title: Influence of dentist experience with scan spray systems used in direct CAD/CAM impressions.
abstract: BACKGROUND
  Direct optical impression systems requiring powder opacification are widely used in prosthodontics, but little information is available about the influence of the dentist on the quality of scan sprays used for computer-aided design and computer-aided manufacturing (CAD/CAM) impressions.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the influence of operator experience on scan spray homogeneity and thickness on tooth surfaces before direct optical impressions are made.
  
  
  METHODS
  A total of 36 crown-prepared acrylic resin teeth were coated (Optispray) for direct optical impressions by 3 experienced dentists and 3 inexperienced dentists (n=18 teeth per group). The teeth were visually scored for coating homogeneity (1, heterogeneous; 2, average; 3, homogeneous). To determine the coating thickness (μm), the teeth were resin-embedded, cut, and polished. A stereomicroscope (×100 magnification) was used to examine 148 areas per tooth. The results were statistically analyzed with the nonparametric Spearman and Mann-Whitney tests (α=.05).
  
  
  RESULTS
  Coating homogeneity was significantly higher (P<.001) for the experienced group (92.41 ±6.65%) than for the inexperienced group (66.11 ±12.69%). Coatings were significantly thinner for the experienced group (43.1 ±14.09 μm) than for the inexperienced group (70.19 ±31.26 μm) for all crown areas (P=.007). Coatings were 52 μm thinner for occlusal areas (P<.001) for the experienced group than for the inexperienced group. Coatings were significantly thinner for buccal (P=.015) and lingual surfaces (P=.002) for the experienced group than for the inexperienced group. Coatings on cervical surfaces were significantly thinner for the experienced group (43.52 ±15.76 μm) than for the inexperienced group (63.45 ±29.93 μm) (P=.035).
  
  
  CONCLUSIONS
  Experienced dentists achieved greater homogeneity and thinner coatings on crown-preparation surfaces than inexperienced dentists.
authors.affiliation: Postgraduate student, Department of Prosthodontics, Faculty of Odontology, University of Lille Nord de France, Lille, France. Electronic address: marion.dehurtevent@univ-lille2.fr.
authors.forename: Marion
authors.initials: M
authors.lastname: Dehurtevent
authors.affiliation: Assistant Professor, Department of Restorative Dentistry, Faculty of Odontology, University of Lille Nord de France, Lille, France.
authors.forename: Lieven
authors.initials: L
authors.lastname: Robberecht
authors.affiliation: Associate Professor, Department of Prosthodontics and Director of the Laboratory of Biomaterials, Faculty of Odontology, University of Lille Nord de France, Lille, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Béhin
mesh_terms: D000336:Aerosols; D002983:Clinical Competence; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D017076:Computer-Aided Design; D003761:Dental Impression Technique; D003815:Dentists; D004311:Double-Blind Method; D006801:Humans; D013499:Surface Properties; D019237:Tooth Cervix / Q000033:anatomy & histology; D019228:Tooth Crown / Q000033:anatomy & histology; D019231:Tooth Preparation, Prosthodontic / Q000379:methods; D014093:Tooth, Artificial
chemical_list: D000336:Aerosols; D020099:Coated Materials, Biocompatible