title: A comparison of the accuracy of patterns processed from an inlay casting wax, an auto-polymerized resin and a light-cured resin pattern material.
abstract: BACKGROUND
  Traditionally, inlay casting waxes have been used to fabricate patterns for castings. Newer resin pattern materials offer greater rigidity and strength, allowing easier laboratory and intraoral adjustment without the fear of pattern damage. They also claim to possess a greater dimensional stability when compared to inlay wax.
  
  
  OBJECTIVE
  This study attempted to determine and compare the marginal accuracy of patterns fabricated from an inlay casting wax, an autopolymerized pattern resin and a light polymerized pattern resin on storage off the die for varying time intervals.
  
  
  METHODS
  Ten patterns each were fabricated from an inlay casting wax (GC Corp., Tokyo, Japan), an autopolymerized resin pattern material (Pattern resin, GC Corp, Tokyo, Japan) and a light-cured resin pattern material (Palavit GLC, Hereaus Kulzer GmbH, Germany). The completed patterns were stored off the die at room temperature. Marginal gaps were evaluated by reseating the patterns on their respective dies and observing it under a stereomicroscope at 1, 12, and 24 h intervals after pattern fabrication.
  
  
  RESULTS
  The results revealed that the inlay wax showed a significantly greater marginal discrepancy at the 12 and 24 h intervals. The autopolymerized resin showed an initial (at 1 h) marginal discrepancy slightly greater than inlay wax, but showed a significantly less marginal gap (as compared to inlay wax) at the other two time intervals. The light-cured resin proved to be significantly more dimensionally stable, and showed minimal change during the storage period.
  
  
  CONCLUSIONS
  The resin pattern materials studied, undergo a significantly less dimensional change than the inlay waxes on prolonged storage. They would possibly be a better alternative to inlay wax in situations requiring high precision or when delayed investment (more than 1 h) of patterns can be expected.
authors.affiliation: Department of Prosthodontics, Goa Dental College and Hospital Bambolim, Goa, India.
authors.forename: Praveen
authors.initials: P
authors.lastname: Rajagopal
authors.forename: Vidya
authors.initials: V
authors.lastname: Chitre
authors.forename: Meena A
authors.initials: MA
authors.lastname: Aras
mesh_terms: D003734:Dental Casting Investment / Q000737:chemistry*; D003735:Dental Casting Technique / Q000592:standards*; D003760:Dental Impression Materials / Q000737:chemistry; D018772:Dental Marginal Adaptation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007283:Inlay Casting Wax / Q000737:chemistry*; D008422:Materials Testing; D008768:Methylmethacrylates / Q000737:chemistry*; D058105:Polymerization; D019904:Polymethyl Methacrylate / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D003734:Dental Casting Investment; D003760:Dental Impression Materials; C082318:GC Pattern Resin; D008768:Methylmethacrylates; D007283:Inlay Casting Wax; D019904:Polymethyl Methacrylate