title: Implant angulation: a measurement technique, implant overdenture maintenance, and the influence of surgical experience.
abstract: OBJECTIVE
  The purposes of this study were to develop a technique to measure the angulation between two implants and between each implant and reference planes, to analyze the relationship between the maintenance (adjustments and repairs) of ball-attachment mandibular implant overdentures and implant angulation, and to see if there is any correlation between surgeon experience and implant orientation.
  
  
  METHODS
  Final casts of 41 patients who had received two-implant ball-attachment mandibular overdentures were used to measure implant angulations using digital photographs and plane geometry. The measured angles were compared with the number of adjustments and repairs of the prostheses and analyzed by surgeon experience for any trends.
  
  
  RESULTS
  No significant relationships were found between number of adjustments and repairs and the interimplant angles. However, there was a significantly higher number of repairs when the lingual inclination of an implant was > or = 6.0 degrees (P = .033) or if the facial inclination was < 6.5 degrees (P = .036). Less experienced surgeons had a significantly greater tendency to place implants that diverged from each other in the frontal plane (P = .045) and with a facial or lingual inclination in the sagittal plane (P = .035).
  
  
  CONCLUSIONS
  While interimplant angulation did not appear to affect prosthesis maintenance, individual implants with a lingual inclination > or = 6 degrees and a facial inclination < 6.5 degrees were associated with significantly more prosthesis repairs. There was a tendency for implants placed by less experienced surgeons to demonstrate greater inclination.
authors.affiliation: Department of Oral Health Sciences, University of British Colombia, 2199 Wesbrook Mall, Vancouver, British Colombia, Canada, V6T 1Z3. jnwalton@interchange.ubc.ca
authors.forename: J N
authors.initials: JN
authors.lastname: Walton
authors.forename: S C
authors.initials: SC
authors.lastname: Huizinga
authors.forename: C C
authors.initials: CC
authors.lastname: Peck
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002508:Cephalometry; D002983:Clinical Competence; D000044:Dental Abutments; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003779:Denture Design; D003780:Denture Repair; D003781:Denture Retention; D003828:Denture, Overlay; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000601:surgery; D008433:Mathematics; D008875:Middle Aged; D023861:Photography, Dental; D015203:Reproducibility of Results; D013223:Statistics as Topic; D013499:Surface Properties; D013515:Surgery, Oral
chemical_list: D015921:Dental Implants