title: Effects of root morphology on stress distribution at the root apex.
abstract: It is thought that the stress concentration at the root apex caused by orthodontic force induces root resorption. The purpose of this study was to investigate stress distribution at the root in cases of deviated root shapes using finite element models (FEMs). To clarify this, five three-dimensional FEMs divided by deviated root shape (normal, short, blunt, bent root apex, pipette shape) were constructed and, experimental orthodontic forces, applied in a vertical (intrusive) and horizontal (lingual) direction to the tooth axis. In the short-root model, significant stress was concentrated at the middle of the root. The blunt-shaped root model showed no significant stress concentration at the root. In the models with a bent or pipette-shaped root, significant stress was concentrated at the root apex. During orthodontic force application, stress concentration was observed in the root of the models with short, bent, and pipette-shaped roots, indicating that attention must be paid to root shape during orthodontic treatment.
authors.affiliation: Department of Orthodontics, Nihon University School of Dentistry, Tokyo 101-8310, Japan. ohyama-k@dent.nihon-u.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Oyama
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Motoyoshi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hirabayashi
authors.forename: Kohei
authors.initials: K
authors.lastname: Hosoi
authors.forename: Noriyoshi
authors.initials: N
authors.lastname: Shimizu
mesh_terms: D000539:Alveolar Process / Q000502:physiology*; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D006801:Humans; D007180:Incisor; D009970:Orthodontics / Q000379:methods; D010486:Periapical Tissue / Q000502:physiology; D012391:Root Resorption / Q000209:etiology*; D013314:Stress, Mechanical; D019227:Tooth Apex / Q000033:anatomy & histology* / Q000502:physiology; D014087:Tooth Movement Techniques / Q000009:adverse effects*