Investigation of the contact between dental root and miniscrew during orthodontic tooth movement—an animal study

• Main Authors: Cheng-Tsung Huang, 黃丞聰
• Other Authors: Chung-Chen Yao
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/51831592482079303813

碩士 === 國立臺灣大學 === 臨床牙醫學研究所 === 96 === Skeletal anchorage plays an important role in contemporary orthodontics. Miniscrew, which is one of the most frequently used temporal anchorage device (TADs), is famous for its small size, versatile usage, low price, and ease of insertion and removal. However, there are risks of root damage if we move a teeth to contact a miniscrew being inserted between two roots. Therefore, we used histological analysis on experimental animals to realize the possible response of root and surrounding tissues during this traumatic incidence. In dog A , both upper and lower arch first and second premolar were extracted. Miniscrew were placed over distal side of canine and mesial side of third premolar (without contacting miniscrews). Three weeks later, space between canine and third premolar was attempted to close with 150g NiTi coil spring. After fifteen weeks, active force was stopped and fixation was performed to reserve the relation between dental root and miniscrew. In dog B, force application was continued until experiment completed. Newly formed calcifying tissues were labeled with bone markers, and the experimental animals were sacrificed after 24 weeks. In order to observe the bone labeling markers and cell morphology surrounding miniscrews and tissues, samples were embedded with resin and sectioned with microtomes. Experimental findings:（1）There were fibroblasts, collagen fibers and capillaries surrounding the screws and roots. Inflammatory cells and cementoclasts were not found on the damaged root surface.（2） Long and shallow defect areas were seen on root surface if dental root was indeed in contact with the miniscrew. However, irregular resorptive concavity also could be detected as orthodontically induced root resorption.（3）Root repair was not initiated over resorptive area if dental root and miniscrew were still in contact with each other. On the contrary, reparative cementum can be found over resorbed concavity if dental root was displaced away from miniscrew surface.