Objective      To provide the evidence for the clinical application of micro-screws by studying the effect of bone structure reconstruction after tooth extraction on the stability of its adjacent micro-screws as an implanted anchorage.     Methods      Eight male Beagle dogs were randomly divided into 4 groups according to the different healing periods of time（1

3

8

and 12 weeks）after tooth extraction. The third and fourth canine teeth (P3 and P4) were extracted from each dog. A total of 128 micro-screws were implanted into the adjacent areas of P3

P4

P2

and the first motor tooth (M1) after extraction. The maximal pull-out force (POF) value for 96 tissue masses of micro-screws was tested and analyzed.     Results      No significant difference in the POF value was found between the experimental and control groups during the first week after tooth extraction (P0.05). The POF value was significantly lower in control group than in experimental group during the third week after tooth extraction (P0.05). The POF value reached its peak in both groups at week 8. The POF value increased with the prolonged time in the first 8 weeks and began to decrease from week 12. A significant difference in POF value was observed in experimental group at different periods of time and in control group between week 12 and weeks 3 and 8 (P0.05).     Conclusion     Implanted micro-screws adjacent to the extraction wounds can maintain the anchorage stability during the non-load healing period. The early healing of extraction wounds may exacerbate inflammatory reactions on the interface between implanted micro-screws and bone

and promote the bone absorption efficacy

thus increasing the immediate loading risk.