title: Probability of survival of implant-supported metal ceramic and CAD/CAM resin nanoceramic crowns.
abstract: OBJECTIVE
  To evaluate the probability of survival and failure modes of implant-supported resin nanoceramic relative to metal-ceramic crowns.
  
  
  METHODS
  Resin nanoceramic molar crowns (LU) (Lava Ultimate, 3M ESPE, USA) were milled and metal-ceramic (MC) (Co-Cr alloy, Wirobond C+, Bego, USA) with identical anatomy were fabricated (n=21). The metal coping and a burnout-resin veneer were created by CAD/CAM, using an abutment (Stealth-abutment, Bicon LLC, USA) and a milled crown from the LU group as models for porcelain hot-pressing (GC-Initial IQ-Press, GC, USA). Crowns were cemented, the implants (n=42, Bicon) embedded in acrylic-resin for mechanical testing, and subjected to single-load to fracture (SLF, n=3 each) for determination of step-stress profiles for accelerated-life testing in water (n=18 each). Weibull curves (50,000 cycles at 200N, 90% CI) were plotted. Weibull modulus (m) and characteristic strength (η) were calculated and a contour plot used (m versus η) for determining differences between groups. Fractography was performed in SEM and polarized-light microscopy.
  
  
  RESULTS
  SLF mean values were 1871N (±54.03) for MC and 1748N (±50.71) for LU. Beta values were 0.11 for MC and 0.49 for LU. Weibull modulus was 9.56 and η=1038.8N for LU, and m=4.57 and η=945.42N for MC (p>0.10). Probability of survival (50,000 and 100,000 cycles at 200 and 300N) was 100% for LU and 99% for MC. Failures were cohesive within LU. In MC crowns, porcelain veneer fractures frequently extended to the supporting metal coping.
  
  
  CONCLUSIONS
  Probability of survival was not different between crown materials, but failure modes differed.
  
  
  CONCLUSIONS
  In load bearing regions, similar reliability should be expected for metal ceramics, known as the gold standard, and resin nanoceramic crowns over implants. Failure modes involving porcelain veneer fracture and delamination in MC crowns are less likely to be successfully repaired compared to cohesive failures in resin nanoceramic material.
authors.affiliation: Department of Prosthodontics, University of Sao Paulo - Bauru College of Dentistry, Bauru, SP, Brazil. Electronic address: estevamab@gmail.com.
authors.forename: Estevam A
authors.initials: EA
authors.lastname: Bonfante
authors.affiliation: Department of Prosthodontics and Operative Dentistry, Tufts University School of Dental Medicine, Boston, MA, USA.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Department of Prosthodontics, University of Sao Paulo - Bauru College of Dentistry, Bauru, SP, Brazil.
authors.forename: Fábio C
authors.initials: FC
authors.lastname: Lorenzoni
authors.affiliation: Divisão de Metrologia de Materiais, Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Duque de Caxias, RJ, Brazil.
authors.forename: Lídia A
authors.initials: LA
authors.lastname: Sena
authors.affiliation: Department of Biomaterials and Biomimetics, New York University, New York, NY, USA.
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Hirata
authors.affiliation: Department of Prosthodontics, University of Sao Paulo - Bauru College of Dentistry, Bauru, SP, Brazil.
authors.forename: Gerson
authors.initials: G
authors.lastname: Bonfante
authors.affiliation: Department of Biomaterials and Biomimetics, New York University, New York, NY, USA; Department of Periodontology and Implant Dentistry, New York University College of Dentistry, New York, NY, USA; Division of Engineering, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.
authors.forename: Paulo G
authors.initials: PG
authors.lastname: Coelho
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns; D059605:Dental Implant-Abutment Design; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry*; D015203:Reproducibility of Results
keywords: Crown; Fatigue; Fractography; Implant; Metal ceramic; Resin nanoceramic; Step-stress accelerated life test; Weibull