title: Three-dimensional bone microstructures of the mandibular angle using micro-CT and finite element analysis: relationship between partially impacted mandibular third molars and angle fractures.
abstract: The mandibular angle is one of the areas of the mandible that are prone to bone fractures, and the presence of an impacted third molar has been found to be associated with increased risk of angle fractures. The factors involved in bone fractures are the amount and direction of load, and the biomechanical and anatomical properties of bone. In the present study, micro-focused X-ray computed tomography was performed to observe and analyze the three-dimensional (3D) bone microstructure of the mandibular angle, and finite element analysis was conducted to examine the relationship between angle fractures and the presence or absence of mandibular third molars. 3D bone microstructure showed no marked difference between mandibles with and without third molars. Finite element analysis showed that, in the mandible with a third molar, stress was concentrated around the root apex of the third molar, and was transmitted in a direction matching the clinical findings of angle fractures. The results obtained in this study suggest that the presence of an impacted third molar changes the concentration and transmission of stress in the mandible, thus increasing the risk of an angle fracture.
authors.affiliation: Department of Anatomy, Tokyo Dental College, Chiba, Japan. takada-h@mug.biglobe.ne.jp
authors.forename: Hideki
authors.initials: H
authors.lastname: Takada
authors.forename: Shinichi
authors.initials: S
authors.lastname: Abe
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tamatsu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mitarashi
authors.forename: Hideki
authors.initials: H
authors.lastname: Saka
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Ide
mesh_terms: D016880:Anisotropy; D015519:Bone Density; D002102:Cadaver; D003799:Dental Stress Analysis / Q000379:methods; D020342:Finite Element Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology; D008337:Mandibular Fractures / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D008964:Molar, Third / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D014095:Tooth, Impacted / Q000150:complications*