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Endodontics
E
ndodontics
Mar 2015
CONTINUOUS WAVE TECHNIQUE: TEMPERATURE CHANGES IN
DIFFERENT PARTS OF THE TOOTH ROOT
Department of Dentistry
Smolensk State Medical University, Russia.
Dr. Nikolaev A.I.
Head
Dr. Ginali A.N.
Dr. Nikolaeva E.A.
Student
Lecturer
Relevance
Up-to-date endodontic treatment is a high-end technological procedure.
Thanks to scientific studies, material and economic base perfection in last
decade the paradigm of endodontic treatment has been changed: the main
conditions of it are three-dimensional cleaning and obturation of a root canal
system.9,19 To provide the successful solution of this task new methods of
root canal filling are invented, existing ones are modified.7,14 Improvement of
technology of warm vertical compaction (condensation) of gutta-percha led
to the invention of the special devices and protocols – thermopluggers and
the “continuous wave” technique.3 Modern thermoplugger – is an electronic
device with a plugger-shaped working end. It can be used for both heating
and compacting gutta-percha in root canal. Commonly in clinical conditions,
apical third of a root canal filled using continuous wave, and the middle
and cervical thirds are filled with melted gutta-percha with the help of a
special injector (extruder). This procedure was named “Hybrid technique” [16,
19]. Currently, varieties of devices from different manufactures for hybrid
obturation are presented at the market (Fig. 1).
The study investigated the dynamics of temperature
changes on the outer surface of the tooth root during
root canal obturation using continuous wave technique.
Established the safety of this procedure for periodontal
tissues, which allows us to recommend it for use on an
everyday dental practice.
KEYWORDS: Endodontic treatment, root canal
obturation, gutta-percha, down-pack plugger, continuous
wave technique.
c)
a)
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b)
d)
Fig. 1. Up-to-dated electronic devices for root canal obturation with
warm gutta-percha using the continuous wave technique:
Mar 2015
a – cordless electric devices for filling root canals with warm guttapercha, equipped with functions of LED working area highlighting,
plugger vibration and intraradicular irrigation solution activation
GuttaEst-V (L) and extruder for filling root canal with warm gutta-percha
GuttaFill (GeoSoft Dent);
b – electric device for hybrid technique of root canal obturation with
methods of vertical condensation and injection of warm gutta-percha
(Dentsply);
c – cordless system of three-dimensional root canal obturation with
warm gutta-percha E&Q Master (Meta Biomed);
d – thermoplugger for heating, cutting and condensation of guttapercha for GuttaEst-V (L) device; taper /size – .045 / ISO 50; color codered.
At the same time, the level of application of new, high efficient root canal
obturation technologies in practical dentistry cannot be considered as
acceptable.
Our survey-questionnaire of 172 dental therapists who also provide endodontic
treatment showed, that more, than one half of questioned (64,5%) use
rotary NiTi instruments (36 dentists use only NiTi instruments, 75 – combine
them with classical manual instruments). Only 21 dental therapists (12,2%
of questioned specialists) use up-to-date methods of root canal obturation
with warm gutta-percha. Overwhelming majority (151 dentist or 88,8%
questioned) fill root canals using cold lateral gutta-percha condensation, that
has a number of disadvantages. The main of them are non-homogenous canal
filling, thick layer of sealer between posts, and a high risk of vertical root
fracture.6,12,16
A range of factors can explain the state of affairs: from the lack of material
and technical support of dental clinics to low level of theoretical and practical
dentist’s training.5,9,13,14 A vagueness of a number of aspects of clinical
usage of vertical gutta-percha compacting plays an important role. Many
dentists consider this method dangerous for periodontal tissues due to high
temperature (200-300°C), used during vertical gutta-percha compacting
using continuous wave.
Despite the fact, that technique of three-dimensional root canal filling
using thermoplastic gutta-percha exists more, than a decade1,18,23 there is
no well-defined opinion about safe limits of temperature increasing inside
the tooth and on the external surface of the root. Only single studies about
influence of high temperatures on tooth and periodontal tissues during filling
process are found in literature. Many of them contradict each other.17,20,21
A. Behnia and N.J.McDonald2 ascertained, that at a temperature of 56°C
alkaline phosphatase inactivation takes place in bone tissues, which leads
to destruction of the last. Authors also showed that heating bone tissues at
a temperature of 50°C during 1 minute or at a temperature of 47°C during
5 minutes leads to bone resorption and replacing of missing structures with
adipose tissues. A.R.Eriksson and T.Albrektsson,4 E.M.Hardie8 assert, that
alteration in bone tissues can be noticed after increasing the temperature
on the external surface of the root up to 44-47°C during 1 minute. At the
same time, D.L.Husseyet et al.10 and M.Lipski11 proved, that short-term
temperature increasing on an external surface of the root by 10 10°C is safe
for surrounding tissues.
