title: A laboratory evaluation of the construction of resin-bonded cast restorations.
abstract: OBJECTIVE
  To compare the effect of two construction techniques and two pattern materials on the fit of resin-bonded cast restorations.
  
  
  METHODS
  In-vitro study carried out by one operator.
  
  
  METHODS
  Postgraduate university hospital.
  
  
  METHODS
  65 nickel-chrome castings were constructed using refractory die and lift-off techniques with wax and acrylic resin pattern material. They were cemented onto master silver dies, embedded in self-curing acrylic resin and sectioned along their long axes. Interfacial distance between the master silver die and casting was measured.
  
  
  RESULTS
  A significant different between the range of figures in each group (Mann-Whitney Test, P < 0.01) was found. Construction techniques can be ranked in order of fit of castings: 1. Refractory die, wax patterns: 42.6 microns (SD 12.03). 2. Refractory die, acrylic resin patterns: 53.7 microns (SD.16.06).3. Conventional technique, acrylic resin patterns: 85.5 microns (SD 31.62). 4. Lift-off technique, wax patterns: 139 microns (SD 53.15).5. Lift-off technique, acrylic patterns: 172.8 microns (SD 74.04).
  
  
  CONCLUSIONS
  Castings constructed using refractory die technique and subsequently cemented resulted in a more accurate and less variable fit than those produced with the lift-off technique. Wax patterns lead to more accurate castings than acrylic resin and locating indentations may interfere with the cementation of castings when lift-off techniques are used.
authors.affiliation: Conservation Department, Eastman Dental Institute, London.
authors.forename: H S
authors.initials: HS
authors.lastname: Chana
authors.forename: G J
authors.initials: GJ
authors.lastname: Pearson
authors.forename: R J
authors.initials: RJ
authors.lastname: Ibbetson
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D002484:Cementation; D002858:Chromium Alloys / Q000737:chemistry; D001840:Dental Bonding; D003734:Dental Casting Investment / Q000737:chemistry; D003735:Dental Casting Technique; D003793:Dental Restoration, Permanent / Q000379:methods; D005069:Evaluation Studies as Topic; D006801:Humans; D007283:Inlay Casting Wax / Q000737:chemistry; D007754:Laboratories, Dental; D003765:Models, Dental; D010710:Phosphates / Q000737:chemistry; D019279:Resin Cements; D012834:Silver; D013499:Surface Properties
chemical_list: D000180:Acrylic Resins; D002858:Chromium Alloys; D003734:Dental Casting Investment; D010710:Phosphates; D019279:Resin Cements; D012834:Silver; D007283:Inlay Casting Wax; C052304:Panavia EX