Occlusal concepts in PPA

Occlusal concepts in PPA

Introduction
Definition
- Rules establishing the number and location of contacts for the meshing of teeth and sliding surfaces for the reference position and during excursion movements of the mandible.
Objectives of occlusal concepts:
- Effective occlusion with precise and stable contacts
- Patient comfort when chewing without fatigue and pain
- Mutual protection of the constituents of the masticatory system:
- The proprioceptive system protects the occlusion which limits functional demands.
- The front teeth protect the back teeth.
- In addition to mutual support of the structures between them for freedom of movement (the condyles are protected by the front stop of the incisors, by the lateral stop of the canines and by the rear stop of the PM)
- Protection of teeth, muscles, ATM

Sustainability:
- From the PPMA
- A stable posture to maintain oral health
- A beautiful smile
- Structures of the masticatory system

The different occlusal concepts:
- Once the examination of the occlusion, in the mouth and on the articulator, has been completed, any occlusal corrections have been made and the guiding curves restored, the practitioner must choose the most appropriate occlusal concept:
- Balanced occlusion
- Canine function
- Group function
Occlusal concepts:
- Occlusion with canine protection: The gnathology concept: Concept of canine contact (Mac Collum gnathology school)
- In RC:
- The contacts of the posterior sectors are firm and the contacts of the anterior sector are light.
- The maxillary canine has the strongest periodontium due to these characteristics, the canine function is considered the ideal lateral function.

Laterally:
- On the working side; the only contact that exists is between the vestibular surface of the lower canine and the palatal surface of the upper canine.
On the non-working side: There is no contact.
In propulsion: the six antero-inferior teeth slide on the palatal concavities of the upper incisors, there is disocclusion of the cuspid teeth.
Interdental relationships: the contacts are of the tooth-to-tooth or cusp-fossa type. When, laterally on the working side, one or two incisors are associated with the disengagement phenomenon, this is an occlusion with anterior protection.

5.2. Occlusion with group function : The functionalist concept: Concept of group contact (Pankeymann-Schuyler functionalist school)

In RC: all teeth are in contact.
Laterally:
On the working side: there is contact of the cusped teeth by the internal slopes of the upper vestibular cusps and by the external slopes of the lower vestibular cusps.
Non-working side: there is no contact between the teeth.
In propulsion: the six antero-inferior teeth slide on the palatal concavities of the upper incisors, there is disocclusion of the cuspid teeth.
Interdental Report: the contacts here are also of the one-tooth-two-tooth type (cusp marginal ridge) this occlusion can be designed with the starting point of the RC or maximum intercuspidation.

5.3. Balanced bilateral occlusion :

In RC: all teeth are in anterior and posterior contact.
Laterally:
On the working side: there is contact of the cusped teeth by the internal slopes of the upper vestibular cusps, by the external slopes of the lower vestibular cusps.
On the non-working side: there is contact by the cusped teeth by the internal slopes of the palatal cusps, by the internal slopes of the vestibular cusps of the lower teeth.
In propulsion:
There is contact of the incisor-canine groups and simultaneously contact between the cuspid teeth and at least this contact is made by the meo-platinum cusp of the last upper molar which touches and slides on the marginal ridge of the last lower molar.
Interdental relationship: the contacts are of the two-tooth type, therefore cusp-marginal ridge. This is the classic occlusion of the complete denture; in this type of occlusion, all the teeth come into contact in all mandibular movements.

This choice varies depending on a number of factors:

The type of edentulism of the treated arch

6.1. The nature of the antagonistic arch:

When a PPA is opposed to a total prosthesis, the priority being the stability of the complete prosthesis, the occlusion will then be balanced bilaterally. In such a situation, the vertical forces are transmitted to all the bearing surfaces and the lateral forces are distributed on both sides of the arches.

6.2. The extent of the tooth loss:

When the edentulism is small, the possibility of only involving the remaining teeth in mandibular guidance is real. This diminishes when the edentulism is more extensive.

6.3. Distribution of remaining teeth

On a partially edentulous arch, eccentric antagonist contacts may or may not be unbalancing for the PPA.
- If they are established on the remaining teeth, they are not unbalancing.
- If they are distributed between natural and prosthetic teeth , they are rarely unbalancing.
- If they are established only on the prosthetic teeth , they are unbalancing.

6.4. Periodontal value

The participation of a tooth in an eccentric movement of the mandible is directly related to its periodontal value

6.5. The quality of the previous guide

An effective anterior guide allows the choice of the concept of disocclusion by the canine because it eliminates the tangential forces on the cuspid teeth.
A deficient earlier guide, associated with a significant BENNET movement oriented towards the concept of group function.
An absent anterior guide associated with significant edentulism requires a bilateral balanced occlusion.
The restoration of the anterior guide by the removable prosthesis has opposite consequences depending on the maxilla:
- In the upper jaw, any contact in the anterior region is destabilizing because it causes a rotational moment around the axis joining the occlusal stops bordering the gap.
- At the mandible the moment of force is reversed and stabilizing.

5th year PPMA course

academic year 2021/2022

Whenever the residual dentition allows it, the concept of canine protection will be used. This concept will be achieved by the natural or similar teeth (fixed prosthesis) in a favorable paradoxical context because it helps prevent any instability of the PPA.
If the paradoxical context is unfavorable, group contact will be sought in order to relieve the canine.

Occlusal concepts in PPA

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