[Studies on the occlusal wear of posterior composite resin restorations. Part 1. A measuring method of the occlusal wear of restorations].

A method for measuring the occlusal wear of the restorations was devised newly and its precision was examined. The positive resin replicas of a specially designed metal prototype with a slope and an artificial ivory teeth before and after reducinng the occlusal portion were produced using the silicone impressions. The distance between the given portion of the prototype and the positive replica was almost the same, showing a difference between the prototype and the postive replica immediately after porymerization or after 1 or 2-year storage within 1ƒÊm. The relative error of the positive replica was 0.29%. On the other hand, the silicon-rubber negative replica made from the positive replicas of the artificial ivory teeth were longitudinally sectioned bucco-lingually at the same portion. The occlusal profile was then obtained from the negative replica. The difference between the original occlusal profile and the plofile after reducing was measured. The degree of the precision of this method was thus appraised to be approximately •}2ƒÊm (standard deviation). This would be a reliable method for measuring the occlusal wear of the restorations.