Abstract
The purposes of occlusal adjustment of a crown are: to make the crown be harmonious to the dental arch in the intercuspal position; to maintain occlusal pattern in mandibular movements; and to build up numbers of occlusal contact points, contact area and contact sections that are similar to the adjacent teeth.
In the ordinary indirect method, the height of the crown is excessively high as a cast, 200-300μm, at intercuspal position. But, its height is proper only at intercuspal position in accuracy of a few μm, by means of occlusal adjustment using burs, abrasive points and articulating paper.
The aim of this investigation is to find out whether there are occlusal contact points with an accuracy of a few 10μm at intercuspal position and those in each cusp of crown, after occlusal adjustment during lateral and protrusive excursions.
Crowns were made on upper and lower molar teeth for each of 10 subjects. The occlusion of the crowns was adjusted in the ordinary clinical method before cementing by means of observation, tactile sensibility and an articulating paper pull-out test and occlusal contact pattern as index. After occlusal adjustment, the silicone-black method was used for estimating the occlusal contact in the intercuspal position. As for three out of ten cases, the occlusal contact of crowns was analyzed. In trial, temporary cementation and cementing of crowns, and after a week of cementation, occlusal contact patterns were taken on the articulating paper and the silicone-black. They were also observed by microscope and visual scaler.
As a result, occlusal contact sections were located on the incline of cusp or marginal ridges, and occlusal contact points were limited in near contact parts of facets shown on the silicone-black, which were made in occlusal adjustment. In the process of the occlusal adjustment, the number of occlusal contact points were gradually increased and contact areas became smaller.
Conclusions are as follows:
1. It is not necessarily easy to make occlusal contact point on each cusp of crown at intercuspal position.
2. Estimation should be done of the near contact part with relation to occlusal contact.
