Cone Beam Computed Tomography References for Placement Site and Insertion Angle of a Palatal Orthodontic Miniscrew in the Posterior Maxillary Area

Abstract

Background: To strengthen the safety and stability of palatal orthodontic miniscrew, the interradicular width, and the thickness of palatal mucosal and bone should be considered, providing a reference for placement site and insertion angle of palatal orthodontic miniscrew. Methods: The imaging data of 90 adult patients were selected for this study, and the jaw bone was reconstructed by scanning. On the maxillary palatal aspect, distances of 12, 14, 16 and 18 mm from the palatal apex of the first maxillary molar between the maxillary second premolar and first molar, and between the maxillary first and second molars were selected as measurement points. Linear measurements included the interradicular width of the palatal root between adjacent teeth, as well as the palatal mucosal thickness and bone thickness if the miniscrew was inserted at 30°, 45°, 60° and 90° relative to the long axis of the tooth. Data comparisons were performed via one-way analyses of variance and least significant difference tests.Results: The greater the insertion angle, the shorter the interradicular width and mucosal thickness, the difference among all these angles was statistically significant (P < 0.05)；an angle between 60–90° was safer for insertion. The higher the placement site, the greater the interradicular width and mucosal thickness, the difference among all placement sites was statistically significant (P < 0.05); placement sites between 14–16mm had greater interradicular widths.Conclusions: It is safer to insert a palatal orthodontic miniscrew at a 60–90° angle 14–16 mm away from the palatal apex of the first maxillary molar between the maxillary second premolar and first molar. Further, we found it is safer to insert a palatal orthodontic miniscrew at a 60° angle 14–16 mm away from the palatal apex of the first maxillary molar between the maxillary first and second molars.