentation.
During instrumentation, the whole hand and arm move
1
just as they do when one is turning a door knob.
While extraoral fulcrums are most effective for access to maxillary third molars, they are least effective for
leverage and reduced workload on the hand everywhere else in the mouth. This has been clearly demonstrated
in a study conducted at the School of Dentistry, University of California at San Francisco by Dr. Hui Dong et al. In
the study, muscle activity and thumb pinch force were measured by electromyography and pressure sensor to
compare extraoral fulcrums, intraoral single finger rest, and intraoral two-finger rests. Both intraoral fulcrums
(finger rests) significantly reduce muscle activity and thumb pinch in comparison to the extraoral fulcrum that had
31
no finger rests.
To lift deposits from a root surface, the fulcrum (finger rest) placement should be in a more apical position to help
with the leverage of lifting the deposit off the tooth. A more coronal fulcrum (finger rest) placement tends to make
clinicians pull to remove deposits, while a more apical fulcrum placement facilitates leverage for lifting deposits
off the teeth as opposed to trying to pull deposits off the teeth.
Whenever possible, assist with the index finger or thumb of the nondominant hand by pressing against the shank
of the instrument to control the instrument tip. A lifting working stroke will place the least effort and workload on
25,26,32
the hands.
Whenever the index finger or thumb of the nondominant hand can be used to stabilize the shank
of the instrument, there is increased leverage and additional precision for control of the toe third on the tooth (see
Figure 2).
Having the most deft hand skills in periodontal instrumentation cannot spare the overworked dental hygienist.
Too many patients per day and per week with not enough rest periods between patients will overwork the hands.
Even the rest periods between working strokes are important. At the end of the working stroke, the hand should
be relaxed, evidenced by a grasp with soft "C" of the thumb and index finger. The soft "C" grasp remains during
the exploratory stroke and only changes in shape for the working stroke (after the "roll check" at the "lock on toe
1,26
third" step)
(see Figure 3).
When you are working on patients it is difficult to be modifying your instrumentation technique. Work on only one
change per week. Otherwise you will slow yourself down so much you will get behind schedule and become
overly stressed.
Have someone videotape you often to evaluate your progress in reducing your workload to your hands during
instrumentation. You can be your own best teacher. Team up with other hygienists for peer reviews. Be open to
feedback so that you can work smarter and be free of hand pain and fatigue.
There is no doubt you are a dedicated hygienist, or you would not be reading this article and open to new ideas
that could help you last in our profession. Your patients must be pleased with your dedication and excellent care.
The techniques described in this article are to help you prevent injury to yourself while being just as effective as
you always have been at giving quality care to your patients.
5
Self-assessment of hand pain
To determine what is causing your hand pain, start by assessing your hands and joints for arthritis and/or joint
mobility. See your physician if you suspect you have physical hand problems.
Also, have someone videotape you (even using a cell phone will do) while you are performing instrumentation.
Look at the video and run through the following checklist as you assess your performance:
 Proper patient-operator positioning.
 "Pen grasp" with all fingers together so hand can function as a unit.
 Watch to see if you have a soft "C" grasp during the exploratory stroke and working "C" grasp only
during the working stroke.
 Whole hand and arm as a unit during activation of working stroke. No thumb or index finger pulling.
 Fulcrum (finger rests) in more apical placement whenever possible to get the most leverage to lift rather
than pull off subgingival deposits.
 Relaxed hand during exploratory stroke evidenced by soft "C" thumb and index finger.
Cynthia Biron Leiseca, RDH, EMT, MA, is president of DH Methods of Education, Inc. She is the leader of Boot
Camps for Dental Hygiene Educators (www.DHmethEd.com)
6
Earn
1 CE credit
This course was
written for dentists,
dental hygienists,
and assistants.
Current Fluoride Modalities
for Reduction of Dental Caries
A Peer-Reviewed Publication
Written by Heidi Emmerling Muñoz, RDH, PhD, FAADH and Ellen Standley, RDH, BS, MA
Abstract
The dental profession has long
regarded fluoride as a primary element in
the prevention of dental caries. Topical and
systemic fluorides are regularly incorporated within the community, dental office,
and home avenues. Despite the fact there
are other preventive modalities, fluoride
remains a well-established, evidencebased therapeutic intervention. This article
will review the early history; mechanism
of action; delivery methods for fluoride in
private practice, home, and community;
and the clinician’s role in optimizing best
practices and safe use of fluoride.
Educational Objectives
At the completion of this article, the
health care provider shall be able to:
1. Discuss the early studies in the
United States on fluoride and its
relationship to caries.
2. Explain the mechanisms of the
preventive actions of fluoride.
3. Describe the basic delivery
modalities of systemic and topical fluorides including pertinent
information related to their use.
4. Discuss the clinician’s role in
optimizing best practices and
safe use of fluorides.
Author Profiles
Heidi Emmerling Muñoz, RDH, PhD, FAADH is a professor of English at Cosumnes River
College. Prior to her current role, Dr. Muñoz served as interim director and professor of dental
hygiene at Sacramento City College and was a CODA site consultant. Additionally, she is
owner of Writing Cures (www.writingcures.com), a writing and editing service, co-author of
The Purple Guide: Paper Persona, and creator of the Career Development Center for Friends of
Hu-Friedy. She is a frequent contributor to RDH Magazine and has written articles and columns
for a variety of publications. Dr. Muñoz can be reached at [email protected]
Ellen Standley, RDH, BS, MA, is a recently retired professor of dental hygiene at
Sacramento City College where she taught for over 30 years. She is a member of the American
Dental Hygienists’ Association, the California Dental Hygiene Educators’ Association and the
American Academy of Dental Hygiene. Ms. Standley is a past president of the California Dental
Hygienists’ Association and currently serves on the Journal Advisory Board of the Journal of
the California Dental Hygienists’ Association. She can be reached at [email protected]
Author Disclosure
Heidi Emmerling Muñoz and Ellen Standley have no commercial ties with the sponsors or the
providers of the unrestricted educational grant for this course.