Endodontics
E
ndodontics
Because of above-stated, it seems relevant to investigate real temperatures,
arising in tooth, periodontal tissues and in alveolar bone during filling root canal
with warm gutta-percha, taking into account permissible limits of heating and
constructional features of modern endodontic devices and instruments.
The aim of the study
The aim of the study is to look into the temperature changes, taking place in
tooth and periodontal tissues during root canal filling using continuous wave
technique with modern electronic thermoplugger.
Materials and Methods
The study involved 20 intact single-canal premolars, extracted due to
orthodontic prescriptions. Tooth were picked out not later than 15 minutes
after extraction, cleaned and placed into +4°C distilled water for not more,
than 10 days.
After creating endo access, premolar root canals were proceed by a standard
protocol. Canal was navigated using steel K-files #10; glide-path was created
using rotary nickel-titanium instruments “PathFile” (Dentsply). On this stage
tooth canals were shaped till ISO size 19. To shape the canals, rotary NiTi
instruments «ProTaper» (Dentsply) until F2 file size (working end tip diameter
– 25 ISO). Current and finishing irrigation was provided by 3% solution of
sodium hypochlorite («Parcan», Septodont) using passive ultrasonic activation.
As a completion, root canals were irrigated using 10ml of distilled water and
dried with paper points.
The «GuttaEst-V (L)» (GeoSoft Dent) device was used during laboratory
investigation of temperature changes in tooth tissues during canal filling using
continuous wave technique.
After tooth canal preparation, a thermoplugger was fitted. Working end size
was selected to be wedged 5mm before apical foramen (fig. 2,). F2 size guttapercha post was fitted on a working length (fig. 2, b).
a
b
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Endodontics
E
ndodontics
Fig. 2. Preparation of the laboratory’s tooth root canal for filling (sketch):
a – plugger fitting (WL - 5 mm);
b – fitting gutta-percha post till WL.
K-type thermocouples (chromel/alumel) with a sensor size of 0.5mm were
installed in predetermined points of the tooth. They were connected to the
computer using UT323 (UNI-T) thermometer (Fig. 3). For the simplicity of text
perception by dentists without engineering education, the authors consider
rational to replace the term “K-type thermocouple” by the term “thermo
sensor”.
Mar 2015
The fitted gutta-percha post with sealer «AH Plus» (Dentsply) was immersed
into the root canal. The system with tooth and thermo sensor was placed
into a thermostat with warm water (+37°C). After that canal was filled
using continuous wave technique according to the generally accepted rules11
using thermoplugger «GuttaEst-V (L)» (GeoSoft Dent). The temperature was
set to 200°C. The tip of the thermoplugger was placed on the canal opening,
then heating was activated and the instrument was forwarded through guttapercha with one movement on a level 3mm shorter, than determined length
(fig. 5, a). After that heating was switched off and, keeping apical pressure,
instrument tip was forwarded down to determined point (fig. 5, b). Reaching
determined point, apical pressure on a plugger was kept during 10 more
seconds to compensate cooling gutta-percha shrinkage. (fig. 5, c). After that,
plugger was removed with gutta-percha remains (fig. 5, d). Output data from
thermo sensors were captured using special software.
Fig. 3. Elementary diagram of the laboratory investigation.
Two thermo sensors (N1, N2) were installed on an external surface of the
root at a distance of 8 and 5 mm from tooth apex. For the third thermo
sensor, a tiny canal was burred at a distance of 3mm from the apex to record
temperature changes in gutta-percha post. Thermo sensor #4 was installed in
the area of tooth apical foramen (fig. 4).
a)
c)
b)
d)
Fig. 5. Scheme of root canal filling using continuous wave technique
during laboratory investigation:
Fig. 4. Scheme of thermo sensors positions in under study tooth.
a – inputting warm plugger into the root canal;
b – immersing plugger and compacting gutta-percha in the apical
direction with the instrument heater off;
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Mar 2015
c – reaching preset work length of a plugger immersing with a constant
apical pressure on an instrument;
d – excretion of the plugger with gutta-percha remains.
