Thickness of Buccal Bone at Various Sites of the Mandible and Its Clinical Significance in Monocortical Screws Placement Using Multi-Slice Computed Tomography

Abstract

Background:Open reduction and internal fixation (ORIF) of using miniplates and screws is the treatment of choice ofmandibular fractures. It is important to know both: the region where the bone provides a firm anchorage, and thetopography of the dental apices and inferior alveolar nerve to avoided imaging them when inserting the screw. Theaim of this study is to determine the thickness of buccal cortical plate and that of buccal bone at the parasymphysisand mandibular body, thereby determining the area that provide a firm anchorage and the maximum length ofmono-cortical screws that can be safely placed in these regions without injuring the tooth roots or mandibular nerve.Materials and Methods: The sample of the present study was 110 Iraqi subjects (77 males & 33 females) aged (18-35)years old who admitted to Computed Tomography scan unit in AL-Sadr Teaching Hospital in Al-Najaf city to getComputed Tomographic examination of facial bones. The conventional sections of CT (axial, coronal) used to dothe measurements and dental planning analysis also used. The thickness of buccal cortical plate and the thickness ofbuccal bone were measured at the level of root apex of (canine, first premolar, second premolar) and at the levelofroot apex and inferior alveolar canal in mesial and distal root of first and second molar.Results: There was no statistical significant difference in buccal cortical plate and buccal bone thickness betweenage and gender at most measured sites. Using of 4mm screw is safe in distal root region of 2nd molar at the level ofapex and that of inferior alveolar canal for both males and females. Moving slightly forward in position to the mesialroot of 2nd molar 1mm will be lost from safety margin, while making only the 3mm screw is safe. For the remaininganterior positions only the minimum screw length of 2 mm is safe.Conclusions: Thickness of buccal cortical plate and buccal bone in various sites could be measured precisely usingMultislice Computed tomography which can guide surgeons in selecting the proper screw length without causinginjury to tooth apex or inferior alveolar nerve.