Go Green, Go Online to take your course
Publication date: Nov. 2012
Expiration date: Oct. 2015
Supplement to PennWell Publications
PennWelldesignatesthisactivityfor1ContinuingEducationalCredit.
DentalBoardofCalifornia:Provider4527,courseregistrationnumber01-4527-13004
“ThiscoursemeetstheDentalBoardofCalifornia’srequirementsfor1unitofcontinuingeducation.”
ThePennWellCorporationisdesignatedasanApprovedPACEProgramProviderbythe
AcademyofGeneralDentistry.Theformalcontinuingdentaleducationprogramsofthis
programproviderareacceptedbytheAGDforFellowship,Mastershipandmembership
maintenancecredit.Approvaldoesnotimplyacceptancebyastateorprovincialboardof
dentistryorAGDendorsement.Thecurrenttermofapprovalextendsfrom(11/1/2011)to
(10/31/2015) Provider ID# 320452.
This educational activity was developed by PennWell’s Dental Group with no commercial support.
This course was written for dentists, dental hygienists and assistants, from novice to skilled.
Educational Methods: This course is a self-instructional journal and web activity.
Provider Disclosure: PennWell does not have a leadership position or a commercial interest in any products or
services discussed or shared in this educational activity nor with the commercial supporter. No manufacturer or
third party has had any input into the development of course content.
Requirements for Successful Completion: To obtain 1 CE credit for this educational activity you must pay the
required fee, review the material, complete the course evaluation and obtain a score of at least 70%.
CE Planner Disclosure: Heather Hodges, CE Coordinator, does not have a leadership or commercial interest with
products or services discussed in this educational activity. Heather can be reached at [email protected].
Educational Disclaimer: Completing a single continuing education course does not provide enough information
to result in the participant being an expert in the field related to the course topic. It is a combination of many
educational courses and clinical experience that allows the participant to develop skills and expertise.
Registration: The cost of this CE course is $20.00 for 1 CE credit.
Cancellation/Refund Policy: Any participant who is not 100% satisfied with this course can request a full
refund by contacting PennWell in writing.
Educational Objectives:
At the completion of this article, the health care provider shall be
able to:
1. Discuss the early studies in the United States on fluoride and
its relationship to caries.
2. Explain the mechanisms of the preventive actions of fluoride.
3. Describe the basic delivery modalities of systemic and topical
fluorides including pertinent information related to their use.
4. Discuss the clinician’s role in optimizing best practices and
safe use of fluorides.
Abstract
The dental profession has long regarded fluoride as a primary
element in the prevention of dental caries. Topical and systemic
fluorides are regularly incorporated within the community, dental
office, and home avenues. Despite the fact there are other preventive modalities, fluoride remains a well-established, evidencebased therapeutic intervention. This article will review the early
history; mechanism of action; delivery methods for fluoride in private practice, home, and community; and the clinician’s role in
optimizing best practices and safe use of fluoride.
Early History
In 1901, Frederick McKay opened his first dental practice in Colorado where he discovered residents had severe brown stain and mottling that was resistant to decay. McKay researched this aspect of
staining, despite the lack of concern by citizens and lack of interest
by local dentists. Some early research, funded by a $21 grant posited
that excess pork consumption, drinking milk from local cows or
even exposure to radium was the cause of “Colorado Brown Stain.”1
G. V. Black, credited with being one of the nation’s most eminent
dental researchers, came to Colorado to collaborate with McKay in
investigating the prevalence of the Colorado Brown Stain.2
For six years, Black and McKay researched fluoride. First they
showed that mottled enamel occurred during tooth development
in childhood. Next, they found that the teeth that had the stain
had almost no dental decay. Still not knowing the cause, some local
residents suggested researching the water. McKay thought this
had possibilities while Black was not convinced. In 1923, McKay
went to Idaho because he learned that Idaho children also had
brown stain, and discovered the stain did not occur until a new water line was installed from a local spring. McKay still did not know
what was in this spring and he prudently advised they change
water supplies. Several years later, there was no longer mottling
or brown stain. Next, McKay traveled to Bauxite, Arkansas, an
aluminum company town (ALCOA), because there had been reports of brown stain there too. H.V. Churchill, the chief chemist of
ALCOA, hoping to disprove the fear of the dangers of aluminum,
decided to conduct his own test of the water. Churchill discovered
there were high levels of fluoride in the water and subsequently
wrote a letter to McKay in 1931 reporting his findings. McKay
collected water samples which confirmed Churchill’s assertion
that fluoride, not aluminum, was causing the stain.1-3
64 | rdhmag.com
In the 1930s, the United States Public Health Service (USPHS)
started investigating fluoride and its relationship to tooth mottling.
The head of the Dental Hygiene Unit of the National Institute of
Health (NIH) was H. Trendley Dean, who researched the level
of fluoride and the degree of fluorosis. Dean devised the fluorosis
index and was credited with finding that 1 part per million (ppm)
of fluoride in the drinking water was considered the ideal level for
prevention of decay along with minimal fluorosis.3 The Health
and Human Services (HHS) and the Environmental Protection
Agency (EPA) have lowered this level to 0.7 ppm in recent years to
further minimize the risk of fluorosis.4-5
In 1945 the USPHS decided to implement a research project by
adding fluoride to the water supply in Grand Rapids, Michigan.2-3
Results were compared to a control city with no added fluoride.
Thus, Grand Rapids was the first city to have water fluoridation
and served as an early model for epidemiological fluoride research.2
After 11 years, the outcomes revealed that the children of Grand
Rapids born after the water fluoridation had a 60% reduction in
caries.2 This finding was groundbreaking because it proved that
dental decay could be prevented. Thanks to the pioneers McKay,
Black, Churchill, and Dean, with addition of fluoride to the water
and subsequently to dentifrices, rinses, and other dental products,
consumers experience significantly less decay.2-3,5-6
Basics of Fluoride Delivery and Application
Fluoride is available in many different products and modalities of
delivery. Three basic categories of delivery are currently used: 3,6-9
• Systemic: ingested with water supplies or dietary supplementation or food
• Topical: home/self application of dentifrices, rinses, or gels.
