title: A 3-year follow-up study of preformed beta-quartz glass-ceramic insert restorations.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the clinical performance of preformed beta-quartz glass-ceramic insert restorations.
  
  
  METHODS
  Nine Class I and 30 Class II beta-quartz glass-ceramic insert restorations were placed in 16 patients who were seen regularly by personnel at Umeå University Dental School. The California Dental Association criteria were used to evaluate the restorations at baseline, 6 months, and 1, 2, and 3 years after luting. The occurrence of postoperative sensitivity, the time taken to manufacture each restoration, and certain periodontal conditions were also evaluated.
  
  
  RESULTS
  Sixty-nine percent of the restorations were rated satisfactory at the 3-year examination. During the follow-up period, 4 became loose and 7 were fractured or had flaking surfaces. Caries was registered in connection with 1 restoration. Excellent ratings were obtained for marginal integrity, anatomic form, surface, and color in 62%, 84%, 32%, and 44% of the restorations, respectively. There was no statistically significant difference in the occurrence of plaque and bleeding on probing in comparison with the controls. The mean overall time for placement was 38 minutes. The estimated survival rate (Kaplan-Meier) was 59% after 3.5 years.
  
  
  CONCLUSIONS
  The quality of the beta-quartz glass-ceramic restorations in the present study was inferior to that presented in most earlier studies of ceramic or resin composite posterior restorations placed in patients treated at university clinics. Both the technique and the beta-quartz glass-ceramic inserts have to be evaluated in more long-term studies to assess the possibility of their serving as an alternative restorative technique.
authors.affiliation: Department of Dental Materials Science, Umeå University, SE-901 87 Umeå, Sweden. Goran.Sjogren@odont.umu.se
authors.forename: G
authors.initials: G
authors.lastname: Sjögren
authors.forename: S O
authors.initials: SO
authors.lastname: Hedlund
authors.forename: C
authors.initials: C
authors.lastname: Jonsson
authors.forename: A
authors.initials: A
authors.lastname: Sandström
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001641:Bicuspid; D002516:Ceramics / Q000737:chemistry; D003116:Color; D003731:Dental Caries / Q000145:classification; D018772:Dental Marginal Adaptation; D003773:Dental Plaque / Q000145:classification; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000145:classification; D005260:Female; D005500:Follow-Up Studies; D005884:Gingival Hemorrhage / Q000145:classification; D005898:Glass / Q000737:chemistry; D006801:Humans; D007284:Inlays / Q000145:classification; D008297:Male; D008875:Middle Aged; D008963:Molar; D011791:Quartz / Q000737:chemistry; D013499:Surface Properties; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: C088834:Beta-Quartz glass-ceramic; D011791:Quartz