title: Comparability of clinical wear measurements by optical 3D laser scanning in two different centers.
abstract: OBJECTIVE
  The purpose of this study was to compare the use of different variables to measure the clinical wear of two denture tooth materials in two analysis centers.
  
  
  METHODS
  Twelve edentulous patients were provided with full dentures. Two different denture tooth materials (experimental material and control) were placed randomly in accordance with the split-mouth design. For wear measurements, impressions were made after an adjustment phase of 1-2 weeks and after 6, 12, 18, and 24 months. The occlusal wear of the posterior denture teeth of 11 subjects was assessed in two study centers by use of plaster replicas and 3D laser-scanning methods. In both centers sequential scans of the occlusal surfaces were digitized and superimposed. Wear was described by use of four different variables. Statistical analysis was performed after log-transformation of the wear data by use of the Pearson and Lin correlation and by use of a mixed linear model.
  
  
  RESULTS
  Mean occlusal vertical wear of the denture teeth after 24 months was between 120μm and 212μm, depending on wear variable and material. For three of the four variables, wear of the experimental material was statistically significantly less than that of the control. Comparison of the two study centers, however, revealed correlation of the wear variables was only moderate whereas strong correlation was observed among the different wear variables evaluated by each center.
  
  
  CONCLUSIONS
  Moderate correlation was observed for clinical wear measurements by optical 3D laser scanning in two different study centers. For the two denture tooth materials, wear measurements limited to the attrition zones led to the same qualitative assessment.
authors.affiliation: Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany. Electronic address: thomas_stober@med.uni-heidelberg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stober
authors.affiliation: Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: Navina
authors.initials: N
authors.lastname: Heuschmid
authors.affiliation: Preclinical Research, R&D, Ivoclar Vivadent, Schaan, Liechtenstein.
authors.forename: Gaby
authors.initials: G
authors.lastname: Zellweger
authors.affiliation: Statistical Unit, Institute for Social and Preventive Medicine, University of Lausanne, Switzerland.
authors.forename: Valentin
authors.initials: V
authors.lastname: Rousson
authors.affiliation: Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Rues
authors.affiliation: Preclinical Research, R&D, Ivoclar Vivadent, Schaan, Liechtenstein.
authors.forename: Siegward D
authors.initials: SD
authors.lastname: Heintze
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003761:Dental Impression Technique; D019554:Dental Restoration Wear; D003824:Denture, Complete; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged
keywords: Clinical wear; Denture teeth; In vivo wear; Laser scanning; Wear