Occlusal integration of the prosthesis
introduction
In removable partial prosthesis, the occlusal integration of the prosthesis is an important factor for success.
Any prosthesis must be integrated into a complex structure that constitutes the masticatory system.
Occlusal integration involves:
– Evaluation of occlusal curves;
– The choice of dental or articular references for recording the intermaxillary relationship;
– The choice of the occlusal concept.
The choice of the occlusal concept must be made when developing the treatment plan.
factors to consider in choosing the kinematic occlusal concept:
The practitioner must choose the most appropriate occlusal concept:
- balanced occlusion;
- canine function;
- group function.
This choice varies depending on a number of factors:
- the type of edentulism of the treated arch;
- the extent of the edentulation of the treated arch;
- The maxilla considered.
- the value of the canine sector;
- the value of the incisive sector.
Kinematic occlusal concept according to the edentulous class.
The requirements related to the fixed prosthesis or natural teeth and those related to the total removable prosthesis must be taken into account.
The goals of occlusal schemes are comfort, mutual protection, and durability.
Three principles are essential for determining occlusal schemes
- find a stable, reproducible dental position for the patient (the OIM or ORC);
- develop a function with mutual support of structures for freedom of movement.;
- restore the smile.
Occlusal integration of the prosthesis
Occlusal concepts :
- The different occlusal concepts:
Three main concepts govern how teeth should or should not contact during various functional and limiting mandibular movements; these are: balanced occlusion, group contact, and protected mutual occlusion.
- Bilateral balanced occlusion:
Based on the work of Von Spee and Monson, this concept is less used today than in the past. Essentially prosthetic, it postulates that a maximum number of teeth must establish contact in all excursions of the mandible. The notion is particularly interesting in complete dentures, where contacts on the non-working side are required to prevent tipping of the prostheses.
Later, the concept was extended to the occlusal reconstruction of natural dentition, with the intention of reducing the load applied individually to some teeth by distributing the efforts over the greatest number. But, given the difficulty of such an undertaking and the excessive wear by friction caused by the multiple dento-dental contacts occurring during the various movements of the mandible, the idea was abandoned.
- Unilateral balanced occlusion or group function:
Concept widely accepted and used in prosthetics.
The origin of this concept lies in the work of Schuyler and Coll, based on observations revealing the destructive nature of dento-dental contacts on the non-working side (NT). For them, balanced occlusion is not necessary in natural dentition; it is appropriate to eliminate any non-working contact in prosthesis.
In reduction, contact at the level of all the teeth on the working side (T) is therefore sought. This group concept aims to distribute the occlusal load.
The absence of contact on the NT side is intended to prevent the teeth from being subjected to destructive oblique forces, the support cusps are protected from wear and the maintenance of occlusion over time is more evident.
The FGP (functional induced pathways) technique, which will be described later, is the method of choice for obtaining prosthetic constructions that establish group contact.
Occlusal integration of the prosthesis
- Mutually protected occlusion:
Also called: “canine protection” or “ organic occlusion ” or even “gnathological occlusion”. It is highlighted by the gnathology society.
In this type of occlusion relationship, the anterior teeth protect the cuspid teeth in all mandibular excursions, and the cuspid teeth protect the anterior teeth in ICM; hence the term mutually protected occlusion.
- In such an occlusal context, it is essential that the periodontal support of the anterior teeth be strong.
In case of bone lysis at the level of the anterior group or in the absence of canines, the arches must be reconstructed with group contact.
- The indication for mutually protected occlusion also depends on the type of inter-arch relationships. In Angle class II and III, for example, anterior guidance does not exist. It is also contraindicated in cases of reverse occlusion:
maxillary and mandibular vestibular cusps interfering in working laterality.
- Different types of occlusion:
- Different types of occlusion: There are different types of occlusion depending on the contacts established in RC in propulsion and laterality:
C- Choice of Occlusal Concept:
Several elements come into play in this choice:
- 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 on all the bearing surfaces and the lateral forces are distributed on both sides of the arches.
- The extent of tooth loss:
- on a partially edentulous arch, the eccentric antagonist contacts may or may not be unbalancing for the PPA.
-If they settle 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.
3- The quality of the previous guide:
- If the anterior guide is effective, capable of supporting the occlusal load, the anterior guidance in propulsion, the canine function in deduction is desirable, because it eliminates the tangential forces on the cuspid teeth and on the crests.
- If the anterior guide is deficient with a diminished periodontal value, this anterior guide imposes the choice of occlusion according to group. The group function will be sought, in order to relieve a canine not having a good extrinsic value,
- An absent anterior guide requires the choice of balanced bilateral occlusion.