Measurement of occlusal load

Occlusal load was measured with Dental Prescale and analyzed with Occluzer. The Dental Prescale system allows occlusal contact pressure to be measured quickly and easily across the dentition, and it is of enormous clinical utility because its accuracy and reproducibility in the molar region have been confirmed. The technique using this sequence and also the method of cross-checking occlusal contact points using silicone and Dental Prescale are clinically useful and have been widely studied and reported.

Comparison of occlusal contact areas evaluated using Occluzer and BiteEye

Blue Silicone with a thickness of 10 μm and Dental Prescale gave similar values for the occlusal contact area at 40 and 60 % MVC. These results probably have more validity than those reported by Imamura et al..

Analysis of implant region

Occlusal load on implant region

An occlusal load of approximately 130 N on the first molar has been reported at maximum clenching strength in healthy, dentulous subjects. In the present study, occlusal load on the mandibular first molar was somewhat less, at 81.2 ± 41.1 N. However, bearing in mind that the subjects in the prior study were in their 20 s whereas those in the present study were of middle to old age, with a mean age of 49 years, the present results are probably somewhat valid. Implant prostheses probably have greater occlusal load than natural teeth at higher clenching intensities because they lack the mechanical buffering function of the periodontal membrane. A study using two-dimensional finite element analysis on the mandibular first molar by Maezawa et al. suggests that even if the occlusal surface of the prosthesis is made lower than the occlusal plane, the implant area may still be subjected to excess occlusal load with increased clenching strength.

In the present study, however, the occlusal load on the implant prosthesis tended not to increase as much as the load on the contralateral tooth when the clenching strength was higher. A possible reason is that the dentists adjusted the implant prostheses with pressure displacement in mind, giving a smaller occlusal contact area so that there were fewer loading points than in the contralateral tooth.

When considering the balance of occlusal load in the molar region, it is better to give the same occlusal load on both molar regions at 100 % MVC. However, in this study, the occlusal load was significantly smaller on the implant prosthesis than on the contralateral tooth at 100 % MVC.