title: A 3 years retrospective study of survival for zirconia-based single crowns fabricated from intraoral digital impressions.
abstract: OBJECTIVE
  To evaluate the clinical performance of glass-ceramic/zirconia crowns fabricated using intraoral digital impressions - a retrospective study with a three-year follow-up.
  
  
  METHODS
  70 consecutive patients with a total of 86 glass-ceramic/zirconia crowns were treated by a single clinician using standardized clinical and laboratory protocols. A complete digital workflow was adopted for the purpose except for the veneering procedure for the glass-ceramic crowns. Occlusal adjustments were made before the ceramic glazing procedure. Before cementation, all abutments where carefully cleaned with a 70% alcoholic solution and air dried. Cementation was performed using dual-curing, self-adhesive resin cement. Patients were re-examined after 12, 24 and 36 months, to assess crown chipping/fractures.
  
  
  RESULTS
  After the three-year follow-up, none of the zirconia-based restoration was lost ("apparent" survival rate 100%) otherwise, the chipping rate of the veneering material increased from 9.3% after 12 months, to 14% after 24 months to 30.2% after 36 months. As a consequence, the "real" success rate after 3 years was 69.8%.
  
  
  CONCLUSIONS
  After 3 years the success rate of zirconia-based crowns was 69.8%, while the incidence of the chipping was 30.2%. Assuming an exponential increase in chipping rate between 12 and 36 months it can be argued that, among others, the fatigue-mechanism could be advocated as the main factor for the failure of glass-ceramic veneered zirconia especially after 24 months.
authors.affiliation: Department of Dentistry, Vita Salute University, San Raffaele Hospital, Milan, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Gherlone
authors.affiliation: Department of Dentistry, Vita Salute University, San Raffaele Hospital, Milan, Italy. Electronic address: federico.mandelli@gmail.com.
authors.forename: Federico
authors.initials: F
authors.lastname: Mandelli
authors.affiliation: Department of Dentistry, Vita Salute University, San Raffaele Hospital, Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Capparè
authors.affiliation: Faculty of Psychology, San Raffaele University of Milan, Italy; Department of Dentistry, Vita Salute University, San Raffaele Hospital, Milan, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pantaleo
authors.affiliation: Department of Dentistry, Vita Salute University, San Raffaele Hospital, Milan, Italy; Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, Chieti, Italy.
authors.forename: Tonino
authors.initials: T
authors.lastname: Traini
authors.affiliation: Department of Dentistry, Vita Salute University, San Raffaele Hospital, Milan, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Ferrini
mesh_terms: D000328:Adult; D002484:Cementation / Q000379:methods; D002516:Ceramics / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns; D000044:Dental Abutments; D003761:Dental Impression Technique; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003801:Dental Veneers; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D019558:Occlusal Adjustment; D019279:Resin Cements / Q000737:chemistry; D012189:Retrospective Studies; D016019:Survival Analysis; D057188:Workflow; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D019279:Resin Cements; C023506:Glass ceramics; D015040:Zirconium; C028541:zirconium oxide
keywords: CAD/CAM; Chipping; Fracture; Veneer; Zirconia crown