title: Stress distribution and displacement by different bone-borne palatal expanders with micro-implants: a three-dimensional finite-element analysis.
abstract: The aim of this study was to analyze stress distribution and displacement of the maxilla and teeth according to different designs of bone-borne palatal expanders using micro-implants. A three-dimensional (3D) finite-element (FE) model of the craniofacial bones and maxillary teeth was obtained. Four designs of rapid maxillary expanders: one with micro-implants placed lateral to mid-palatal suture (type 1), the second at the palatal slope (type 2), the third as in type 1 with additional conventional Hyrax arms (type 3), and the fourth surgically assisted tooth-borne expander (type 4) were added to the FE models. Expanders were activated transversely for 0.25mm. Geometric nonlinear theory was applied to evaluate Von-Mises Stress distribution and displacement. All types exhibited downward displacement and demonstrated more horizontal movement in the posterior area. Type 3 showed the most transverse displacement. The rotational movement of dentoalveolar unit was larger in types 1 and 3, whereas it was relatively parallel in types 2 and 4. The stresses were concentrated around the micro-implants in types 1 and 3 only. Type 2 had the least stress concentrations around the anchorage and showed alveolar expansion without buccal inclination. It is recommended to apply temporary anchorage devices to the palatal slopes to support expanders for efficient treatment of maxillary transverse deficiency.
authors.affiliation: Graduate School, The Catholic University of Korea.
authors.forename: Hye Kyung
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Graduate School, The Catholic University of Korea.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bayome
authors.affiliation: Department of Orthodontics, Seoul St. Mary's Hospital, The Catholic University of Korea.
authors.forename: Chee Soo
authors.initials: CS
authors.lastname: Ahn
authors.affiliation: Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul, Korea.
authors.forename: Seong-Hun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Orthodontics, Center for Advanced Dental Education, Saint Louis University, MO, USA.
authors.forename: Ki Beom
authors.initials: KB
authors.lastname: Kim
authors.affiliation: Department of Orthodontics, Yeouido St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Sung-Seo
authors.initials: SS
authors.lastname: Mo
authors.affiliation: Department of Orthodontics, Seoul St. Mary's Hospital, The Catholic University of Korea, kook190036@yahoo.com.
authors.forename: Yoon-Ah
authors.initials: YA
authors.lastname: Kook
mesh_terms: D000539:Alveolar Process / Q000473:pathology; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D015921:Dental Implants; D005147:Facial Bones / Q000473:pathology; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007180:Incisor / Q000473:pathology; D008437:Maxilla / Q000601:surgery; D008904:Miniaturization; D008954:Models, Biological; D008963:Molar / Q000473:pathology; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D010159:Palate / Q000601:surgery; D012399:Rotation; D013314:Stress, Mechanical
chemical_list: D015921:Dental Implants