[Clinical research on posterior single-implant occlusal contact time and force changes]

Objective: To investigate the changes of occlusal delay time, percentage of occlusal force and patients' subjective satisfaction of masticatory function for single implant crown in one year after the application of space reserved occlusion design. To provide data support and suggestions for clinical occlusion design. Methods: Patients who had received single posterior dental implant restoration in Department of Prosthodontics, Capital Medical University School of Stomatology from January 2019 to December 2019 were selected. At 0.5, 3, 6 and 12 months after restoration, the T-scan Ⅲ occlusal analyzer was used to detect and record the initial occlusal contact time of the natural tooth and implanted single crown, the occlusal force percentage of single implant prosthesis and corresponding tooth on the contralateral side (control teeth) on the contralateral side (control teeth) were also recorded. Subjective satisfaction with the masticatory function of the implants was recorded using visual analogue scale (VAS). The changes of occlusal delay time (the difference of the initial occlusal time between implant restoration and the natural teeth), percentage of occlusal force and patients' subjective feeling with time were analyzed. All data were analyzed by repeated measurement analysis of variance, bilatteral P<0.01 was considered statistically significant. Results: A total of 48 patients aged (36.8±8.4) years (23 males, 25 females, aged 23-50 years) were recruited. The occlusal delay time at 0.5 months was 0.15 (0.08, 0.20) s, at 3 months was 0.11 (0.06, 0.16) s, at 6 months was 0.07 (0.03, 0.13) s and at 12 months was 0.06 (0.03, 0.10) s. The occlusal delay time was shortened at every two time points, and the occlusal force percentage of the implant crown increased significantly. The percentage of occlusal force of implant prosthesis at 0.5 months was (7.7±4.8)%, at 3 months was (10.6±5.9)%, at 6 months was (12.3±6.2)% and at 12 months was (13.2±6.7)%. The most significant change was during the period of 0.5-3 months. At 0.5 months, the occlusal force of implant prosthesis was significantly lower than that of control teeth (14.3±6.5)% (P<0.01). The VAS score at 0.5 months was (7.06±1.64) and was (8.71±0.74) at 12 months. The score was increased and the difference was statistically significant from 3 month to 12 month (P<0.01). Conclusions: The change of occlusal force percentage of single posterior dental implant is most obvious within 3 months after restoration. The occlusal condition should be reexamined and adjust occlusal after 3 months of implant restoration as appropriate.