Occlusal analysis and occlusion restoration in PPMA
1. Introduction
- Any prosthetic reconstruction poses the problem of its occlusal integration. To resolve this problem, only a complete and thorough clinical and occlusal examination allows the practitioner to decide whether or not to maintain the patient’s occlusion.
2. Reminder
2.1. Physiology of occlusion
- Static concepts : DVO- DVR – ELI – RC – OIM
- Dynamic concepts : POSSELT diagram
2.2. Factors influencing occlusion
2.2.1. Anatomical factors:
- The two temporomandibular joints, fixed factors that cannot be modified in the short term, constitute the essential posterior determinants.
- The anterior determinant or anterior guide is constituted by the contacts of the mandibular arch with the upper incisor-canine sector
If this anterior guide is deficient, mandibular movements are influenced by new determinants
- in the sagittal plane: orientation of the occlusal plane. SPEE curve, condylar trajectory and cusp angulation.
- In the frontal plane: Wilson curve, cusp angulation.
2.2.2. Neuromuscular factors
- Neuromuscular balance ensures the coordination and harmonious functioning of all the components of the masticatory system.
3. The ideal occlusion
An occlusion is said to be ideal when it presents:
- A Harmony of the Stomatognathic System
- Pressures and forces are directed in the direction of the tooth axis without the existence of lateral forces
- Absence of interference and prematurity.
- Dental contacts are made by a multitude of points rather than by a surface
- Stable dental position (no malposition)
- Functional anterior guide
- Sagittal offset only or correspondence between ORC and OIM
- Canine function
4. Occlusal analysis
- Occlusal analysis is a set of techniques that accurately determine dental anomalies that hinder occlusion.
4.1. Clinical occlusal analysis
It is carried out based on careful examination:
- teeth, periodontium, curves and planes that they draw.
- From the Opening-Closing Movement
- From the ORC/OIM Slide
- From the IOM Exam: Ask the patient to click their teeth together effortlessly.
- Reproducible OIM: Fast, regular movements; unique, clear sound that conveys reproducibility; no hesitation or slippage.
- Unstable OIM: irregular movements, doubled dull sound indicating sliding or galloping.
- Propulsion
- Laterality
Noticed :
- Patients suffering from functional disorders of the masticatory system, whether or not associated with pain, often present with muscle contractures; functional treatment prior to any occlusal analysis is then essential (occlusal release plates).
4.2. Occlusal analysis on articulator
- It allows to clearly highlight on the articulator the malpositions or occlusal disturbances responsible for erroneous mandibular positions, to materialize a clinically acceptable reference position and to conduct equilibration.
4.2.1. Indication:
This analysis is indicated if:
- Our clinical examination revealed occlusion disorders manifesting as:
- Shelves and TMJ pain
- A land deflection to reach the ICM whose origin in the mouth could not be detected
- Abnormal mobility or significant wear of the teeth
- The case requires extensive prosthetic restorations involving a joint and removable prosthesis affecting a large area of the arch, requiring a change in the pre-existing occlusal scheme or affecting the anterior guide. Therefore, the necessary recordings must be taken and indirect analysis of the occlusion carried out.
4.2.2. Preliminary steps: Taking impressions of the study model Transfer to articulator
4.2.3. Chronology of occlusal analysis:
- Observation of occlusion anomalies in OIM and ORC
- Analysis of DV in OIM and ORC
- Analysis and Balancing of Previous Sectors
- Analysis and Balancing of the posterior sectors: first the lower arch by re-establishing the occlusal plane using the BRODRICK flag method in order to use it as a reference to balance the maxillary arch.
- In propulsion and laterality
5. Occlusal diagnosis
- Only a thorough anamnesis and oral and extraoral examination, supplemented by additional examinations (axiographic, radiographic, etc.) are able to reveal a possible masticatory dysfunction in its various clinical forms. The approach to the patient in this case is multidisciplinary (psychotherapist, physiotherapist, etc.). At his level, the dental practitioner intervenes to relieve the patient by:
- Sedative prescriptions
- creation of an occlusal release splint allowing access with or without pain or muscular reaction.
- Global prosthetic rehabilitation: The participation of the transitional prosthesis is more often necessary to optimize occlusal functions after a possible sedative stage
6. Preprosthetic occlusal arrangements in the partially edentulous patient
- They aim to improve occlusal conditions to facilitate future integration of the prosthesis.
- Several means are at our disposal: Equilibration, orthodontics, maxillofacial surgery, etc. We cite:
- Selective grinding:
- It is an enamel reshaping by subtraction to reduce or change unwanted occlusal contacts.
- Allows you to manage a system without occlusal interference.
- Aims primarily for better occlusal stability rather than creating an ideal occlusion.
- To destination and cannot resolve all clinical situations.
- Occlusal adjustment
- Occlusal adjustment means go beyond selective grinding
- This involves designing new occlusal curves using prosthetics (fixed or temporary), orthodontics, orthognathic surgery
- Global occlusal rehabilitation
- This involves producing a new occlusal pattern according to known occlusal patterns.
- Cases of change in mandibular position, increase in DV and reconstruction of excessively altered occlusal surfaces (bruxism).
7. Restoration of balanced occlusion in PPAM
- The objective of the partial prosthesis is not only to replace the missing teeth but also to achieve a physiological optimum resulting in a balanced occlusion. This involves:
- Neuromuscular control without constraints
- A harmonious distribution of the occlusal load.
To achieve these objectives it is essential to:
- Maintain or restore physiological DV.
- The choice of the mandibular reference position.
- The choice of the occlusal concept.
- Maintain or restore physiological DV.
- Our approach differs from one situation to another and is conducted based on clinical observation which will provide us with answers to certain questions, namely:
- Is DVO defined by at least one pair of antagonistic teeth?
- Do these contacts affect cuspid teeth or anterior teeth?
- Is the DVO as it stands correct, compatible with neuromuscular balance and aesthetically satisfactory?
- Is the DVO supported by one or two existing removable prostheses?
- The choice of the mandibular reference position.
Dental reference: this is the occlusion in maximum intercuspation, it is chosen when the vertical dimension is not altered, meaning that:
- The DVO being ensured by multi-cusped antagonistic couples does not present pathological abrasion.
- Aesthetics and physiology being ensured by normal relationships.
- No CADAM is observed clinically.
Joint reference: the use of centric relation occlusion is required in all other cases and in particular:
- When PPA is opposed to a total prosthesis.
- When a pathology has imposed balancing grinding.
- When the DV is modified.
- Choice of occlusal concept: see occlusal concepts course
8. Conclusion
Occlusal integration of the removable partial prosthesis is an important factor in the success of our treatment of partial edentulism.
Occlusal analysis and occlusion restoration in PPMA
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