title: Assessment of convergence angle of full-coverage porcelain fused to metal crowns in clinical practice.
abstract: BACKGROUND
  Full-coverage porcelain fused to metal crowns is commonly recommended for restoration of extensively damaged teeth. Ability of the dentist to adequately prepare teeth is fundamental to success and longevity of these restorations.
  
  
  OBJECTIVE
  This study was designed to compare recommended convergence angle and taper values of tooth preparation with clinically practiced values and to assess the factors such as tooth position, operator experience, vitality, and restorative status on convergence angle of prepared teeth.
  
  
  METHODS
  It was a descriptive, cross-sectional study design and held at The Aga Khan University Hospital, Dental Section, for a period of 1 year.
  
  
  METHODS
  A minimum of 197 crown preparation models of molar and premolar teeth prepared by residents and specialists were collected in order to achieve the objectives of the study on the basis of convenient sampling technique.
  
  
  METHODS
  One sample t-test used to compare the mean practiced convergence angle values with its recommended values. Independent sample t-test and one-way ANOVA was used to see difference in the convergence angle values of the teeth prepared by different operators, tooth type, vitality status, and restorative status of teeth.
  
  
  RESULTS
  Mean reported convergence angle and axial wall taper values were 23.7° ± 8.9° and 11.3° ± 7.8°, respectively, which is significantly greater (P<0.001) than the recommended values. Convergence angle values were greater for molars as compared to premolars.
  
  
  CONCLUSIONS
  There was a considerable disparity between the convergent angles values recorded in this study and the recommended guidelines and are affected by tooth type, vitality, and restorative status of tooth.
authors.affiliation: Department of Surgery, Dental Section, The Aga Khan University Hospital, Karachi, Pakistan.
authors.forename: Robia
authors.initials: R
authors.lastname: Ghafoor
authors.forename: Azfar A
authors.initials: AA
authors.lastname: Siddiqui
authors.forename: Munawar
authors.initials: M
authors.lastname: Rahman
mesh_terms: D001641:Bicuspid / Q000033:anatomy & histology; D002983:Clinical Competence; D003430:Cross-Sectional Studies; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry*; D019983:Guideline Adherence; D006801:Humans; D007396:Internship and Residency; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D008963:Molar / Q000033:anatomy & histology; D017410:Practice Guidelines as Topic; D019239:Practice Patterns, Dentists'; D011476:Prosthodontics / Q000193:education; D012189:Retrospective Studies; D019231:Tooth Preparation, Prosthodontic / Q000379:methods*; D019553:Tooth, Nonvital / Q000473:pathology
chemical_list: D016876:Metal Ceramic Alloys; D003776:Dental Porcelain