Relines and Rebases
Improving the Adaptation of Existing
Dentures
Rebase
• Replacing entire denture base
• Flasking, heat-cured acrylic
• Usually porcelain teeth
Reline
• Resurfacing the tissue surface
• Jig used to maintain vertical
dimension & occlusal contacts with
cold-cure acrylic
Or
• Reprocessing with heat cure
Indications
Denture no longer fits residual ridge
Retention, stability are lacking
PLUS
• Occlusion is acceptable
• Vertical dimension is acceptable
• Denture teeth/gingival contours acceptable
Contraindications
Complaints of a loose denture
DOES NOT,
in itself, constitute evidence of
a lack of fit and stability
Determine Cause of Looseness
• Pivoting on bony structures
- PIP
• Occlusal interferences
- Tactile, articulating paper, remount
• Inadequate posterior palatal seal
- Pull upward & outward on lingual of
canines
Evaluate Cause of Looseness
• Coronoid interferences
– Side to side movements, PI{ P
• Flanges overextensions
– Pull on the cheeks, lips, patient move
tongue
• Tight pterygomandibular raphe
Relines Will Only Solve Retention
Problems Related to Denture Base
Adaptation
Retention problems must be diagnosed
as to their cause
Types of Relines
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•
•
•
•
Processed or chairside
Impression or functional technique
Hard acrylic or resilient
Permanent, temporary
Complete or partial dentures
Processed Acrylic Permanent Complete
Denture Relines
• Make impression for least stable
denture first
• Easier to stabilize the other denture
– Reference for occlusion & vertical
dimension
Impression Technique
Difficult to reline without:
• Encroaching on interocclusal space
• Displacing the supporting tissues
• Altering occlusal contacts
USE CARE
Positioning the Denture
OVD & Occlusion
Adjust Occlusion
• Obtain stable occlusal contacts
• Remount & adjustment may be required
• Assess need for tissue conditioning
Remove Tissue Undercuts
Allows impression to be removed from
cast without breaking cast or denture
Clean the Denture
Border Mold
• Relieve borders 2 mm short of vestibule
• Border mold with compound
• Maxillary posterior border at vibrating
line (indelible stick)
Reduce Tissue Base
• 1 mm if acceptable interocclusal distance
– Use guide grooves
• If interocclusal distance is excessive, relief
may not be required
• Perforate denture with #4 round bur
Impression Material
Polyvinylsiloxane
• Ease of use
• Cleaning, removal from undercuts
• Requires adhesive carried to the external
surface of denture borders
Impression Procedure
• Load carefully
• Excessive material can
reduce freeway space
• Dry tissues
Impression Procedure
• Seat denture anteriorly
• Slowly rotate posterior into place
• Ensure denture is not too far forward
Verifying Position
• Patient closes lightly until first contact
• If occlusal interdigitation is poor,
physically move denture
• Maintain position until set
Evaluate Impression
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•
•
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Trim impression to posterior border
Place / mark the posterior palatal seal
Check retention, extension, periphery
Remove excess (occlusal, facial etc.)
Check relations intraorally
Send to lab for processing
Deliver ASAP, usually next clinic
Same day in practice, if possible
Remount
Adjust Occlusion
Impression Technique
Advantages
• Only two appointments needed
• Tissues are captured at rest
(less possibility of distortion)
• Allows for greater extension of peripheries
• Allows placement of functional posterior
palatal seal
Impression Technique
Disadvantages
• Possible alteration in VDO, occlusion,
facial support
• No chance to test retention and comfort
under function
Functional Relines
(Lynal, Visco-gel)
• Similar procedure
• Minor variations
Functional Relines
• Cannot extend borders greater
than 4 mm
• Distorts too easily
• Grossly under extended, use
impression technique
Functional Relines
• Material requires greater thickness
for accuracy
• Usually need to reduce denture to
allow for thickness
Variation in Accuracy of Materials
(Visco-gel> Coe-Comfort)
Lynal
• 10 ml powder : 2 ml liquid, mix 30 sec
• If borders short or too thin, add more
powder for increased viscosity
• Thicker consistency can be formed into a
3 - 4 mm rope and placed around borders
Lynal
• For tissue base, mix as per instructions
• Place intraorally
• Remove excess with cotton swab prior
to set
Set time: 8-10 minute
• Lightly border mold
• During setting, allow patient to:
– Talk
– Swallow
– Lightly occlude
Remove Excess
• Reduce material on flanges with
HOT scalpel or knife
• Remove from teeth, oral surfaces
• Patient wears reline home
Patient Returns in 24-48 Hours
• A cast is poured within 2 hours
• Otherwise, accuracy compromised
Functional Impression
Advantages
• Functionally molds peripheries
• Ability to assess patient comfort and
retention prior to reline proper
Functional Impression
Disadvantages
• Variability of materials, handling
characteristics
• Resiliency masks overextensions which
can subsequently irritate, when
converted to acrylic resin
Functional Impression
Disadvantages
• Dimensional stability variable
– Patient care
– Pouring of casts
• Can' t significantly increase borders
• Do not use simultaneously as a tissue
conditioner
Partial Denture Relines
• Similar procedures
• Ensure rests, direct and indirect
retainers are fully seated
• Seat with pressure over the rests,
NOT the distal extension bases
Partial Denture Relines
• Allow no impression material under
rests or guiding planes
• If so, remake impression
Partial Denture
Clinical Remount
• If required, a new cast must be made
• Make an alginate impression with the
RPD in place
Partial Denture
Clinical Remount
• Block out undercuts on the
framework while RPD is in the
impression
• Pour the model with the partial
denture in place