Root Contact during Drilling for Microimplant Placement Affect of Surgery Site and Operator Expertise

Objective: To determine the surgery site dependency of root contact during drilling for orthodontic microimplant placement and to analyze the influence of clinicians' expertise on the results. Materials and Methods: Dental arches with resin teeth were mounted on a dental phantom (P-5/3 TS, Frasaco, Germany). Drilling was conducted in six locations frequently selected for microimplant placement: between the central incisors, between the maxillary first molar and second premolar, and between the mandibular first and second molars, bilaterally. The 28 qualified dentists who participated were divided into two groups based on their clinical experience. A total of 192 drillings were performed by the experienced group and 240 by the inexperienced group. The damaged root surfaces were classified as "moderate" or "severe." Results: Significant differences in both overall and site-dependent rates of root contacts were found between the groups. Overall rates for the experienced and inexperienced groups were 13.5% and 21.3%, respectively. For the experienced group, the incidents occurred predominantly in the lower left (34.4%) and upper right (18.8%) posterior regions. The most susceptible teeth were numbers 36 and 16. In contrast, for the inexperienced group, all four posterior regions were susceptible. Conclusions: The surgery site and clinicians' expertise had significant effects on the rate as well as the pattern of root contacts. (Angle Orthod 2010;80:130-136.)