title: Evaluation of the marginal fit of metal copings fabricated on three different marginal designs using conventional and accelerated casting techniques: an in vitro study.
abstract: BACKGROUND
  Abundant resources and techniques have been used for complete coverage crown fabrication. Conventional investing and casting procedures for phosphate-bonded investments require a 2- to 4-h procedure before completion. Accelerated casting techniques have been used, but may not result in castings with matching marginal accuracy.
  
  
  OBJECTIVE
  The study measured the marginal gap and determined the clinical acceptability of single cast copings invested in a phosphate-bonded investment with the use of conventional and accelerated methods.
  
  
  METHODS
  One hundred and twenty cast coping samples were fabricated using conventional and accelerated methods, with three finish lines: Chamfer, shoulder and shoulder with bevel. Sixty copings were prepared with each technique. Each coping was examined with a stereomicroscope at four predetermined sites and measurements of marginal gaps were documented for each.
  
  
  METHODS
  A master chart was prepared for all the data and was analyzed using Statistical Package for the Social Sciences version. Evidence of marginal gap was then evaluated by t-test. Analysis of variance and Post-hoc analysis were used to compare two groups as well as to make comparisons between three subgroups .
  
  
  RESULTS
  Measurements recorded showed no statistically significant difference between conventional and accelerated groups.
  
  
  CONCLUSIONS
  Among the three marginal designs studied, shoulder with bevel showed the best marginal fit with conventional as well as accelerated casting techniques. Accelerated casting technique could be a vital alternative to the time-consuming conventional casting technique. The marginal fit between the two casting techniques showed no statistical difference.
authors.affiliation: Department of Prosthodontics and Implantology, Bhojia Dental College and Hospital, Baddi, Solan, Himachal Pradesh, India.
authors.forename: Sharad
authors.initials: S
authors.lastname: Vaidya
authors.forename: Hari
authors.initials: H
authors.lastname: Parkash
authors.forename: Akshay
authors.initials: A
authors.lastname: Bhargava
authors.forename: Sharad
authors.initials: S
authors.lastname: Gupta
mesh_terms: D017076:Computer-Aided Design; D003442:Crowns / Q000592:standards; D003722:Dental Alloys / Q000737:chemistry*; D003734:Dental Casting Investment / Q000737:chemistry; D003735:Dental Casting Technique / Q000592:standards*; D018772:Dental Marginal Adaptation; D017267:Dental Prosthesis Design; D006801:Humans; D008422:Materials Testing; D010710:Phosphates / Q000737:chemistry; D011446:Prospective Studies; D013499:Surface Properties; D019231:Tooth Preparation, Prosthodontic / Q000379:methods; D014885:Waxes / Q000737:chemistry
chemical_list: D003722:Dental Alloys; D003734:Dental Casting Investment; D010710:Phosphates; D014885:Waxes