Evaluation of bone thickness of the infrazygomatic crest region and application sites and angles of miniscrews to be applied to this region on computed tomography in adults with completed maxillary sinus development

Aim: The aim of this study is to evaluate the infrazygomatic crest thickness on the maxillary 1st molar tooth and the placement of the miniscrews to be applied to this area at different angles and depths relative to the occlusal plane without damaging the mesiobuccal anda distobuccal roots of the 1st molar tooth by computed tomography. Material and Method: Computed tomography records of 30 female and 30 male adult patients with completed maxillary sinus development were examined in the Department of Radiology, Faculty of Dentistry, İnönü University. The hard tissues were arranged in coronal, axial and sagittal sections simultaneously on tomography. Occlusal plane was set as first reference line. This plane is expressed as the assumed plane where the right and left maxillary 1st molar teeth pass through the mesiobuccal cusps. For the 2nd reference line, separate lines were drawn to the mesiobuccal and distobuccal roots of the maxillary 1st molar tooth. The junction point of these tangent lines with the maxillary sinus floor was expressed as the S point. 8 lines were drawn from the determined S point to the occlusal plane, increasing by 5 degrees between 40⁰ and 75⁰. The 8 lines drawn reflected the appropriate miniscrew location and angle. Names from B1 to B8 were given to the points at the junction of the lines drawn from the S point with the lateral surface of the infrazygomatic crest. The lengths of the lines drawn from S point to B1-B8 points showed the thickness of the infrazygomatic crest. Lines perpendicular to the occlusal plane were drawn from B1-B8. These showed the appropriate insertion depths of the miniscrews relative to the occlusal plane. Each measurement was made as right and left region. The differences were compared. Results: In male individuals, the infrazygomatic bone thicknesses were found to be 3.79 ± 0.99 mm and 7.41 ± 2.68 mm between 40° and 75° the measurements according to the occlusal plane over the mesiobuccal root of the maxillary 1st molar, while their distance from the occlusal plane between the B1-B8 points is 20.78 ± 3.21 mm and 16.13 ± 5.10 mm. In the same measurements made on the distobuccal root, infrazygomatic bone thickness was found between 3.83 ± 1.31 mm and 8.09 ± 3.25 mm, while the distance of the points in the B1-B8 interval to the occlusal plane was found between 18.95 ± 3.28 mm and 13.53 ± 4.42 mm. In females, the infrazygomatic bone thicknesses were found to be 3.67 ± 1.17 mm and 6.99 ± 3.29 mm between 40° and 75° the measurements according to the occlusal plane over the mesiobuccal root of the maxillary 1st molar, while the distance from the occlusal plane between the B1-B8 points is 20.14 ± 2.55 mm. and 12.73 ± 3.81 mm. In the same measurements made on the distobuccal root, infrazygomatic bone thickness was found between 3.79 ± 1.32 mm and 8.51 ± 3.21 mm, while the distance of the points in the B1-B8 interval to the occlusal plane was found to be between 18.48 ± 2.14 mm and 12.73 ± 3.81 mm. Conclusion: No statistically significant difference was found between male and female individuals in all measurements performed in our study. There was no statistically significant difference in the right and left measurements made between male and female individuals. In the measurements made between 40 ° and 75 ° in male and female individuals, the distance of the points in the B1-B8 interval to the occlusal plane was found to be statistically greater in the mesiobuccal root of the maxillary 1st Molar compared to the distobuccal root. Key Words: Cone Beam Computed tomography, Infrazygomatic Crest, Miniscrew