title: [Influence of bone quality on the stress distribution for three-posterior immediately loaded implants: a three-dimensional finite element analysis].
abstract: OBJECTIVE
  To assess and compare the peri-implant stress distribution of three posterior implants under immediate loading with 4 different bone qualities using three dimensional (3D) finite element (FE) analysis.
  
  
  METHODS
  A 3D finite element model representing three implants in a portion of mandible at the 654 region was developed, and three implants received a crown each. Four types of bone qualities (B1, B2, B3 and B4) were designed for the model. Load of 100 N was applied on the occlusal surfaces of the crowns at a 45° angle to the vertical axis of the implants.
  
  
  RESULTS
  Von Mises stresses in the peri-implant bone of 4 in bone quality from B1 to B4 were (13.17 ± 9.32), (12.95 ± 9.14), (15.00 ± 9.44), and (16.81 ± 10.74) MPa, and those of 5 were (15.51 ± 10.32), (14.73 ± 8.96), (16.79 ± 8.40), and (18.34 ± 8.45) MPa. Stress in bone quality B4 showed the highest value, followed by B3 bone, the lowest stress were found in B1 and B2 bone. It was significantly different (P < 0.05). However, von Mises stresses in different quality of bone around 6 [(42.45 ± 25.71), (41.66 ± 25.29), (42.70 ± 23.24), (42.06 ± 23.66) MPa] were close to each other, and were as twice or three times as those of 4 and 5, irrespective of different bone qualities.
  
  
  CONCLUSIONS
  The stress distribution around implant under immediate loading was not only affected by different bone qualities, but also by the direction of loading, and the latter may have a greater impact when a severe load delivered.
authors: Department of Stomatology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China.
authors: Xia-yun
authors: XY
authors: Chen
authors: Song-ling
authors: SL
authors: Chen
authors: Mei-chao
authors: MC
authors: Zhang