Occlusion in relation to RPD - cases in presentation

Question 1

Why is occlusion important in RPDs?

Answer 1

If wrong - pt will not tolerate the denture

Question 2

Define ICP

Answer 2

The point of maximum intercuspation between the teeth

Question 3

Define centric relation

Answer 3

Relationship of the mandible to the maxilla when the condyles are seated in the midmost uppermost position in the glenoid fossa

Question 4

Centric relation features?

Answer 4

A jaw relationship - nothing to do with the teeth
Optimum position for the neuromuscular system
Reproducible and well tolerated by the pts = useful

Question 5

Define RCP

Answer 5

First tooth contact when the condyles are fully seated in the glenoid fossa

Question 6

Define vertical dimension

Answer 6

Vertical dimension of occlusion or VDO (occlusal vertical dimension - OVD) = indicates the superior-inferior relationship of the maxilla and the mandible when the teeth are situated in maximum intercuspation

Question 7

What to consider before starting your RPD case, regarding ICP?

Answer 7

Is the ICP stable e.g. clear intercuspation between numerous teeth which the pt consistently replicates
If ICP is unstable or unclear = often due to reduced number of tooth contacts or tooth wear and the ICP position is not easy to replicate

Question 8

What to consider before starting your RPD case, regarding vertical dimension?

Answer 8

Stable and acceptable?
Will not be stable if there are no remaining tooth contacts (e.g. if remaining teeth do not oppose each other)
Not acceptable in tooth wear cases where there is significant loss of tooth height or where space is required to fit components of the denture such as the major connector or denture teeth

Question 9

What to do if the ICP is unknown/unstable but the vertical dimension is acceptable?

Answer 9

New ICP needed to be established to coincide with centric relation
= establish new occlusal scheme on registration rims and articulate the models

Question 10

What to do when the ICP is stable but the vertical dimension is unacceptable?

Answer 10

Registration rims to establish a new ICP at the correct vertical dimension to be coincident with centric relation

Question 11

What to do when ICP is unknown and the vertical dimension is unacceptable?

Answer 11

Registration rims to establish new ICP at the correct vertical dimension to be coincident with centric relation

Question 12

What to do when the ICP is stable and vertical dimension is stable?

Answer 12

Make a mucosa borne denture with study model aids

or tooth borne denture = consider the position of occlusal rests = articulate the models prior to designing

Question 13

How to make an RPD?

Answer 13

Primary imps - survey and design denture
Tooth prep and 2ndry imps
Registration
Try-in
Fit
Review

Question 14

How to design the denture?

Answer 14

Primary imps
Survey the casts
Check how teeth occlude so that no aspects of denture interfere with occlusion
- Articulate casts by hand if the occlusion is obvious
- If ICP is stable but not obvious on the casts = take silicone bite registration at the time of primary impressions
- Registration rims and record occlusion if it’s not obvious when holding the casts together = another visit

Requires surveyed and articulated study casts
Then tooth prep and 2ndry imps

Question 15

What to consider with tooth prep and 2ndry imps?

Answer 15

Rest seats - make sure they’re cut to appropriate dimensions
= Needs to be enough space for the rest without affecting the occlusion
Leave enough space for the minor connector or clasp arm
Ensure rest seat preparations are picked up well by 2ndry imps

Question 16

Stages of the framework try in (co/cr only)?

Answer 16

Check metal framework fits well on the cast and is fully seated
Then transfer to mouth and ensure the framework fully seats - pay attention to rest seats
Then check occlusion - if conforming to current ICP make sure the occlusion is not altered
If required, adjust until the framework seats fully and does not interfere with the occlusion

Question 17

Wax registration features?

Answer 17

On a wax/shellac/acrylic base for acrylic dentures
Should be on the metal framework for a co/cr denture
Confirms occlusal relationship and tooth position, incisal plane

Question 18

Wax try in features?

Answer 18

Ensure the occlusion is identical to the wax registration
If there are discrepancies make adjustments
Last stage to make changes

Question 19

Fit features?

Answer 19

Check no changes to the occlusion from the wax try in stage
Make adjustments required
Check record?

Question 20

Features of metal backings?

Answer 20

May be provided with co/cr dentures
If so, do a tooth try in at this stage to tell the technician where the denture teeth and metal backings need to be
= another visit