A three-dimensional positioning guide for accurate mini-screw insertion Design and clinical application

doi:10.3969/j.issn.1673-8225.2009.13.043

Abstract：BACKGROUND: Mini-screw anchorage is an innovation technique applied in the orthodontic field, expanding the treatment ability of orthodontic appliance. Accurate of mini-screw insertion in the target position is a clinical problem which making orthodontist trouble in this technique application. OBJECTIVE: To introduce a kind of three dimensional guide of mini-screw used as anchorage in orthodontic treatment and to evaluate the positioning accuracy. DESIGN, TIME AND SE'I-rlNG: A contrast study was performed at the Department of Orthodontics, Capital Medical University from April to October 2005. PARTICIPANTS: Twenty cases (40 mini-screws) of maxillary critical anchorage requisition were considered as the experimental group, and 15 cases (30 mini-screws) who were not treated with surgical guide were considered as the control group. METHODS: Self-made stent was used as a positioning guide for implantation of mini-screw anchorage between the roots of upper second bicuspid and first molar. Thereafter, the position was measured. MAIN OUTCOME MEASURES: The vertical distance from measure points to the reference middle line were measured. RESULTS: In 40 mini-screws inserted with the aid of surgical guide, the average survival time of mini-screw as anchorage was 10.3 months, 2 were lost, and the success rate was 95%. The average survival time of 30 mini-screws in the control group was 9 months, 9 were loss, and the success rate was 70%. The positioning measurement showed that deviation of mini-screw was not found in the experimental group, but it was found in the control group. CONCLUSION: By aid of surgical guide splint, mini-scraw can be inserted correctly into the target region.