title: Two dental implants designed for immediate loading: a finite element analysis.
abstract: OBJECTIVE
  The aim of this study was to evaluate by finite element analysis the influence of the design of 3 different dental implants on micromovements, cervical shearing stress intensity, and stress distribution after occlusal loading.
  
  
  METHODS
  The first investigated implant was a classical cylinder, the second was reinforced by 2 bicortical locking pins, and the third was an expanding dental implant. The parameters analyzed were the implant's geometry, the quality of the cancellous bone, and the orientation of occlusal loading.
  
  
  RESULTS
  It was found that initial stability of the locking pin implant was greater than the initial stability of the other investigated implant designs, regardless of the quality of cancellous bone and orientation of occlusal loading; in low-rigidity cancellous bone, under a horizontal load (500 N), decreasing displacement compared to those of the other investigated implants was 16 microm. The apical expansion and locking pin implants exhibited favorable behavior regarding the distribution and intensity of cervical shearing stresses; in low-rigidity cancellous bone, under horizontal load, decreasing cervical stresses compared with those of the cylindric implant were 10 MPa for the apical expansion implant and 150 MPa for the locking pin implant.
  
  
  CONCLUSIONS
  For the cylindric implant, stresses were concentrated in the neck region; for the apical expansion implant, stresses were evenly distributed from the neck to the apex of the implant. For the locking pin implant, stresses around the neck were moderate and appeared concentrated around the pins.
  
  
  CONCLUSIONS
  Initial stability of the pin implant was greater than that of the expanding implant, but the expanding implant showed the most favorable stress distribution.
authors.affiliation: Faculty of Dental Surgery, Montrouge, University of Paris V, France. laurent.pierrisnard@wanadoo.fr
authors.forename: Laurent
authors.initials: L
authors.lastname: Pierrisnard
authors.forename: Guy
authors.initials: G
authors.lastname: Hure
authors.forename: Michel
authors.initials: M
authors.lastname: Barquins
authors.forename: Daniel
authors.initials: D
authors.lastname: Chappard
mesh_terms: D001732:Bite Force; D015519:Bone Density / Q000502:physiology; D001842:Bone and Bones / Q000033:anatomy & histology / Q000502:physiology; D003198:Computer Simulation; D000044:Dental Abutments; D015921:Dental Implants; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D008954:Models, Biological; D009068:Movement; D016012:Poisson Distribution; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium; D016474:Weight-Bearing
chemical_list: D015921:Dental Implants; D014025:Titanium