Abstract: PURPOSE: To investigate the effect of different occlusal contacts on occlusal balance index of single posterior dental implants, and to provide evidence for clinical improvement of occlusal balance of implant prostheses. METHODS: Twenty-four patients with single posterior teeth implants were selected from December 2018 to December 2019 in Dental and Ophthalmic Clinic of Putuo District. According to the occlusal contact degree between different prostheses and opposite teeth, all implants were randomly divided into two groups: a 12 μm occlusal paper was used to adjust the occlusal degree in group A, while a 20 μm occlusal paper was used in group B. The occlusal paper could be extracted from between the prosthesis and the opposite teeth when clenched. The occlusal force was measured at the intercuspal position(ICP), with T-scan Ⅲ system before and on the day of restoration as well as 3, 6, 12 and 18 months after restoration, and their occlusal balance index were calculated. The data were analyzed with SPSS 21.0 software package. RESULTS: The occlusal balance index of the two groups was(-0.389+0.066) and (-0.368+0.055) before the day of restoration respectively, while (-0.249+0.069) and (-0.283+0.056) respectively on the restoration day. There was no significant difference between group A and group B during these two periods. The occlusal balance index of these two groups was (-0.052+0.022) and (-0.169+0.063) respectively 3 months after restoration, (-0.025+0.015) and (-0.088+ 0.045) respectively 6 months after restoration, (-0.010+0.008) and (-0.029+0.016) respectively 12 months after restoration as well as (-0.000+0.000) and (-0.006+0.008) respectively 18 months after restoration. The absolute value of occlusal balance index in group A was much less than that in group B at the 3rd, 6th, 12th months after restoration. On the contrary, the increase extent of group A was much larger than that of group B. There was significant difference between the two groups (P<0.05). At 18 month after restoration, the occlusal balance index of the two groups were all close to "0" . CONCLUSIONS: Occlusal balance will be obtained gradually after the restoration of a single posterior tooth implant and earlier when a 12 μm occlusal paper was used to adjust the occlusal degree.

Key words: Single posterior tooth, Occlusal contact, Occlusal balance index