Abstract
Microscrew can provide stable and efficient anchorage control and require minimal compliance,which led to the expansion of MIA technology. Objectives: The purpose of this study was to evaluate the effects of the healing time on the stability of the micscrews under 100g orthodontic loading. Methods: Thirty-six microscrews were inserted into the maxillary jaws of 6 beagles. The screws were divided into 3 groups through the healing time: the immediately loading group,the 2-week healing time group and the 4-week healing time group. A force of 100 g was applied using nickel-titanium coil springs. Eight weeks after loading, the screws with the surrounding bone were prepared for osseointegration evaluation.Results: osseointegration and fibrous tissue were found in the interface between micro-screw and osseous tissue.The osseointegration was different among the three different healing time groups(p<0.01).The bone microscrew contact ration(BIC) in immediately loading group was 43.7%,in 2-week healing time group was 66.3% and in 4-week healing time group was 73.3%..Conclusion:healing time is the very important fator to the microscrew's stability.