Estimating Angle Fractures Associated With Mandibular Third Molar Removal By Orthopantomography

Objective To access the possibility of angle fractures after the removal ofmandibular third molar with the use of orthopantomography (OPG).Method Randomly chose186pieces of OPG （including347mandibular thirdmolars）from June2009to June2010in the center of stomatology of Tongji Hospitalaffiliated to Hua Zhong Universtiy of Science and Technology. The total mandibularheight (a) and the residuary mandibular bone height (b) were measured on every OPG,and the value of b/a was obtained for further analysis. Also, the values of b/a of6cases with mandibular fracture after third molar removal were gained.Result The values of b/a of347mandibular third molars obey the Gaussiandistribution, and2of them were less than0.3(0.58%). The values of b/a of6caseswith mandibular fracture after the removal of third molar were also less than0.3.Conclusion The value of b/a less than0.3point to a higher risk of angle fractures,which might imply an effective way to access the possibility of angle fractures afterthe removal of mandibular3M with the analysis of OPG.