Minoru Ai

A SHORT-TERM CLINICAL FOLLOW-UP STUDY OF SUPERPLASTIC TITANIUM ALLOY FOR MAJOR CONNECTORS OF REMOVABLE PARTIAL DENTURES

STATEMENT OF PROBLEM Superplastic forming of Ti-6A1-4V alloy has been used in the fabrication of a removable denture framework. The method provides the titanium alloy denture framework with excellent physical properties not seen in cast titanium prostheses. PURPOSE This study describes the technical procedure for fabricating removable dentures with this type of framework and evaluates clinical applications of the dentures in short-term follow-up periods from 6 months to 3 years. RESULTS Results of this study demonstrated that the dentures functioned well and did not cause any major clinical difficulties. The patients have expressed satisfaction with the dentures at regular recall appointments. CONCLUSION The clinical observations suggest that this method is suitable for fabricating titanium alloy removable dentures.

Tenderness on palpation and occlusal abnormalities in temporomandibular dysfunction

Tenderness on palpation indicates objective painful symptoms. This study investigated the tenderness of the temporomandibular joint, muscles and their relation to occlusion in patients with temporomandibular dysfunction. Two hundred ten patients were examined; 96% had tenderness and 80% of cases of tenderness were diagnosed as occlusally related. The average number of tender areas was 5.4 per patient, despite the contribution of occlusion. Tenderness was observed most frequently in the lateral pterygoid muscle, followed by the insertion of temporal muscle. There was no correlation of temporomandibular joint tenderness to muscle tenderness, while tenderness of certain muscles to each other was correlated. Differences were related to the state of occlusion in the number of tender areas, to the ratio to tenderness of elevator muscles to horizontally acting muscles, and to the frequency of unilateral tenderness. The association of muscle tenderness and occlusion was suggested.

Influence of Alteration of Tooth Contact on Mandibular Displacement during Lateral Clenching.

To investigate the relationship between occlusal scheme and joint loading, mandibular displacement was measured during lateral clenching under experimentally altered occlusal conditions. Acrylic occlusal devices were fabricated for the lower working-side canine, working-side second molar, and balancingside second molar. With the aid of these devices, various occlusal states were simulated. Eight healthy subjects volunteered for this study and performed clenching tasks. Vertical displacements of the mandible were recorded by linear variable differential transformers, and the results were as follows:1. Clenching efforts in the lateral mandibular position caused elevation of the mandible.2. When a single occlusal device was placed unilaterally, the amount of the upward displacement near the supporting tooth tended to be smallest.3. Insertion of three occlusaldevices (bilateral tooth contacts) reduced the amplitude of mandibular displacement.These results suggested that the nature of reaction forces at the temporomandibular joints caused by the elevation of the mandible would be influenced by the occlusal status.