title: Prospective cohort clinical study assessing the 5-year survival and success of anterior maxillary zirconia-based crowns with customized zirconia copings.
abstract: BACKGROUND
  Studies evaluating anterior zirconia-based crowns are limited.
  
  
  OBJECTIVE
  The purpose of this prospective cohort clinical study was to assess the efficacy of zirconia-based anterior maxillary crowns with 0.3-mm customized copings at the cervical third and anatomical design elsewhere for up to 5 years of service.
  
  
  METHODS
  Eighteen participants who required an anterior maxillary crown (n=20) and who had signed a consent form approved by the University of Washington Health Sciences Center Human Subjects Division were enrolled. All preparations were standardized and prepared with an occlusal reduction of 1.5 to 2 mm and an axial reduction of 1 to 1.5 mm with 10 degrees of convergence angle. All finish lines were located on the sound tooth structure. Zirconia copings (Lava; 3M ESPE) were custom designed and milled to a 0.3-mm thickness at the cervical third and with selective thickness elsewhere to support the veneering porcelain. All restorations were luted with self-etching self-adhesive composite resin cement. Recall appointments were at 2 weeks, 6 months, and 12 months, and annually thereafter for 5 years. Modified Ryge criteria were used to assess the clinical fracture measurements, esthetics, marginal discoloration, marginal adaptation, radiographic proximal recurrent caries, and periapical pathoses. Descriptive statistics and 95% confidence intervals were used to describe the number and rate of complications and self-reported satisfaction with the crowns.
  
  
  RESULTS
  Twenty crowns with a mean follow-up of 58.7 months were evaluated. All crowns were rated as Alfa for fracture measurements (smooth surface, no fracture/chipping). Twelve crowns were rated esthetically as Romeo (no mismatch in color and shade) and 8 as Sierra (mismatch in color and shade within normal range). Twelve crowns were rated as Alfa (no visible evidence of crevice) and 8 as Bravo (visible evidence of crevice, no penetration of explorer) for marginal integrity. Nineteen were rated as Alfa (no discoloration) and 1 as Bravo (superficial discoloration) for marginal discoloration. No proximal caries or periapical pathoses were detected in 5 years. Participants were highly satisfied with their crowns after 5 years (mean ±SD: 9.8 ±0.4 on 0 to 10 scale).
  
  
  CONCLUSIONS
  Zirconia-based anterior maxillary crowns with customized copings with 0.3-mm thickness at the cervical third and zirconia margins performed well after 5 years of service.
authors.affiliation: Assistant Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash. Electronic address: samido@uw.edu.
authors.forename: Sami
authors.initials: S
authors.lastname: Dogan
authors.affiliation: Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
authors.forename: Ariel J
authors.initials: AJ
authors.lastname: Raigrodski
authors.affiliation: Associate Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
authors.forename: Hai
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Research Associate Professor, Department of Dental Public Health Sciences, University of Washington, Seattle, Wash.
authors.forename: Lloyd A
authors.initials: LA
authors.lastname: Mancl
mesh_terms: D000328:Adult; D000368:Aged; D003442:Crowns / Q000009:adverse effects / Q000592:standards; D003731:Dental Caries / Q000000981:diagnostic imaging / Q000209:etiology; D018772:Dental Marginal Adaptation; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla; D008875:Middle Aged; D011446:Prospective Studies; D017797:Prosthesis Coloring; D011861:Radiography, Dental; D015040:Zirconium / Q000627:therapeutic use*
chemical_list: D015040:Zirconium; C028541:zirconium oxide