Denture Relining & Rebasing
Denture Relining:
Addition of relining material to the tissue side of a
denture, to improve its adaptation to the supporting mucosa (resurfacing
the tissue surface).
Reline Indications:
1. Loss of retention
2. Instability
3. Food under denture
4. Abused mucosa (use conditioning material)
5. In addition to improve lack of fit to the supporting tissue
6. Relining may be combined with:
7. Improving border extension (depth and /or width) or provision of a
post dam.
8. It cannot correct errors in tooth positioning.
Rebasing Indications:
1) Porous or artifact of the denture base
2) Loss of retention & stability
3) Should have correct jaw relations
Relining / General Considerations:
1. Optimal tissue health
2. Reasonable CR/CO
3. Adequate vertical dimension
4. Adequate peripheral extensions
5. Also relining cannot be used when
a. No free way space.
b. Lack of balanced occlusion and articulation.
c. Non-alignment with optimal denture space.
d. Incorrect contour for neuromuscular control.
Patient and denture pre-requisites for relining:
1. Tissues must be in normal healthy state.
2. The denture must be able to be stabilized by border refining.
3. There must be reasonable centric occlusion in harmony with centric
relation.
4. There must be at least correctable rest vertical dimension and
occluding vertical dimension.
5. Absence of speech defects (possibly whistling can be corrected).
Types of Relines:
Can be classified as…
• Processed or chair-side
• Static impression or functional technique
• Hard acrylic or resilient
• Permanent, temporary
• Complete or partial dentures
Relining techniques:
Mainly:
Direct method (chair-side relining material):
Indirect method / Conventional (processed relining material),
which is subdivided to :
Static impression.
Functional impression.
Direct method (chair-side relining material):
Make by…. cold cure Or conditioning materials.
Indications:
1. Where no longer than 6 weeks is required.
2. Around over-denture abutments.
3. Border additions.
4. For RPD base areas.
With drawer points:
1. As it deteriorates in oral environment, so it can’t be used for long term
service.
2. The material is difficult in adhering to denture base.
3. Tissue surface is rough and presents porosity & cause bad odor.
4. Color stability is of short duration.
5. If denture is not properly positioned, correction is difficult.
6. Tissue irritation may be caused by lysis of the local monomer, or burn
mucosa during polymerization.
7. Exhibits more dimensional changes.
Technique:
The denture is cleaned, roughened, and slightly reduced. The flanges are
trimmed (to reduce danger of over extension) and the undercuts removed.
The new relining is then mixed and applied to the fitting surface. The
denture is inserted and the patient asked to bite gently on the denture to
ensure that the occlusion is not altered by the procedure. Border molding
can then be carried out.
The denture is kept in site for about 5 minutes after which it is removed and
carefully examined. If cold cured acrylic was used the denture is placed in a
hydroflask to complete the curing and to reduce the possibility of porosity. If
tissue conditioner was used then the excess should be trimmed away and
re-inserted. This should be carried out a couple more times to make sure the
all of the excess is removed.
Indirect method/ Conventional (processed relining material)
The ZOE or light body used mostly with this procedure…
Technique:
Clean the denture for maximum bond strength, even use ultrasound.
device.
Then take VD at rest and at occlusion: to avoid changing the smile line and
& lengthening the incisors or showing acrylic (esthetic considerations), as
well as prevent alteration of the vertical measurements of the patient
(functional considerations). Check the Centric occlusion before & after the
lining impression would be taken.
Now remove the tissue undercuts to allow impression to be removed
from cast without breaking cast or denture
Shorten the denture flanges to provide room for the impression material;
special burs can be used to ensure a uniform reduction of flanges. Also put
vent holes at internal surface to ensure the perfect positioning of
impression, and to prevent separation of impression material from the
denture.
Loaded the impression material, a thin layer of impression material is
spreads in all around the fitting surface on the denture. (Avoid voids)
Sure the uniform thickness of impression material & correct position to
prevent alteration of VD or occlusion.
Remove the excess impression material to improve the impression
borders and to decrease needing for trimming & finishing the borders. Then
a right positioning for the opposite prosthesis is ensured {to ensure
maximum inter cuspation you can ask the patient to close his mouth at
correct CO at correct VD, by this the impression converted to close mouth
technique}.
Selective impression Technique for relining:
By border molding first with keeping correct VD. Then make spaced
impression on the abused mucosa & leave the primary bearing areas (or
areas want to receive the occlusal loads) as stoppers, on the fitting surfaces.
Then take the impression.
Continue the laboratory steps by usual way…
Hard Relining:
Cold & hot cured acrylic included by this relining classification.
Aims: Provides even contact between the impression surface of a denture
and its supporting tissues, thereby improving retentive forces and support.
Resilient soft linings:
Silicon lining or conditioning materials are used as resilient liners.
Aims: to absorb the impact energy of the masticatory forces and distributes
it more evenly over the supporting tissues.
Indications of the soft lining:
a. It is most effective when used over corticated bony elevations.
b. Use to improve retention by engaging undercuts.
c. Not advised where mental neurovascular is superficially placed.
Disadvantages of soft lining:
1. Tend to peel off the hard acrylic denture base (acrylic material adhere
better).
2. Difficult to adjust (acrylic materials more easily altered).
3. Porous, tending to absorb fluids )with resultant swelling and bad
odor) due to harbor bacteria and fungi.
4. Need more thickness to be effective this may be weaken the denture,
especially the lower denture.
5. Rapidly deteriorate.
6. Some patients can become habituated to such linings and cannot be
satisfy with hard tissue surface.
7. Rub the oral mucosa since they deform under masticatory pressure.
RPD Relines
(Open mouth technique for relining)
:
1. Similar to an altered cast impression.
2. Materials of choice are ZOE wash, or impression wax wash.
3. It preferred to take over-all impression with reline in its place in
mouth and the cast is poured, put your fingers on main occlusal rests
and indirect retainer.
4. Note that the teeth relation to opposite ones not altered.
Note: Even you can add teeth on relined denture.
Rebasing:
The technique is the same as for reline except in the laboratory
steps, the palate is removed and a new one waxed in before
processing.
Also a plaster index must be made in the opposing member of the
articulator, to ensure repositioning of the teeth in after separation
them from the base (that will be altered), then complete the waxing
up & flasking.
Thank you…..dr. Monia