Measurement of occlusal contact area of implant prosthesis

Dental Prescale has a thickness of approximately 100 μm, whereas Blue Silicone has less thickness and is therefore likely to give more accurate measurements of the occlusal contact area. In addition, when the occlusal contact areas of implant prostheses and their contralateral teeth were compared, the occlusal contact area of the contralateral teeth was significantly greater at higher clenching strength. This is probably because occlusion between natural teeth results in greater displacement due to the presence of a periodontal membrane on both teeth. In addition, Koyama et al. reported no significant differences between the molar region on the implant side and on the contralateral side, even when clenching strength varied. Similarly, when clenching strength varied in this study, the occlusal contact area of the implant prosthesis did not increase than the contralateral tooth.

Comparison of proportion of occlusal contact area and occlusal load in all teeth accounted for by prosthetic implant and contralateral tooth

The proportion of occlusal force on the molar region of healthy dentition accounted for by the mandibular first molar on one side has previously been reported as 16 %. In the present study, however, the implant prosthesis accounted for a lower proportion of 9 % of the occlusal force on the molar region. No significant differences in occlusal load were observed between sides, but the proportion of occlusal load on all teeth borne by the implant prosthesis was less than that borne by the contralateral tooth. However, there was no significant difference in occlusal load between both molar regions. It suggested that occlusal loading on both molar regions have been balanced.

Future research

The present study examined implant prostheses immediately after setting, but the occlusal contact of implant prostheses is believed to change over time as a result of factors such as extrusion of opposing teeth, abrasion from neighboring surfaces, and tooth attrition. In the future, we intend to use the results of the present study to carry out a prospective study that will survey the period of 1 year from immediately after setting, which is when problems are most common. This future study will have a greater number of subjects and will evaluate parameters such as mastication function. This study will aim to clarify how the occlusal contact of the implant prosthesis changes within the dentition and to draw up guidelines on this basis.

The results suggest that the occlusal contact of implant prostheses can be evaluated from low to high clenching intensities using Blue Silicone and Dental Prescale. There was a trend for implant prostheses to be adjusted such that immediately after setting the occlusal contact area, the occlusal load of the implant superstructure was less than that of the contralateral tooth. This is likely to be due to dentists taking into account the small tissue displaceability of implants.

The occlusal load on implant prostheses in a single intermediary mandibular first molar deficit tended to increase less with clenching strength than the load on the contralateral tooth. In addition, the proportion of the occlusal load on the whole dentition accounted for by the implant prosthesis was less than the proportion accounted for by the contralateral tooth. However, there was no significant difference in occlusal load between both molar regions. It suggested that occlusal loading on both molar regions has been balanced. The adequate occlusion on implant prosthesis has not been clear. However, we will be able to obtain clinical suggestions for the occlusion that should be given to prosthetic implants through a longitudinal follow-up study.