Clinical part of investigation took place on a basis of dental clinic «MAH»
(city Bryansk). Efficiency, ergonomic, specifications and clinically important
characteristics and method of application of «GuttaEst-V (L) » (GeoSoft Dent)
device were assessed.
Results and discussion
Temperature change dynamic in different tooth parts can be found on figure
6. Data, collected during laboratory investigation, shows us, that maximal
temperature increase on the external surface of the root during filling process
was found 8mm before apex and equaled +3,8±0,6°C. Thus gutta-percha
was heated up to 109, 2°C. Gutta-percha can be heated and compacted
without chemical structure changes.
Endodontics
E
ndodontics
Accumulated data shows us, that temperature increasing on the external
surface of the root during root canal filling using continuous wave technique
with modern electronic thermopluggers with standard temperature mode is
perfectly acceptable and safe for the surrounding tissues.
Root canal filling technique involving thermoplugger (continuous wave
technique) allows us to ensure fast (on average, 12-15 sec) obturation of
5mm of apical part of the root canal, solving the main endodontic problem
of classical Schilders vertical compaction: decreasing procedure’s length and
complicity.5,11,23 In English publications, this stage is named Down-pack.
As soon, as apical part of root canal is filled, a method of filling the rest of
the canal is to be chosen.
If it is planned to place fiber post, metal screw post or cast pin-stump
construction, it is not required to fill the rest of the canal with gutta-percha.
If the canal requires complete filling, then two options exist. The first one–
using thermoplugger, according to above-described technique. The only
difference is the temperature mode: in this case, the temperature of +100°C
is used. However, this option is laborious, gutta-percha posts may stick to
the plugger at this temperature, therefore majority of dentists prefer to use
injection of warm gutta-percha. Using this technique the middle and cervical
part of the root canal are filled with warm gutta-percha using special injector
(extruder) (fig. 8) with portions of 3-5 mm, compacting them using cold
manual plugger. In English literature, this technique is called Back-Fill.
Fig. 6. Temperature change dynamic in different tooth root parts during
filling using continuous wave technique in laboratory conditions.
It is interesting to note, that switching thermoplugger multiple times inside
tooth canal does not lead to serious temperature increasing on the external
surface of the root (fig. 7). We have found out, that tenfold tharmoplugger
switching on leads to stabilization of the temperature at the level of
+41,3±0,4°C. After that, a long period of tooth tissues cooling down
follows: after single switching on tooth cools down in 16±3 seconds, after
tenfold – in 35±6 sec.
Fig. 8. Extruder for injection root canal filling with warm gutta-percha
«GuttaFill» (GeoSoft Dent).
Conclusion
Fig. 7. Temperature change dynamic in different tooth root parts
in laboratory conditions with one fold and tenfold thermoplugger
switching on.
According to the results of laboratory investigation, and our clinical experience
(Fig. 9, 10), filling root canals using continuous wave technique with modern
Your Guide on the path of Dentistry | GUIDENT
49
Endodontics
E
ndodontics
Mar 2015
endodontic devices is safe and effective. Apprehensions of possible thermal
trauma of periodontal and bone tissues are considered groundless. A wide
application of continuous wave root filling technique in practical dentistry is
highly recommended.
Fig. 9. Clinical cases of tooth root filling using continuous wave
technique.
Fig. 10. Endodontic retreatment: tooth 2.5 – anchor post removed; canal
filled using continuous wave technique on ½ of its length, empty space
left for cast post & core construction. channel is sealed by a continuous
wave 1/2 length , leaving room for a pin - cast copings .
The «GuttaEst-V (L)» (GeoSoft Dent) device we used in laboratory investigation
is easy to operate, ergonomic, has a great price/quality rate and does not give
up on the clinically important and exploit quality compared to foreign devices.
In our opinion, it is important to note the following advantages and additional
options of this device:
XX Cordless,
ergonomic design for simplifying work in root canal;
XX Additional option of vibration of the plugger, which provides better gutta-percha
compacting;
XX The
option of intracanal activation of the irrigating solution;
XX Bright
working area highlighting with a white LED (modification «L»);
XX Accessible
and fast service maintain.
Besides, we consider expedience to widely use «GuttaEst-V (L)» in teaching
process on all stages of pre- and postgraduate education.
Reference
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GUIDENT | Your Guide on the path of Dentistry
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