Hideaki Okane

Changes in retention of various telescope crown assemblies over long-term use

An investigation was done on the effect of crown height, angle (one-half taper) and number of removals on the retention of telescope crowns. Assemblies of inner and outer crowns were constructed on master dies. Crown heights of 4 mm, 5 mm, and 6 mm were used. Cone angles of 0, 2, 4, and 6 degrees were used for each of the three heights. The inner crowns were fixed to the dies with an adhesive agent. the outer crowns were set over them and placed in a clamp. Separation forces were tested with an Instron machine (Instron Corp., Canton, Mass.). They were measured initially and after numerous 100 insertion/separation cycles up to 1000 cycles and numerous 500 insertion/separation cycles up to 10,000 cycles. The results demonstrated that the cone angle of the inner crown was more important than its height for maximum retention. Retention is rapidly lost after the cone angle exceeds 2 degrees. It was also shown that an accessory device is necessary to maintain retention capabilities after long-term use.

The effect of anteroposterior inclination of the occlusal plane on biting force.

With the experimental design of this study the following conclusions were reached. 1. Biting force during maximum clenching was the greatest when the occlusal plane was made parallel to the ala-tragus line. It decreased when the occlusal plane was inclined about 5 degrees anteriorly or about 5 degrees posteriorly. 2. The efficiency of biting force exertion during maximum clenching showed the best value when the occlusal plane was made parallel to the ala-tragus line. 3. Muscle activity during clenching at various given forces was least when the occlusal plane was made parallel to the ala-tragus line. The anteroposterior inclination of the occlusal plane tends to affect the biting force, and the method with the ala-tragus line seems to be the most reasonable for occlusal plane orientation.

The role of the periodontal ligament in overdenture treatment

The results of this experiment suggest that the periodontal ligament plays a role in the efficiency of muscular activity during chewing in patients wearing overdentures. A masticatory index as an indicator of the efficiency of masticatory movement is proposed in this research.

Precise discussion of time-reversal asymmetries in B-meson decays

A bstractBaBar collaboration announced that they observed time reversal (T) asymmetry through B meson system. In the experiment, time dependencies of two distinctive processes, B−→B¯0

A Physiological Study on Occlusal Plane of Orientation

{B}_{-}\to {\overline{B}}^0

A criterion for the selection of artificial posterior teeth

and B¯0→B−

The Effect of Denture Base Area on Biting Force Exertion

{\overline{B}}^0\to {B}_{-}