[New estimation method for displacement characteristic of teeth with occlusal force records]

To establish adequate occlusion for prostheses, evaluation of degree of displacement of teeth and implant is essential. However, it cannot be attained without complex equipment, which limits clinical application. To develop a new estimation method for displacement characteristic of teeth and implant by both occlusal force of individual teeth and existing data on degree of displacement, the relationship between increase of total occlusal force and occlusal force of individual teeth was evaluated.

Ten male subjects (mean age: 28.5, [range: 26-31] years) with clinically normal healthy dentition were selected. Electromyograms at maximum clenching at intercuspal position were recorded as 100 MVC. Then, clenching at 80, 60, 50, 30, 20, and 10 MVC was instructed with visual feedback. Occlusal forces were recorded with pressure-sensitive sheet (Dental-Prescale). The occlusal contacts were recorded by a silicone occlusal contact checking material (Black Silicone). The change of occlusal forces at first premolar was converted to displacement with existing data of degree of displacement (Goto et al). Then displacement characteristic of second premolar and first molar was calculated.

The displacement characteristic of second premolar was similar to existing data on first premolar. Although the displacement characteristic of first molar was similar, the degree of displacement was small, which means occlusal force at the first molar increased more than at the first premolar as increase of the displacement.

The results of this study, indicating similarity to past studies with complex equipment, suggest that the displacement characteristic of teeth could be estimated with both occlusal force of individual teeth and existing data on degree of displacement.