title: Assessment of shoulder dimensions and angles of porcelain bonded to metal crown preparations.
abstract: The metal ceramic crown is the most popular extracoronal restoration in the United Kingdom. These restorations may fail because of fracture or esthetics. A potential cause of failure is the quality and width of the facial shoulder preparation. In this study 24 extracted human teeth were prepared to receive metal ceramic crowns by one of three dentists. Preparations were replicated and scanned in the midfacial plane by a coordinate measuring machine with a noncontact probe. The x, y, and z surface coordinates were recorded. The results indicated a mean (+/-SD) shoulder width value of 0.752 mm (+/-0.174 mm) and a shoulder angle of 108.54 (+/-15.06) degrees. From these data it would appear that there are deficiencies in shoulder preparations, particularly in width. These inadequacies may have implications for longevity of the restoration and periodontal health in a clinical situation.
authors.affiliation: Department of Conservative Dentistry, Dental School, London Hospital Medical College, United Kingdom.
authors.forename: K
authors.initials: K
authors.lastname: Seymour
authors.forename: L
authors.initials: L
authors.lastname: Zou
authors.forename: D Y
authors.initials: DY
authors.lastname: Samarawickrama
authors.forename: E
authors.initials: E
authors.lastname: Lynch
mesh_terms: D003196:Computer Graphics; D003442:Crowns; D017267:Dental Prosthesis Design; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D006801:Humans; D016876:Metal Ceramic Alloys; D009811:Odontometry; D011475:Prosthesis Failure; D015203:Reproducibility of Results
chemical_list: D016876:Metal Ceramic Alloys