Available in prescriptive higher concentrations or over-thecounter lower concentrations.
• Topical: professional application of higher concentration
products in the dental office
Fluoride delivery methods are either systemic (ingestion) or
topical (surfaces of the teeth). It should be noted that systemic fluoride also provides some topical benefits when the ingested fluoride is
circulated in the blood and emerges in very low levels in saliva.3,6-9 In
early days it was thought that fluorides benefitted mainly children;
it is now acknowledged that benefits extend to adults as well as children.3,5-7, 11 The frequent low level concentration of topical delivery is
the main source of the decay reduction benefits.3,6,10
Mechanism of Action
Fluoride reduces decay via three modes:
1. Incorporation of fluoride into the enamel during tooth
development. This results in the formation of fluorhydroxyapatite, which is more resistant to the acid attacks of the decay
process and is a systemic benefit.3,7-9
2. Remineralization/demineralization mechanism. A
major topical benefit. Fluoride enhances remineralization
by combining with the tooth and making the coronal enamel
RDH | February 2013
and root surfaces more resistant to decay. The more resistant
remineralized enamel in turn serves as a deterrent to the
acids, which act to remove minerals from the tooth surface
(demineralization).3,6-10
3. Glycolosis inhibition in caries bacteria. Another topical
benefit, fluoride interferes with the bacterial metabolism of
carbohydrates and reduces acid production, which in turn
reduces decay.3,6-10
Delivery Methods and Benefits
Systemic
Water Fluoridation: Early Grand Rapids studies showed a 60% reduction in decay with water fluoridation. This impressive reduction
made for compelling reasons for water fluoridation throughout the
country. In 2010, 73.9% of the U.S. population on community water
systems received fluoridated water.12 Initially, fluoridated water was
the only source of fluoride. Through the years dentifrice and other
vehicles for fluoride delivery came on the market. The increased
availability of fluoride from a variety of sources produces a dilution of
the benefits from any single source. Therefore, decay reduction from
water fluoridation alone shows a more modest caries reduction of 2040%.3 Additionally, the diffusion, or halo effect, contributes to this
lower number by the fact that residents of nonfluoridated communities may consume food and beverages manufactured in fluoridated
areas; individuals may also work in a fluoridated community but still
reside in a nonfluoridated community, thereby benefitting from water fluoridation while at work.3,7 Despite other sources of prevention,
fluoridation continues to be a safe and effective measure for caries
reduction for all members of the community.3-7 In 1999 the Centers
for Disease Control and Prevention named water fluoridation as one
of the top ten public health measures of the 20th century.3,4,7
Supplements: Besides consuming water, another mechanism
for systemic fluoride is through dietary supplements. Supplements
are prescribed by physicians or dentists for children when the community does not have optimum water fluoridation. Sodium fluoride
supplements are available in drops for infants or tablets/lozenges for
young children.3,6-9,11 In 1994 the prescription age/dose schedule for
fluoride tablets or drops was lowered to minimize the risk of fluorosis
and to account for other available sources such as dentifrices, infant
formulas, and foods made with fluoridated water (diffusion and halo
effect).3,6Recommendations for supplements are more conservative
than in the past. Fluoride supplements are particularly recommended for children who are at high risk for caries and who do not regularly
brush with a fluoride dentifrice.3,11,13-14 The American Dental Association chairside guide for fluoride supplements states that children
who have low caries risk should not receive supplements.15 Furthermore, the practitioner should carefully evaluate all sources of fluoride and conduct a risk assessment before prescribing supplements.
The 2010 Dosage Schedule can be found on the American Dental
Association website at http://ebd.ada.org/contentdocs/6327_
Fluoride_Chairside_Tool.pdf.15 When supplements are indicated,
they should not be initiated until six months of age.7,9,14-16 FurtherRDH | February 2013
more, to maximize the effect, tablets or lozenges should be chewed
or sucked on for at least one to two minutes before being swallowed.6,10,13,16
There has been much discussion on the efficacy of prenatal fluoride. While not contraindicated at this time, the American Academy
of Pediatric Dentistry does not support the use of prenatal fluoride
supplementsbecauseresearchhasindicatedthatthereisnomeasurable benefit compared to postnatal fluoride alone.6,14-15,17-20
Salt and Milk: Regions that do not have a fluoridated water
supply, including places in South America, Latin America, the
Caribbean, and Western Europe, add fluoride to their salt. It is a
convenient alternative and is met with good public acceptance.3,19-20
Fluoride salt is not used in the United States or Canada, since water
fluoridation is fairly common in these regions.19-21 Although not as
popular as fluoride salt, the addition of fluoride to milk has been
used in a few international communities. However, the evidence
supporting fluoride milk to reduce tooth decay is weak.3,19- 20,22
Topical
Topical fluorides are considered the main source of postnatal
benefits and include both home and professional/office applications.3,6,10,14,19,23 Mechanisms of action and caries reduction benefits
for topical fluorides have been the subject of much discussion and
ongoing research.3,6-11,14 Recommendations for the use of topical
fluorides for children and adults vary with respect to frequency
of use (daily, monthly, or yearly), concentration (lower or higher),
and level of risk or susceptibility to caries.6-11,13-14,16,20
Home Topical Applications
Dentifrices: One major source of topical fluoride is dentifrice.
