title: Hardware complications and failure of three-unit zirconia-based and porcelain-fused-metal implant-supported fixed dental prostheses: a retrospective cohort study with up to 8 years.
abstract: OBJECTIVE
  The aim of the present study was to assess the hardware complications and survival of three-unit implant-supported zirconia-based fixed dental prostheses (IZ) and implant-supported porcelain-fused-metal fixed dental prostheses (IP).
  
  
  METHODS
  The study is a retrospective cohort study with up to 8 years (mean 4.8 years) follow-up. Patients with conventional three-unit implant-supported fixed dental prostheses (without cantilever) in posterior area were reviewed. Hardware complications and survival rate were evaluated. Chi-Square test was used to test the difference between IZ and IP groups.
  
  
  RESULTS
  Two hundred and thirty-seven patents (IZ : 112, IP : 125) with 279 three-unit restorations (IZ : 127, IP : 152) participated in the study. The overall survival rate was 95.3% in IZ group and 94.7% in IP group at implant-level and 94.6% in IZ group and 94.4% in IP group at subject-level. Veneer chipping was the most frequently seen complication (20.1%). Significant higher minor veneer chipping rate (Grade 1) was found in IZ group (P = 0.04). No significant difference of veneer chipping rate (Grade 2 and Grade 3) was found between the two groups. The overall hardware complication rates of IZ were significantly higher than IP (33.07% and 18.42%, P = 0.01).
  
  
  CONCLUSIONS
  High survival rate of zirconia-base and Porcelain-fused-to-metal (PFM) restorations can be achieved with up to 8 years follow-up. The zirconia-based restorations need more polishing procedures, maintenance, and professional care than PFM restorations. The number of implants supporting a fixed dental prosthesis did not influence the implant survival and hardware complications. Well-designed studies with high evidence level are still needed to further explore the hardware complications and clinical survival of IZ and IP.
authors.affiliation: Department of Oral and Maxillo-facial Implantology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiaotong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Jun-Yu
authors.initials: JY
authors.lastname: Shi
authors.affiliation: Department of Oral and Maxillo-facial Implantology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiaotong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Xiao-Meng
authors.initials: XM
authors.lastname: Zhang
authors.affiliation: Department of Oral and Maxillo-facial Implantology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiaotong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Shi-Chong
authors.initials: SC
authors.lastname: Qiao
authors.affiliation: Department of Oral and Maxillo-facial Implantology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiaotong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Shu-Jiao
authors.initials: SJ
authors.lastname: Qian
authors.affiliation: Department of Oral and Maxillo-facial Implantology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiaotong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Jia-Ji
authors.initials: JJ
authors.lastname: Mo
authors.affiliation: Department of Oral and Maxillo-facial Implantology, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiaotong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Hong-Chang
authors.initials: HC
authors.lastname: Lai
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003776:Dental Porcelain; D019094:Dental Prosthesis, Implant-Supported / Q000009:adverse effects* / Q000295:instrumentation; D019232:Dental Restoration Failure; D003830:Denture, Partial, Fixed / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide
keywords: dental implants; hardware complications; survival rates; zirconia