In-vitro comparison of different palatal sites for orthodontic miniscrew insertion: Effect of bone quality and quantity on primary stability

• Published in: American journal of orthodontics and dentofacial orthopedics Vol. 154; no. 6; pp. 809 - 819
• Main Authors: Bourassa, Carine, Hosein, Yara K., Pollmann, Steven I., Galil, Khadry, Bohay, Richard N., Holdsworth, David W., Tassi, Ali
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-12-2018
• Subjects: Bone Density; Bone Screws; Cadaver; Dentistry; Humans; In Vitro Techniques; Orthodontic Anchorage Procedures - methods; Palate, Hard - diagnostic imaging; Palate, Hard - surgery; Torque; X-Ray Microtomography
• ISSN: 0889-5406; 1097-6752
• DOI: 10.1016/j.ajodo.2018.02.010

This experiment was undertaken to assess the primary stability of orthodontic miniscrews inserted at different sites in human cadaveric palatal bone for temporary skeletal anchorage, and to determine the effect of bone quality and quantity on their primary stability using microcomputed tomography imaging.
A total of 10 cadaveric maxillary hard palates were used for insertion of 130 orthodontic miniscrews (VectorTAS; Ormco, Orange, Calif; length, 6 mm; diameter, 1.4 mm). Upon insertion, maximal insertion torque (IT) was recorded. Imaging (microcomputed tomography) was performed before and after insertion for assessment of bone quality and quantity parameters (bone mineral density [BMD], bone thickness [BT], and length of screw engagement [LSE]). Differences in each parameter were assessed at the various insertion sites. Correlations between IT and measurements of BMD, BT, and LSE were evaluated.
Significant differences (P < 0.001) were found among insertion sites for IT, BT, and LSE, but not for BMD (P = 0.004). Correlations were found between IT and BMD (rs = 0.42; P < 0.001), IT and BT (rs = 0.58; P < 0.001), and IT and LSE (rs = 0.58; P < 0.001). Most perforations of miniscrews into the nasal cavity occurred posterior to the permanent second premolars.
The primary stability of orthodontic miniscrews in the palate is affected by bone quality and quantity, with higher primary stability obtained anterior to the second premolars and parasagittally at the level of the permanent first molars.
•Primary stability of orthodontic miniscrews depends on hard palate insertion site.•Primary stability was highest parasagitally and anterior to second premolars.•Primary stability was moderately affected by both bone quality and quantity.•An increased risk of nasal cavity perforation was found posterior to second premolars.