While systemic water fluoridation has impressive benefits, many
authorities attribute the use of fluoride dentifrice as the main vehicle for the global reduction in caries because of its ability to reach a
wider population.20 Between 1960-1964, fluoride dentifrices were
being marketed and recognized as viable therapeutic mechanisms
for reduction of decay.7 Dentifrices can contain either sodium
fluoride (NaF), stannous fluoride (SnF), or sodium monofluorophosphate (MFP).7-9 The amount of fluoride in the dentifrice is
important. Cochrane reviewers found that a minimum of 1,000
ppm of fluoride should be present in dentifrices to be effective in
preventing caries in children.24 For the optimal caries reduction
benefit, over-the-counter (OTC) fluoride dentifrice levels need to
be between 1000-1500 ppm.13,20 Twice-a-day brushing is recommended for over-the-counter fluoride dentifrices.6,11,13,16,19,23 To
maximize the effect, individuals should avoid rinsing after brushing so that more fluoride is retained in the saliva.6, 20, 25
Recommendations for the use of daily over-the-counter fluoride
dentifrices are targeted for quantity of dentifrice according to age
and level of caries risk. Fluoridated dentifrices should be used only
by adults and children over two; young children under two with low
caries risk should use dentifrice without fluoride or a toothbrush
moistened with water.6,11,13,16,19 The American Dental Association
and the American Academy of Pediatric Dentistry recommend consulting with a dentist or physician before using a fluoride dentifrice
rdhmag.com | 65
on children under age two.3,16 Following advice by a dentist, parents
can place a minuscule amount of fluoride dentifrice on a brush for
children under two.3,6,19,23 The amount has been described as: smear,
film, rice, small pea, tiny touch.3,6-7,19,23 For all slightly older children
(aged 3-6 years), the recommendation is to use fluoride dentifrice
with a pea or small pea size.6-7,9,11,13-14,19,23 To minimize the risk of
fluorosis, experts caution that children must not swallow fluoride
dentifrice during or after brushing.6-7,9, 13-14,19,23 Additional safety
precautions for the 3- to 6-year-olds include keeping the dentifrice
container out of the child’s reach and having adult supervision or
assistance while brushing.7,9
Prescription strength fluoride comes in dentifrice and gel
formulas for home use. These products are used by the high caries risk patient 6 years of age and older.16,19 NaF and acidulated
phosphate fluoride (APF) prescription strength gels contain levels
up to 5,000 ppm.7,9,19 An OTC SnF gel that is sometimes recommended by dental professionals is 1,000 ppm.6,19
Mouth rinses: In addition to dentifrices and gels, topical fluorides are marketed in mouth rinses with NaF, SnF, or APF.6-7,8-9,26
Daily OTC sodium-based mouth rinses are 0.02% (NaF), .044%
(APF) or, 0.05% (NaF), which is the most common.6-8,19,26 Another
daily rinse is .63% SnF, which is indicated for dentinal sensitivity
and gingival inflammation as well as caries.8-9,7,9,19 Available by prescription only for weekly use is 0.2% NaF, which is used for highrisk individuals or for public health school rinse programs.7,9,13,20,26
Most sources recognize mouth rinses are not appropriate for
children under age 6 or any individual who has difficulty expectorating.6-9,13,19,26 For optimum efficacy, mouthwashes should be used
for the prescribed amount of time indicated on the bottle, which is
usually one minute.7-9,13
See Table 1 for summary of home-use topical fluoride.
Table 1. Home-use topical fluoride 8,13,19,26
PPM Chemical Concentration
Formula
Dentifrice
1,000- NaF
.22%(1,000
1,500 SnF
ppm)
Na MFP
.4%
1,500- NaF
5,000 SnF
NaF MFP
Gel
Up to NaF
5,000 APF
1,000 SnF
Mouth rinse
230
NaF
0.05%
(most common)
NaF
0.02%
NaF
0.04%
Plus APF
920
NaF
0.2%
200
NaF
0.044%
SnF
0.63%
66 | rdhmag.com
Prescription OTC
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Professional Topical Application: While some dentifrices,
gels, and rinses are patient applied in the home environment, other higher concentration types of fluoride are used in the community and private practice and are applied by dental professionals.
The Centers for Disease Control and Prevention, the American
Dental Association, and the Academy of Nutrition and Dietetics
recognize that professional applications are more beneficial for
moderate to high caries risk individuals.6,14,27-28 Furthermore, the
ADA’s Council on Scientific Affairs acknowledges that children
and adults who are classified as low risk for caries may not receive
additional benefits from professional topical fluoride application.27-28 Clinicians are advised to analyze each case and patient
preferences before making fluoride recommendations for professional applications.27-28
Varnishes: One of the relatively newer modes of delivery is
fluoride varnish. Varnishes are approved by the FDA for desensitization and as a cavity liner.6,19,29 Although the use for caries prevention is off label, it is considered acceptable practice.6,19,20 For
example, practitioners in some European countries and Canada
have been using varnishes for caries prevention since the 1970s
and 1980s.6,19,29-32 Varnishes typically contain NaF 5% with 22,600
ppm or difluorsilane with 1,000 ppm.6,9,13,19 Ease of application,
taste acceptance, ability to set on contact with moisture, and the
small amount required for use gives varnishes some practical clinical advantages.6,29-30,32 It should be noted that adults and children
with a low risk of caries are not likely to receive additional benefits
from varnish applications. However, patients with moderate to
high risk, such as those with a recent history of incipient or early
caries and or other considerations such as xerostomia or dietary
factors, can benefit from varnish applilcations.27-28 Varnishes are
the best and safest recommendation for professional strength
topical fluoride to use for children under age six.9,19 The reason
varnishes are safer for younger children is because the quantity of
fluoride varnish used is significantly less than other professional
strength applications such as gels and rinses, and there is minimal
risk of ingestion since varnishes adhere to the teeth.6,19,32 The
varnish’s adherence to the teeth is an added advantage to fluoride
application because it maximizes and extends delivery.20,30 Varnishes are normally applied two to four times per year, depending
upon level of caries risk.14,19,27-28,31-32 They are used for both adults
and children in private offices and are commonly incorporated in
public health programs for caries in children.20,30-32
Gels and Foams: Professional fluoride applications are
primarily indicated for those with a caries risk who do not have
access to fluoridated water or do not regularly use a fluoride
dentifrice.13,19,23,27-28 Common in-office modalities are gels,
which are 1.23% APF (the most widely used) and 2% NaF
formulations. The APF gel has a concentration of 12,30012,500 ppm. With a pH of 3.5, APF gels are generally contraindicated for composite or porcelain restorations because
APF dissolves some of the filler particles in those materials.6,8
NaF gel has a concentration of 9,000 ppm and, because of its
neutral pH, poses no risk to restorations.6,8 However, some
RDH | February 2013
Table 2. Professional use topical fluoride 6,7, 13,27
Type
PPM
Chemical Formulation
Concentration
Advantages
Disadvantages
Varnish
22,600
1,000
NaF
difluorsilane
5%
Decreased risk of ingestion
Prolonged delivery
Not yet approved for caries prevention
Gels
12,30012,500
APF
1.23%
Greatest fluoride uptake
Pleasant taste
Stable shelf life
Contraindicated for composite and
porcelain restorations
9000
NaF
2%
Neutral pH
20,00025,000
SnF
8%
Solution
of the newer materials are not as sensitive to the effects of
the APF.19 Evidence reveals that the NaF and AFP gels are
similar in efficacy.27 The foam forms of APF and NaF require
a much smaller amount to fill the trays and thereby reduce the
risk of ingestion.6,8-9 The recommended time for professional
fluoride tray applications is four minutes to obtain maximum
benefits.6-9,13,19,27 Patients should be advised not to rinse, eat,
or drink for 30 minutes following high concentration fluoride
applications to maximize effectiveness.6-9,13,19
Another application that is rarely used, with its high concentration of 20,000-25,000 ppm, is an 8% SnF solution. Since it is
SnF, it has a less pleasant taste, and there is a potential problem
for staining as well as gingival sloughing. Instability is another
disadvantage of this formulation.8
At one time, a two-part fluoride rinse consisting of 0.31%
APF and 1.64% SnF was popular. At 1,500-3,000, the ppm was
lower than gels and foams. However, the lack of clinical evidence
no longer warrants its use.9 See Table 2 for a summary of professional topical solutions.
