title: Effect of polyvinylsiloxane material and impression handling on the accuracy of digital models.
abstract: BACKGROUND
  The objective of this study was to evaluate the accuracy and reliability of measurements on digital models obtained by scanning impressions 5, 10, and 15 days after they were made from 2 soft putty polyvinylsiloxane (PVS) materials.
  
  
  METHODS
  Thirty volunteers were selected for making impressions of their dentitions with alginate to create a plaster model and with PVS impression material to create a digital model by laser scanning. Three examiners made the plaster model measurements with digital calipers and repeated these measurements on the digital models made from the scanned PVS impressions. A total of 34 distances were evaluated. Paired t tests were used to evaluate intraexaminer error and the accuracy of the digital model measurements. Measurement reproducibility and reliability among examiners were tested.
  
  
  RESULTS
  Although statistically significant differences between measurements on plaster and digital models were found, these discrepancies were not clinically significant except for overbite. Both plaster and digital models had high intraclass correlation coefficient values.
  
  
  CONCLUSIONS
  Digital models acquired by laser scanning of 2 types of soft putty PVS material may be used with clinically acceptable accuracy, reliability, and reproducibility, even at a postscanning interval of 15 days.
authors.affiliation: Postgraduate student, Department of Orthodontics, School of Dentistry, Federal Fluminense University, Niterói, Rio de Janeiro, Brazil. Electronic address: leocamardella@globo.com.
authors.forename: Leonardo Tavares
authors.initials: LT
authors.lastname: Camardella
authors.affiliation: Postgraduate student, Department of Orthodontics, School of Dentistry, Federal Fluminense University, Niterói, Rio de Janeiro, Brazil.
authors.forename: David Silveira
authors.initials: DS
authors.lastname: Alencar
authors.affiliation: Assistant professor, Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Hero
authors.initials: H
authors.lastname: Breuning
authors.affiliation: Professor, Department of Orthodontics, School of Dentistry, Federal Fluminense University, Niterói, Rio de Janeiro, Brazil.
authors.forename: Oswaldo
authors.initials: O
authors.lastname: de Vasconcellos Vilella
mesh_terms: D002133:Calcium Sulfate; D003198:Computer Simulation; D003760:Dental Impression Materials; D011145:Polyvinyls; D015203:Reproducibility of Results; D012833:Siloxanes
chemical_list: D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane; D002133:Calcium Sulfate