title: Bone stress analysis of various angulations of mesiodistal implants with splinted crowns in the posterior mandible: a three-dimensional finite element study.
abstract: OBJECTIVE
  Ideally, implants for dental prostheses should be placed parallel to each other. However, anatomic limitations sometimes make nonparallel implants necessary. The purpose of this study was to determine the bone stresses on implants tilted at various angles and to determine what arrangements might carry a higher risk of failure.
  
  
  METHODS
  Three-dimensional finite element models were constructed using the mean values measured for the Asian mandible in the first and second molar areas. Eight implants were divided into three tilting types: parallel implants (P1(PP), P2(MM), and P3(DD)), convergent implant apices (C1(PD) and C2(MP)), and divergent implant apices (D1(DP), D2(DM), and D3(PM)). A biting load of 200 N was applied vertically and obliquely on the occlusal central fossa of the splinted crowns. The main effects of each level of the three investigated factors (loading type, relationship of implant apices, and distal tilting of one or both implants) in terms of the stress values were computed for all models.
  
  
  RESULTS
  The loading type was the main factor affecting the stress in bone when comparing implant apices and distal tilting of the implant body. When loading was combined with distal tilting, the stress values were significantly increased, especially in models P3(DD) and C1(PD).
  
  
  CONCLUSIONS
  The loading type is the main factor affecting the stress distribution for different implantation arrangement. Moreover, placement of the implants with distal tilting should be avoided in the posterior mandible.
authors.affiliation: Department of Prosthodontics, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Taiwan.
authors.forename: Ting-Hsun
authors.initials: TH
authors.lastname: Lan
authors.forename: Chin-Yun
authors.initials: CY
authors.lastname: Pan
authors.forename: Huey-Er
authors.initials: HE
authors.lastname: Lee
authors.forename: Heng-Li
authors.initials: HL
authors.lastname: Huang
authors.forename: Chau-Hsiang
authors.initials: CH
authors.lastname: Wang
mesh_terms: D001696:Biomechanical Phenomena; D001732:Bite Force; D003198:Computer Simulation; D003442:Crowns; D003724:Dental Arch / Q000503:physiopathology; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D008334:Mandible / Q000503:physiopathology*; D008954:Models, Biological; D008963:Molar; D012307:Risk Factors; D013314:Stress, Mechanical
chemical_list: D015921:Dental Implants