The Clinician’s Role in Optimizing Safe Use of
Fluorides
Dental hygienists should keep informed on the current use of
fluoride modalities, best practices, and safe strategies. Additionally, it is important to inform the patients how to maximize
efficacy and minimize potential risks.
Caries Risk Assessment: Caries risk assessment is
evidence-based and considered the current best practice when
clinicians implement and recommend caries prevention strategies.27-28 Each patient is evaluated with consideration for clinical exam, history of recent caries, nutritional and oral hygiene
practices, and many other factors. Several risk assessment forms
and articles are available and can be downloaded.14-16,27-28
Acute and Chronic Toxicity: Acute fluoride toxicity
results from short-term ingestion of higher concentrations of
fluoride. Symptoms can range from mild nausea to more severe
GI symptoms and, in extremely rare cases, death.7,9 The severity
of symptoms is affected by the amount of fluoride ingested, the
patient’s weight, and the patient’s health status.7,9 Mild nausea
RDH | February 2013
Staining
Unpleasant taste
Gingival sloughing
is the most common form of fluoride toxicity and is experienced
when patients swallow too much topical fluoride. The fluoride
reacts with the stomach acid, forming hydrogen fluoride and
produces symptoms of nausea, cramps, and vomiting, usually
within 30 minutes of swallowing.7,9,19
Chronic fluoride toxicity results from long-term ingestion
of lower concentrations of fluoride, and is most commonly experienced as dental fluorosis.3,6-7,9 Fluorosis ranges from mild
chalky white spots to severe brown mottling.3,6 Fluorosis develops when low doses of fluoride are regularly and inadvertently
ingested during enamel development.3,6 Although fluorosis is
seen when the fluoride concentration in the water is greater than
optimal, some cases of fluorosis result from long-term swallowing of OTC dentifrices, and/or the use of supplements and
fluoridated infant formula in addition to consuming water that
is already optimally fluoridated.3,6,9,13,17,23
Safe Tray Applications: To avoid the potential of acute
toxicity symptoms, common sense dictates that clinicians follow
best practices when administering tray applications of fluoride.
These include:7,9,19
1. Load a minimal amount of product for tray applications. To
minimize the risk of ingestion, load 2 ml per tray for small
children and no more than 5 ml per tray for adults. Have the
patient sit upright.
2. Apply adequate suctioning throughout the procedure.
3. Directly supervise the patient, especially young children,
during the administration of fluoride. Children are at a greater
risk of fluoride toxicity since they do not weigh as much as
adults and also tend to swallow topical fluoride. Thus, careful
supervision of child during fluoride treatments is essential.
4. Instruct the patient to expectorate and not to swallow the
product.
5. Advise the patients who have a tendency to swallow product
that they can ingest milk or an antacid product (calcium carbonate) to bind with the fluoride, reducing the risk of nausea.
Reminders for Patients: It is important that clinicians advise
patients of safety precautions for home use of fluoride products.
Safety messages to convey include: 7,9,13,14,19,33
rdhmag.com | 67
1. All fluoride products, including OTC dentifrices and rinses,
must be stored out of the reach of small children. Further
precautions dictate that prescription fluoride should be stored
in a secure area.
2. Remind patients that the proper amount of dentifrice for a
small child to use is the size of a small pea.
3. No mouth rinses should be used by children under the age of
six or by individuals who have limited ability to expectorate.
4. Mouthrinses and dentifrices should not be swallowed.
Therefore, parental supervision of young children is essential.
5. Before supplements and/or fluoridated infant formula are
used, check the fluoride content of the local water supply. If
the fluoride concentration is at the optimal level, supplements
and fluoride-enriched formula should not be used.
6. When daily supplements are taken, parents should be advised
that if a dose is missed, simply resume the next day with the
normal dose. Do not double dose.
