title: Factorial analysis of variables affecting bone stress adjacent to the orthodontic anchorage mini-implant with finite element analysis.
abstract: BACKGROUND
  Mini-implants are now widely accepted as anchorage for orthodontic tooth movement because of the convenience of the placement procedure, their comparative low cost, and the fact that they can be immediately loaded after surgery. In this study, we incorporated a finite element approach and factorial analysis to determine the biomechanical effects of exposure length of the mini-implant, the insertion angle, and the direction of orthodontic force.
  
  
  METHODS
  Twenty-seven finite element models were constructed to simulate the biomechanical response of the alveolar bone adjacent to the mini-implant. Factorial analysis was performed to investigate the comparative influence of each factor.
  
  
  RESULTS
  The simulation results showed that the exposure length of the mini-implant had a statistically significant influence on bone stress, with a contribution of 82.35%. Increased exposure length resulted in higher bone stress adjacent to the mini-implant. Whereas all factors investigated had a statistically significant influence on cancellous bone stress, the stress values associated with cancellous bone were much less than those of cortical bone.
  
  
  CONCLUSIONS
  Increased exposure lengths resulted in higher bone stresses adjacent to the mini-implant. The percentage of contribution of the insertion angle of the mini-implant (6.03%) was also statistically significant but much less than that of the exposure length (82.35%). The direction of orthodontic force had no significant effect on cortical bone stress.
authors: Department of Biomedical Engineering, I-Shou University, Kaohsiung, Taiwan.
authors: Ting-Sheng
authors: TS
authors: Lin
authors: Feng-De
authors: FD
authors: Tsai
authors: Chih-Yu
authors: CY
authors: Chen
authors: Li-Wen
authors: LW
authors: Lin
mesh_terms: D000539:Alveolar Process / Q000502:physiology*; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D003758:Dental Implantation, Endosseous / Q000295:instrumentation / Q000379:methods*; D015921:Dental Implants; D003799:Dental Stress Analysis; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D006801:Humans; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation* / Q000379:methods
chemical_list: D015921:Dental Implants