[Stability of the miniscrew implant during healing period].

Objective: To evaluate the stability of mini-screw implant during different healing periods in the unloaded conditions.

Methods: Sixty titanium mini-screws were used in this study. A total of 10 New Zealand white rabbits were randomly divided into 5 groups according to different healing periods. The stability was evaluated biomechanically at different time points. One-way ANOVA and correlation analyses were used.

Results: (1) After 4 weeks and 8 weeks of healing, maximal pull-out loads were (179.68 +/- 24.65) N and (212.06 +/- 42.51) N, respectively. The maximal torques were (0.47 +/- 0.13) N.m and (0.61 +/- 0.16) N.m, respectively. (2) Significant difference in maximal torque was found between 4 week and 8 week healing groups. (3) Both reverse torque and pull-out load significantly correlated with healing time.

Conclusions: Fourth-week is a critical time point in the progress of osseointegration. Within 8 weeks of healing process, the stability of implant was significantly correlated with healing time.