Three Dimensional Evaluation of Discrepancy between Maximum Intercuspal Position and Centric Relation

Vashi, Shailendrasinh (2011) Three Dimensional Evaluation of Discrepancy between Maximum Intercuspal Position and Centric Relation. Masters thesis, Ragas Dental College & Hospital, Chennai.


Download (4MB) | Preview


INTRODUCTION: The search for the optimal and preferred types of static and functional occlusions has occupied the minds of dentists for more than a century. The possible role of occlusion in the aetiology of temporomandibular disorders (TMD) also has been the subject of debate. Much of the occlusion/TMD debate involves issues surrounding centric relation (CR), including definition, recording and measurement, use of articulators and deprogramming splints, and possible relationship to either stomatognathic health or disease. Over the years, many methods have been developed to study the TMJ and the condyle position in the joint space. Some of the conventionally used methods are radiographs, laminographs, tomograms, and magnetic resonance imagings. However, these are not without their limitations as they present only anatomical parameters and ignore the extremely dynamic functions of this complex joint system. The centric jaw relation (CR) position, in the naturally dentulous state does not usually coincide with the position the mandible assumes when the teeth are in centric occlusion (CO). Historically, centric relation jaw position has been defined as the most "retruded” contact position, but current research indicates that the correct definition is "the relation of the mandible to the cranium that exists when the condyles articulate with the thinnest avascular portion of the respective discs in their most anterior superior position against the slopes of the articular eminences regardless of tooth contact. Stability is one of the treatment goal of orthodontic treatment, and to get to that, a gnathological approach is necessary. Establishing equilibrium between the teeth and the neuromusculature is critical because whenever there is disequilibrium, the muscles will attempt to regain it. The evidence of this is excessive tooth wear, tooth hypermobility, periodontal break down in the presence of good oral hygiene. If treatment goals include condyles seated in the fossa and an occlusion that will not interfere with condylar border movements, then it is essential to assess the occlusion with the condyles in centric relation. This study was thus conducted with the aim of establishing the discrepancy between Maximum Intercuspation (MI) and Centric Relation (CR) in post orthodontic patients and to statistically evaluate the range of deviation from the accepted norms. MATERIALS AND METHODS: The study group consisted of 30 subjects with the following criteria. 1. All of them treated by post-graduate students in the Department of Orthodontics, Ragas Dental College, Chennai. 2. These subjects, 18 females and 12 males ranged in age from 14 yrs to 25 yrs. 3. None of them had any relevant medical history. 4. Both extraction and non-extraction cases were included. 5. No temporomandibular joint signs or symptoms were present before treatment. 6. All of them were treated using .022 Roth Ovation brackets with atleast 6 months in retention. Methods: 1. Impressions were taken using Alginate impression material and poured using hard dental stone. 2. The models were trimmed and all air bubbles removed from the surface. 3. The facebow records were taken on each patient using the SAM (Great Lakes orthodontics, NY, USA.) anatomic facebow system. RESULTS: 1. From the data obtained from MPI readings, a statistical analysis was employed to determine the percentage of the sample population with a difference between CR and MI. 2. A Student’s t-test was performed. The hypothesis being tested was that either there is a significant difference between MI and CR or, there is no significant difference. 3. The statistical analysis was carried out in two parts. The first part tested the obtained values within the two groups, i.e. Extraction and Non-Extraction. 4. The second part tested the obtained values between the same group, i.e. either Extraction or Non-Extraction. 5. The level of statistical significance was set at p=0.05. 6. If the value of ‘p’ › 0.05, then the inference is that there is no statistical difference between the variables being compared. 7. However, if the value of ‘p’ ‹ 0.05, then the inference is that there is a statistical difference between the variables being compared.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Three Dimensional Evaluation ; Discrepancy ; Maximum Intercuspal Position ; Centric Relation.
Subjects: DENTAL > Orthodontics and Dentofacial Orthopedics
Depositing User: Kambaraman B
Date Deposited: 12 May 2018 09:34
Last Modified: 12 May 2018 09:34

Actions (login required)

View Item View Item