7. Remind parents that if fluoride is ingested and nausea is
experienced, they should take proper measures by having the
child consume milk or an antacid product to bind with the
fluoride. If accidental ingestion of a larger amount of fluoride
product occurs, the National Hotline for Poison Emergencies
is available for 24 hour advice. (1-800-222-1222) 33
Conclusion
Because practitioners and consumers have enjoyed the benefits of
fluoride for a number of years, fluoride is often taken for granted as
one of the most effective tools for caries prevention. Whether in the
water supply or in topical agents such as daily dentifrice, fluoride
continues to be relied on as a preventive measure. Despite its longstanding history and use, clinicians should have basic knowledge of
the products and of the safe use of these products. Communication
to the patient is an important adjunct to maximize the benefits and
minimize the risks. Timely implementation of caries risk assessments and of appropriate strategies for each patient’s level of risk
are essential components of evidence-based practice. From its early
history to the present time, fluoride remains an effective, evidencebased modality for caries prevention throughout the lifespan.
References
1. “Hall of Fame Inductees Frederick S. McKay” Pierre Fauchard
Academy. Web. Accessed 9/2/12 http://www.fauchard.org/awards/
hall_of_fame/frederick_mckay.html.
2. “Story of Water Fluoridation” National Institute of Dental Research,
National Institute of Health. Article. 3/11. Web. Accessed
5/23/12.
http://www.nidcr.nih.gov/oralhealth/topics/fluoride/
thestoryoffluoridation.htm.
3. Fluoridation Facts. American Dental Association. 5th Ed. 2005. Web.
Accessed 9/4/12. http://www.ada.org/sections/newsAndEvents/
pdfs/fluoridation_facts.pdf.
4. Nathe C. “Community Water Fluoridation.” RDH magazine. May
2011. 31(5) Print.
5. “HHS and EPA announce new scientific assessments and actions
on fluoride” Health and Human Services. Press Release, January
7, 2011. Web. Accessed 7/3/12.
http://www.hhs.gov/news/
press/2011pres/01/20110107a.html.
6. Centers for Disease Control and Prevention. “Recommendations for
68 | rdhmag.com
using fluoride to prevent and control dental caries in the United States.”
MMWR Recomm Rep. 2001;50(RR-14):1–42. PMID 11521913. Lay
summary: CDC, Web. 2007-08-09. Web. Accessed 7/2/12. http://
www.cdc.gov/mmwr/preview/mmwrhtml/rr5014a1.htm.
7. Harris N, Garcia-Godoy F, Nathe C. Primary Preventive Dentistry. 7th
Ed. Upper Saddle River: Pearson. 2008.
8. Darby M, Walsh M. Dental Hygiene Theory and Practice. 3rd Ed. St.
Louis: Elsevier. 2010.
9. Wilkins E. Ed. Clinical Practice of the Dental Hygienist. 11th Ed.
Philadelphia: Lippincott Williams & Wilkins. 2013.
10. Featherstone JD. “Prevention and reversal of dental caries: role of
low level fluoride.” Community Dent. Oral Epidemiology, 1999:
27:31-40. Web. Accessed 7/3/12. http://www.ncbi.nlm.nih.gov/
pubmed/10086924.
11. “Using Fluoride to Prevent and Control Tooth Decay” Centers for
Disease Control. Fact Sheet. 1/7/11. Web. Accessed 5/23/12. http://
www.cdc.gov/fluoridation/fact_sheets/fl_caries.htm.
12.
“2010 Water Fluoridation Statistics.” Centers for Disease
Control.7/27/12. Web. Accessed 8/23/12. http://www.cdc.gov/flu
oridation/2010waterfluoridationstatistics.html.
13. “Other Fluoride Products.” Centers for Disease Control. Fact Sheet.
1/6/11. Web Accessed 8/23/12. http://www.cdc.gov/fluoridation/
other.htm.
14. Palmer CA, Gilbert JA. “Position of the Academy of Nutrition and
Dietetics: The Impact of Fluoride on Health.” Journal of the Academy
of Nutrition and Dietetics. 2012: 112: 1443-1453. Web. Accessed
9/3/12. http://www.eatright.org/About/Content.aspx?id=8364.
15.
“Dietary
Fluoride
Supplements:
Evidence-based
Clinical
Recommendations.” ADA chairside guide. Nd. Web. Accessed
7/3/12. http://ebd.ada.org/contentdocs/6327_Fluoride_Chairside_
Tool.pdf.
16. “Guidelines for Fluoride Therapy.” American Academy of Pediatric
Dentistry. Oral Health Policy. Revised 2012. Web. Accessed
7/10/12.
http://www.aapd.org/media/Policies_Guidelines/G_
FluorideTherapy.pdf.
17. “Findings Suggest Fluoride Supplements During Pregnancy Provide
Little or No Benefit.” National Institute of Dental and Craniofacial
Research. Science News in Brief. Web. 11/28/05. Accessed 5/23/12.
http://www.nidcr.nih.gov/Research/ResearchResults/ScienceBriefs/
Archive/SIB2005/November/SIB11282005.htm.
18.Sa Roriz Fonteleles C, Zero DT, Moss ME, Fu J. “Fluoride
Concentrations in Enamel and Dentin of Primary Teeth After Pre- and
Postnatal Fluoride Exposure.” Caries Research. 2005 Nov-Dec; 39 (6):
505-508. Web. Accessed 5/23/12. http://www.ncbi.nlm.nih.gov/
pubmed/16251796.
19.Adair S. “Evidence-based Use of Fluoride in Contemporary
Pediatric Dental Practice.” Pediatric Dentistry. 2006: 28: 133-142
Web. Accessed 7/10/12. http://health.mo.gov/blogs/wp-content/
uploads/2011/09/Adair-2006.pdf.
20. Burt B, Eklund S. Dentistry, Dental Practice, and the Community. St
Louis: Elsevier. 2005.
21. Dais Joyce.“Fluoride Facts.”Dimensions of Dental Hygiene. July 2007: 2830. Web. Accessed 5/23/12. http://www.dimensionsofdentalhygiene.
com/ddhnoright.aspx?id=1173&term=2007%20%20Dais%20%20
Fluoride.
22. Yeung A, Hitchings JL, Macfarlane TV, Threlfall A, Tickle M, Flenny
A-M, “Fluoridated milk for preventing dental caries.” Cochrane
Summaries. 10/8/2008. Web. Accessed 5/23/12. http://summaries.
cochrane.org/CD003876/fluoridated-milk-for-preventing-dentalcaries.
