ABSTRACT
<p><b>OBJECTIVE</b>Osseointegration of orthodontic microscrew implant is influenced by tooth extraction. This study aims to evaluate the safety margin of the osseointegration of orthodontic implants by investigating the healing process of the implant-bone interface through histopathological studies and quantitative determination.</p><p><b>METHODS</b>Twelve male beagles were selected and randomly divided into four groups. An orthodontic microscrew was implanted beside the tooth extraction area. Animals were killed in 1, 3, 8, and, 12 weeks to investigate tissue response. Histomorphological observation and bone implant contact ratio (BIC) tests were performed at different healing time after implantation.</p><p><b>RESULTS</b>A new bone was formed on the implant-bone interface of the control group. Bone resorptions were also detected in the experimental group 3 weeks after implantation. The BIC level of the control groups increased during the first 8 weeks; no change was observed anymore after the 8th week. On the other hand, the BIC value in the experimental group decreased in the first 3 weeks. It then increased rapidly and reached its peak of 80.08% in the 8th week. No significant difference wa s found between the experimental and control groups in the first 3 weeks. After the 3rd week, the BIC value of the experimental group (44.35%) was lower than that of the control group (55.46%) (P < 0.01).</p><p><b>CONCLUSION</b>The healing process after implantation was influenced by tooth extraction. Bone resorption was detected at an early stage. However, vigorous bone remodeling was observed subsequently.</p>