Radiographic comparisons of condyle-fossa relationships during maxillomandibular registrations made by different methods

Functional Assessment of the Stomatognathic System, after the Treatment of Edentulous Patients, with Different Methods of Establishing the Centric Relation

The study compares subjective experiences of patients, wearing complete dentures. Two different methods of determining a centric relation were performed: the traditional method using wax occlusal rims and the Gerber method, based on gothic arch tracings. The success rate of establishing a centric relation in both methods was evaluated (rentgenodiagnostics). The influence of the method used to obtain the centric relation on patients' stomatognathic system (condyle centralization, pain) was also evaluated. Better results were achieved in gothic arch tracing method. Before every prosthetic treatment of edentulous patients, a functional analysis of the TMJ is necessary. The lack of centric relation, in a long term adaptation patients, does not lead to TMD symptoms. This trial is registered with NCT03343015.

Quantitative and subjective analysis of temporomandibular joint radiographs

The lateral oblique transcranial radiograph of the temporomandibular joint is commonly used in dentistry. Changes in horizontal angulation of the x-ray beam can produce changes in radiographic condylar position. This study used quantitative and subjective methods to assess and rank changes in radiographic condylar position as a function of known horizontal x-ray beam changes. Six dry skulls were positioned in a craniostat device where known angulations could be measured. Nine sequential transcranial temporomandibular joint radiographs were made of each joint and five of these 12 sets were randomly selected for analyses. The quantitative method involved film digitization, computer calculations, and expressed condylar position as a ratio between posterior and anterior joint space distributions. Eight observers viewed the same films and ranked radiographic condylar position from anterior to posterior. The two methods agreed with known rankings 81.8% of the time. Subjective rankings were more variable than quantitative rankings. Intraobserver differences were insignificant and the observers were consistent among themselves as a group.

Centric relation determinations: clinical and radiographic comparisons

This study investigated variations in occlusal prematurities and condylar positions using different methods of determining centric relation. Thirty patients were randomly placed into three groups of 10. In Group I a clinical analysis of occlusal patterns using bilateral mandibular manipulation (BMM) was compared to results with a chin point (CPM) method. Group II compared CPM to an anterior guidance jig (CPJ) method. Group III compared BMM to CPJ. Standardized transcranial oblique radiographs were taken of each temporomandibular joint using CPM and BMM on 10 patients. Condylar position was determined with tracing evaluations and direct measurements of the radiographs. Clinical results indicated that the initial point of contact was located most accurately with CPJ. Both initial contact points and secondary points were disclosed with CPM. The BMM disclosed the most tooth contacts. Contacts were most prevalent on the premolars. Radiographic analyses of condylar positions were inconclusive.

A method for quantitatively determining temporomandibular joint bony relationships

The spatial relationship of the mandibular condyle to the temporal component of the TMJ is determined quantitatively from lateral tomograms using a new method of measuring specific areas of the joint space. Condyle position along the posteroanterior axis of the joint is expressed as a ratio of the posterior joint space area divided by the anterior joint space area (the P/A ratio). A description of the method, as used in a clinical evaluation of 50 asymptomatic tMJs, and a statistical evaluation of the method's reproducibility and accuracy are given. The method was found to have both high reproducibility and high accuracy.

Centric relation: a comparison of muscle-determined position and operator guidance

Fifteen subjects were used to determine direction and magnitudes of shifts in condylar position when interocclusal records were made by biting hard or easy on a leaf gauge or wax. Electromyographic recordings were made of the temporal and masseter muscles during interocclusal registrations to determine which muscles were most active in seating the condyle when the leaf gauge was used. Results indicated no significant difference in condylar position superoinferiorly between registrations. Biting hard on a leaf gauge caused a significantly more posterior position of the condyle. When this technique is used for obtaining interocclusal registrations, the temporal muscles are more active than the masseters.