23. “Use of Fluorides in Caries Prevention.” Canadian Dental Association.
Position Paper. March 2012. Web. Accessed 8/2/12. http://www.
fluoridation.com/CalgaryFluoride/CDA_Fluoride-Guidelines.pdf.
24. Walsh T, Worthington HV, Glenny A-M, Appelbe P, Marinho VCC,
Shi X. “Comparison between different concentrations of fluoride
toothpaste for preventing tooth decay in children and adolescents.”
Cochrane Summaries. 2/17/2010. Web. Accessed 9/11/12. http://
summaries.cochrane.org/CD007868/comparison-between-differentconcentrations-of-fluoride-toothpaste-for-preventing-tooth-decay-inchildren-and-adolescents.
25.Duckworth RM, Maguire A, Omid N, Steen IN, McCracken GI,
RDH | February 2013
INSTRUCTIONS



Read through the article and answer the multiple choice questions provided at the back of the article.
Please note that some questions may have more than one answer; in the case of the latter please “tick” every correct answer.
When done only fax through your answer sheet to the fax number given on the answer sheet.
QUESTIONNAIRE
B2 (14)
CYTOTOXICITY OF QMix™ ENDODONTIC IRRIGATING SOLUTION ON HUMAN BONE MARROW MESENCHYMAL
STEM CELLS
Question 1: Which of the following are characteristics of an ideal
root irrigant solution?
A It must be nontoxic
B It must have a broad antimicrobial spectrum
C It must have the ability to dissolve pulp tissue
D It must be able to inactivate endotoxins
E It must prevent the formation of a smear layer or
dissolve it
Question 2: Is it TRUE or FALSE that there is currently a new irrigant
solution that can achieve all the ideal goals?
A TRUE
B FALSE
Question 3: The use of which of the following irrigant solutions has
been advocated by many researchers to produce optimal root canal
irrigation results?
A EDTA and NaOCI combined
B EDTA on its own
C CHX and NaOCI combined
D EDTA, CHX and NaOCI combined
E NaOCI on its own
Question 4: QMix™ is a 2-in-1 solution containing which of the
following agents?
A 15% EDTA and 3% CHX
B 5% NaOCI and 17% EDTA
C 2% CHX and 17% EDTA
D 17% CHX and 2% EDTA
Question 5: Which of the following statements are TRUE with
regard to the observations of the in vitro study?
A Both the QMix™ and NaOCI solutions are toxic to human
bone marrow MSC’s and cause cellular damage
B The NaOCI solution, but not the QMix™ solution, is toxic
to human bone marrow MSC’s and cause cellular
damage
C Both the QMix™ and NaOCI solutions are toxic to human
bone marrow MSC’s but do not cause cellular damage
D The QMix™ solution, but not the NaOCI solution, is toxic
to human bone marrow MSC’s and cause cellular
damage
Question 6: Is it TRUE or FALSE that Qmix™ was found to be nontoxic and cannot induce an inflammatory response?
A TRUE
B FALSE
Question 7: Which of the following statements are TRUE with
regard to cell viability after exposure to irrigant agents?
A The toxic effect of an agent gradually increases with time
B Cell viability increased significantly when the cells were
exposed to NaOCI for all time periods examined
C Cell viability decreased significantly after being exposed
to the QMix™ solution for 2 or 4 hours
D CHX is a toxic agent that binds to the cell’s plasma
membrane and increases its permeability
1
Question 8: Which one of the following types of cell death does not
induce an inflammatory response, and is characterized by cell
shrinkage and the nuclear chromatin condensation followed by
nuclear fragmentation?
A Autophagy
B Apoptosis
C Necrosis
D Mitotic catastrophe
Question 9: Which of the following markers are necessary to
substantiate this mode of cell death speculated with QMix™?
A Regulators
B Cleaved substrates
C Inhibitors
D Detection of caspases
E All the above
Question 10: Is it TRUE that in vitro cytotoxicity investigations
reported that CHX had a higher toxicity in cell cultures than NaOCI,
but that in vivo studies suggest that CHX or QMix™ is less aggressive
than NaOCI?
A YES
B NO
COMPARISON OF DIGITAL AND CONVENTIONAL IMPRESSION TECHNIQUES: EVALUATION OF PATIENTS’
PERCEPTION, TREATMENT COMFORT, EFFECTIVENESS AND CLINICAL OUTCOMES
Question 11: Which of the following are advantages of digital
impressions and scanning systems?
A 3D pre-visualization of tooth preparations
B Potential cost- and time-effectiveness
C Reducing the distortion of impression materials
D Improving patient acceptance
E All of the above
Question 12: With regard to the outcome of this study, which of
the following are TRUE?
A The conventional impression technique was more
efficient than the digital impression technique
B Trial subjects preferred the conventional impression
technique
C The digital impression technique was more efficient
than the conventional impression technique
D Trial subjects preferred the digital impression technique
Question 13: Which one of the following was the major advantage
of digital impressions?
A Improving the level of patients’ comfort and treatment
acceptance
B Reducing the chair time
C Reducing repeat visits and treatment
D Increasing treatment effectiveness
Question 14: Which one of the following is the more patientfriendly technique?
A The digital impression technique
B The conventional impression technique
Question 15: The accuracy of the conventional impression
technique depends on which of the following?
A The materials themselves
B Impression tray types
C Impression techniques
D All of the above
2
HOW NOT TO OVERWORK YOUR HANDS
Question 16: Can incorrect patient-operator positioning while
performing periodontal instrumentation lead to cumulative trauma
disorder?
A YES
B NO
Question 17: Which of the following statements regarding
measures to prevent injury are TRUE?
A The loupes help with positioning and they increase your
tactile sense in subgingival instrumentation strokes
B During subgingival instrumentation, clinicians need to
focus less on seeing and more on feeling the roots
C Ultrasonic instrumentation helps to remove tenacious
calculus and biofilm
D Ultrasonic instrumentation should and can be used on
every patient
E According to evidence the best treatment outcome for
periodontal patients comes from a combination of handand ultrasonic instrumentation
Question 18: Which of the following is FALSE with regard to BJHS?
