[Reproduction of interocclusal relationship on stone casts]

We fabricate a prosthesis by the indirect method. To fabricate a prosthesis functionally harmonized with the stomatognathic system, the interocclusal relationship must be reproduced on stone casts as accurately as possible. In this study, two subjects (one male, age 28; one female, age 31) were selected, and the occlusal contacts of complete arch stone casts made by three different impression methods were observed and compared with the true occlusal contacts in the intercuspal position in the mouth. To take the interocclusal records, we used a silicone bite checker. The following results were obtained. The occlusal contact points reproduced on the stone casts made by a conventional custom tray and a stock tray were rather low; that is, the number of occlusal contact points was less, and the size of the occlusal contact area was smaller, than in vivo. The states of the occlusal contact on the casts made by the same method differed from each other. On the bite-impression technique, the reproduction of occlusal contact was superior to that of the others. The shape, area, and number of contact regions under 60 micrometers were similar to contact regions under 30 micrometers in the mouth. There was no significant difference in reproduction between the custom tray and the stock tray. It is likely that the results were due to the distortion of the jaws and periodontal tissue during clenching at the intercuspal position, which could not be reproduced on the stone casts made by both the conventional custom and stock trays.