title: A 1-year randomised controlled trial comparing zirconia versus metal-ceramic implant supported single-tooth restorations.
abstract: OBJECTIVE
  To compare the biological, technical and aesthetic outcomes of single implant-supported all-ceramic versus metal-ceramic crowns.
  
  
  METHODS
  Thirty-six patients with premolar agenesis were randomly treated with 38 all-ceramic (AC) and 37 metal-ceramic (MC) implant-supported single-tooth restorations. A quasi-randomisation of consecutively included restorations in patients with one or more implants was used, i.e. a combination of parallel group (for 13 patients with one restoration) and split-mouth (for 23 patients with ≥2 restorations). All patients were recalled for baseline and 1-year followup examinations. Biological and technical outcomes, including complications, were clinically and radiographically registered. The Copenhagen Index Score and visual analogue scale (VAS) score were used to assess professional and patient-reported aesthetic outcomes, respectively, by blinded assessors.
  
  
  RESULTS
  One-year after loading, no patient dropped out and no implant failed, though one MC restoration had to be remade. The marginal bone loss was not significantly different between AC and MC restorations (AC: mean 0.08 mm, SD 0.25; MC: mean 0.10 mm, SD 0.17). Seven out of 10 inflammatory reactions were registered at AC restorations. Two technical complications, one loss of retention and one chipping of veneering porcelain were recorded at two metal-ceramic crowns. The marginal adaptation of the all-ceramic crowns was significantly less optimal than the metal-ceramic crowns (P = 0.014). The professional-reported colour match of all-ceramic crowns was significantly better than metal-ceramic crowns (P = 0.031), but other aesthetic parameters as well as the VAS scores demonstrated no statistically significant difference between AC and MC restorations.
  
  
  CONCLUSIONS
  Marginal bone loss and the aesthetic outcomes were not significantly different between AC and MC restorations in this short-term follow-up study, though inflammatory reactions in the peri-implant mucosa as well as less optimal marginal adaptation were more frequently registered for all-ceramic compared to the metal-ceramic crowns.
authors.affiliation: Department of Oral Rehabilitation, University of Copenhagen, Copenhagen, Denmark. Mandana.Hosseini@sund.ku.dk
authors.forename: Mandana
authors.initials: M
authors.lastname: Hosseini
authors.forename: Nils
authors.initials: N
authors.lastname: Worsaae
authors.forename: Morten
authors.initials: M
authors.lastname: Schiodt
authors.forename: Klaus
authors.initials: K
authors.lastname: Gotfredsen
mesh_terms: D000328:Adult; D016301:Alveolar Bone Loss / Q000209:etiology; D000848:Anodontia / Q000534:rehabilitation; D001641:Bicuspid / Q000002:abnormalities; D003116:Color; D003442:Crowns; D019250:Dental Implants, Single-Tooth; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D017269:Dental Prosthesis Repair; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D004955:Esthetics, Dental; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D008875:Middle Aged; D017060:Patient Satisfaction; D010512:Periodontal Index; D011183:Postoperative Complications; D013280:Stomatitis / Q000209:etiology; D013499:Surface Properties; D016896:Treatment Outcome; D055815:Young Adult; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D016876:Metal Ceramic Alloys; D015040:Zirconium; C028541:zirconium oxide