A It is the most overlooked predisposing condition
B It may occur in one or more joints of the hands and is a
predisposing factor to carpal tunnel syndrome
C With BJHS, it is difficult to apply lateral pressure during
the working stroke and then to control the stroke and
relax the hand between working strokes
D Clinicians always know when they have BJHS, even if
they do not self-assess their hands
E BJHS may be the reason why clinicians have pain during
and after performing periodontal instrumentation
Question 19: Who is most likely to have hand weakness?
A Female clinicians with small hands
B Male clinicians with small hands
C Female clinicians with large hands
D Male clinicians with large hands
Question 20: Is it TRUE or FALSE that leverage is key to lightening
the workload on the hands?
A TRUE
B FALSE
Question 21: Since leverage is dependent on proper equipment
and specific instrumentation techniques, which of the following are
TRUE?
A The instruments do not have to be sharp to be efficient
in latching on to deposits
B The patient’s chair must go low enough to allow the
clinician to work with the forearms parallel to the floor
C Using individual fingers or the thumb to perform
instrumentation should be avoided
D Thumb pulling during the working stroke does not result
in injury due to overuse of the thumb
E Thumb pulling causes errors, such as lack of toe third
adaptation of the working end of the instrument to the
tooth
Question 22: To lift deposits from a root surface, the fulcrum
placement should be in which position?
A The apical position
B The coronal position
Question 23: Which of the following are CTDs that can be caused
by overworking the hands?
A
B
C
D
E
Carpal tunnel syndrome
Ulnar nerve entrapment
Tendinitis
Quervain’s disease
Tenosynovitis
3
CURRENT FLUORIDE MODALITIES FOR REDUCTION OF DENTAL CARIES
Question 24: Who were the pioneers that collaborated to
investigate the prevalence of the Colorado Brown Stain?
A Churchill
B Dean
C McKay
D Black
Question 25: The Health and Human Services and the
Environmental Protection Agency have lowered the fluoride level
to which of the following to further minimize the risk of fluorosis?
A 0.6 ppm
B 0.7 ppm
C 0.8 ppm
D 0.9 ppm
E 1 ppm
Question 26: Is it TRUE or FALSE that fluoride benefits both
children and adults ?
A TRUE
B FALSE
Question 29: Fluoride supplements are recommended for whom
of the following?
A Children who have low caries risk
B Children who do not regularly brush with a fluoride
dentifrice
C Children under the age of 6 months
D Children who are at high risk from caries
Question 30: Which one of the following is attributed by many
authorities as the main vehicle for the global reduction in caries
because of its ability to reach a wider population?
A The use of fluoride dentifrice
B Systemic water fluoridation
C Varnishes
D Mouth rinses
Question 31: For optimal caries reduction benefit, what must the
over-the-counter fluoride dentifrice levels be?
A Below 500 ppm
B Between 500 – 800 ppm
C Between 800 – 1000 ppm
D Never more than 1000 ppm
E Between 1000 – 1500 ppm
Question 27: Which of the following are systemic methods of
fluoride delivery?
A Supplements
B Water fluoridation
C Salt and milk
D All of the above
Question 28: Early Grand Rapids studies showed what percentage
reduction in decay with water fluoridation?
A 20%
B 40%
C 60%
D 80%
Question 32: Are mouth rinses appropriate for children under age
6?
A YES
B NO
Question 33: Which of the following are FALSE with regard to
professional topical application of fluoride?
A The CDCP, ADA and AND recognize that professional
application of fluoride is less beneficial for moderate to
high caries risk individuals
B Clinicians should analyze each case, and patient
preferences before making fluoride recommendations
for professional application
C There is no additional benefit for any group of people
from professional topical fluoride application
D The ADA and Council of Scientific Affairs acknowledge
that children and adults who are classified as low risk for
caries may not receive additional benefits from
professional topical fluoride application
4
Question 34: Which of the following give varnishes some practical
clinical advantages?
A Taste acceptance
B Ease of application
C The small amount required
D Ability to set on contact with moisture
Question 35: Who can benefit from varnish applications?
A Adults with low risk of caries
B Patients with moderate to high risk of caries
C Children with low risk of caries
D Patients with xerostomia or other dietary factors
E Patients with a recent history of incipient or early caries
Question 38: Is it suitable for individuals who have limited ability to
expectorate to use mouth rinses?
A YES
B NO
Question 39: Is it TRUE or FALSE that before supplements and/or
fluoridated infant formula are used, the fluoride content of the
local water supply must be checked and if it is at its optimal level, it
should not be used?
A TRUE
B FALSE
Question 40: Which one of the following is TRUE?
Question 36: Is it TRUE or FALSE that varnishes are the best and
safest recommendation for professional strength topical fluoride to
use for children under age six?
A TRUE
B FALSE
A Fluoride is an effective, evidence-based modality for
caries prevention for children but not adults
B Fluoride remains an effective, evidence-based modality
for caries prevention throughout the lifespan
Question 37: In which of the following cases can dental fluorosis
develop?
A From a once-off ingestion of a low dose of fluoride
B From a once-off ingestion of high concentrations of
fluoride
C When low doses of fluoride are regularly and
inadvertently ingested during enamel development
D From long-term swallowing of OTC dentifrices
E When the fluoride concentration in the water is greater
than optimal
5
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B2 (14)
CYTOTOXICITY OF QMix™ ENDODONTIC IRRIGATING SOLUTION ON HUMAN BONE MARROW MESENCHYMAL STEM CELLS;COMPARISON OF
DIGITAL AND CONVENTIONAL IMPRESSION TECHNIQUES: EVAUATION OF PATIENTS’ PERCEPTION, TREATMENT COMFORT, EFFECTIVENESS AND
CLINICAL OUTCOMES;HOW NOT TO OVERWORK YOUR HANDS;CURRENT FLUORIDE MODALITIES FOR REDUCTION OF DENTAL CARIES
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