title: In vitro evaluation of the "replica technique" in the measurement of the fit of Procera crowns.
abstract: OBJECTIVE
  The objective of this study was to compare the film thickness of a light body polyvinylsiloxane addition silicone impression material using the "replica technique" (RT) to the film thickness resulting from the cementation of Procera copings.
  
  
  METHODS
  Twenty Procera copings were fabricated on ten casts each having one central incisor and one premolar. The thickness of the light body was first measured using the RT; then on the same casts dies were cemented with glass-ionomer cement, sawed, and the film thickness of cement was measured. These two materials were expected to behave differently under stress according to their respective physical properties.
  
  
  RESULTS
  The thickness of silicone material did not differ significantly from that of the glass-ionomer cement used in this experiment. Also, when the two groups of central incisors and premolars were taken separately, at three different areas (occlusal, axial, and cervical), no significant difference was found. Only when each surface (buccal, palatal, mesial, and distal) was compared separately at the cervical area, some significant differences between the two techniques was detected.
  
  
  CONCLUSIONS
  Within the limitations of this study, the RT is an accurate and reliable technique that can simulate crown gap space after cementation.
  
  
  CONCLUSIONS
  The RT is reliable for evaluating cement thickness at the marginal and internal gaps of Procera AllCeram crowns during try-in sessions.
authors.affiliation: Department of Fixed Prosthodontics, St-Joseph University in Beirut, Lebanon. habibrahme@hotmail.com
authors.forename: Habib Y
authors.initials: HY
authors.lastname: Rahme
authors.forename: Georges E
authors.initials: GE
authors.lastname: Tehini
authors.forename: Salim M
authors.initials: SM
authors.lastname: Adib
authors.forename: Albert S
authors.initials: AS
authors.lastname: Ardo
authors.forename: Khaldoun T
authors.initials: KT
authors.lastname: Rifai
mesh_terms: D001641:Bicuspid; D002484:Cementation; D003442:Crowns; D003760:Dental Impression Materials; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain; D017267:Dental Prosthesis Design / Q000379:methods*; D005899:Glass Ionomer Cements; D007180:Incisor; D003765:Models, Dental; D011145:Polyvinyls; D017755:Prosthesis Fitting; D012833:Siloxanes
chemical_list: D003760:Dental Impression Materials; D005899:Glass Ionomer Cements; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane; D003776:Dental Porcelain