Accuracy of the infrazygomatic orthodontic bone screws digital planning and surgical guided positioning: A observational study

Objectives: The objective of the study was to evaluate the accuracy of surgical guidance for the insertion of infrazygomatic (IFZ) miniscrews by means of a cone beam computed tomography (CBCT) evaluation. Material and Methods: Nine patients (five men and four women, from 14.8 to 41.4 years of age) were recruited for the study. Rhinoceros software was used to digitally plan the infrazygomatic miniscrew insertion with the INFRABSTEER method (INFRA-zygomatic and Buccal Shelf method), superimposing intraoral scans and a CBCT obtained at T0. No orthodontic movement was performed, and six months later a second CBCT was done (T1). Rhinoceros software was used to superimpose T0 and T1 files. Mesio-distal, bucco-palatal, and vertical linear discrepancy in cap and tip and an angular discrepancy between the mini-screws was measured. To check the repeatability of the measurements, the intraclass coefficient (ICC) was calculated. The significance level considered is P < 0.05. The ICCs are all >0.85 and significantly different from 0 (P < 0.05), indicating excellent repeatability of measurements. Results: The lowest mean linear distance was found to be the mesio-distal distance at the tip with 0.23 ± 0.241 mm. All linear distances produced an average distance of less than 0.5 mm, except for the bucco-palatal distance measured at the tip. The smallest angular measurement was obtained from the intersection of the axes of the miniscrews in the mesio-distal plane (1.58° ± 1.458°). Conclusion: The combination of a digitally planned and a template-guided surgical positioning procedure allows excellent control of infrazygomatic miniscrews insertion.