title: Accuracy of ringless casting and accelerated wax-elimination technique: a comparative in vitro study.
abstract: OBJECTIVE
  The purpose of this study was to determine whether the ringless casting and accelerated wax-elimination techniques can be combined to offer a cost-effective, clinically acceptable, and time-saving alternative for fabricating single unit castings in fixed prosthodontics.
  
  
  METHODS
  Sixty standardized wax copings were fabricated on a type IV stone replica of a stainless steel die. The wax patterns were divided into four groups. The first group was cast using the ringless investment technique and conventional wax-elimination method; the second group was cast using the ringless investment technique and accelerated wax-elimination method; the third group was cast using the conventional metal ring investment technique and conventional wax-elimination method; the fourth group was cast using the metal ring investment technique and accelerated wax-elimination method. The vertical marginal gap was measured at four sites per specimen, using a digital optical microscope at 100× magnification. The results were analyzed using two-way ANOVA to determine statistical significance.
  
  
  RESULTS
  The vertical marginal gaps of castings fabricated using the ringless technique (76.98 ± 7.59 μm) were significantly less (p < 0.05) than those castings fabricated using the conventional metal ring technique (138.44 ± 28.59 μm); however, the vertical marginal gaps of the conventional (102.63 ± 36.12 μm) and accelerated wax-elimination (112.79 ± 38.34 μm) castings were not statistically significant (p > 0.05).
  
  
  CONCLUSIONS
  The ringless investment technique can produce castings with higher accuracy and can be favorably combined with the accelerated wax-elimination method as a vital alternative to the time-consuming conventional technique of casting restorations in fixed prosthodontics.
authors.affiliation: Faculty, Prosthodontics and Dental Biomaterials Research, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Rahul
authors.initials: R
authors.lastname: Prasad
authors.forename: Abdulaziz Abdullah
authors.initials: AA
authors.lastname: Al-Keraif
authors.forename: Nidhi
authors.initials: N
authors.lastname: Kathuria
authors.forename: P V
authors.initials: PV
authors.lastname: Gandhi
authors.forename: S V
authors.initials: SV
authors.lastname: Bhide
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D003442:Crowns / Q000592:standards*; D003734:Dental Casting Investment / Q000737:chemistry; D003735:Dental Casting Technique / Q000295:instrumentation / Q000592:standards*; D045662:Dental Etching / Q000379:methods; D018772:Dental Marginal Adaptation; D017267:Dental Prosthesis Design / Q000592:standards*; D006801:Humans; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014885:Waxes / Q000737:chemistry
chemical_list: D003734:Dental Casting Investment; D016876:Metal Ceramic Alloys; D014885:Waxes; D000537:Aluminum Oxide
keywords: Phosphate-bonded investments; alloys; copings; marginal gaps