title: The precision of fit at the implant prosthodontic interface.
abstract: BACKGROUND
  Percussion, visual observation, and conventional periapical radiographs are the methods most frequently used clinically to evaluate the accuracy of implant component assemblies, whereas methods to measure the precision of fit are limited.
  
  
  OBJECTIVE
  In this study the Periotest instrument was used to evaluate the stability of the interfaces between the implant and the abutment, along with the abutment and the gold cylinder under a series of assembly conditions. The hypothesis tested is that a more negative Periotest value (PTV) would indicate an accurate fit and a more positive value PTV would correlate with an inaccurate fit.
  
  
  METHODS
  To investigate this hypothesis in vitro, two bovine ribs were used as patient simulation models. Each model contained three self-tapping Brånemark implants placed approximately 7 to 10 mm apart and arranged in a reasonable curvature. A series of component assembly conditions were created as accurate and inaccurate with thickness gauges of 25.4 microns, 50.8 microns, and 101.6 microns.
  
  
  RESULTS
  The mean Periotest values and SDs for accurately assembled abutments and gold cylinders were -6.0 +/- 0.32 and -3.4 +/- 0.68, respectively. Periotest value data of the assembly conditions were statistically analyzed with multiple regression analysis. The misfit in the implant to abutment interface resulted in a more negative Periotest value trend (r = 0.54) with increases in gauge thickness. However, the same magnitudes of misfit at the abutment to gold cylinder interface produced a more positive Periotest value trend (r = 0.72).
  
  
  CONCLUSIONS
  The PTV trends were consistent with increased stability at the abutment to implant interface from the increasing magnitude of misfit created with the thickness gauges. In contrast, the measurement trends observed for the abutment to gold cylinder interface were consistent with decreased stability with each increase in gauge thickness inserted at the interface.
authors.affiliation: Department of Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, USA.
authors.forename: K B
authors.initials: KB
authors.lastname: May
authors.forename: M J
authors.initials: MJ
authors.lastname: Edge
authors.forename: M M
authors.initials: MM
authors.lastname: Russell
authors.forename: M E
authors.initials: ME
authors.lastname: Razzoog
authors.forename: B R
authors.initials: BR
authors.lastname: Lang
mesh_terms: D000054:Acceleration; D000818:Animals; D002417:Cattle; D000044:Dental Abutments; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported; D005069:Evaluation Studies as Topic; D006047:Gold Alloys / Q000737:chemistry; D010474:Percussion; D011861:Radiography, Dental; D012044:Regression Analysis; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D015921:Dental Implants; D006047:Gold Alloys