title: In vitro performance and fracture resistance of CAD/CAM-fabricated implant supported molar crowns.
abstract: OBJECTIVE
  The aim of this study is to investigate the performance and fracture resistance of different CAD/CAM ceramic and composite materials as implant- or tooth-supported single crowns with respect to the clinical procedure (screwed/bonded restoration).
  
  
  METHODS
  One hundred twenty crowns were fabricated on implants or human molar teeth simulating (a) chairside procedure ([CHAIR] implant crown bonded to abutment), (b) labside procedure ([LAB] abutment and implant crown bonded in laboratory, screwed chairside), and (c) reference ([TOOTH] crowns luted on human teeth). Four materials were investigated: ZLS (zirconia-reinforced lithium silicate ceramic; Celtra Duo, Degudent: polished (P)/crystallized (C)), RB (resin-based composite; Cerasmart, GC), and RIC (resin-infiltrated ceramic; Enamic, Vita-Zahnfabrik). LiS (lithiumdisilicate; Emax CAD, Ivoclar-Vivadent) served as reference. Combined thermal cycling and mechanical loading (TCML) was performed simulating a 5-year clinical situation. Fracture force was determined. Data were statistically analyzed (Kolmogorov-Smirnov test, one-way ANOVA; post hoc Bonferroni, α = 0.05).
  
  
  RESULTS
  One crown of ZLS_C[LAB] (1,200,000 cycles) and RB[CHAIR] (890 cycles) failed during TCML. Fracture values varied between 977.7 N(RB) and 3070.4 N(LiS)[CHAIR], 1130.6 N(RB) and 2998.1 N(LiS)[LAB], and 1802.4 N(ZLS) and 2664.3 N(LiS)[TOOTH]. Significantly (p < 0.003) different forces were found between the materials in all three groups. ZLS_C, RIC, and RB showed significantly (p < 0.014) different values for the individual groups.
  
  
  CONCLUSIONS
  Partly ceramic and resin-based materials performed differently on implant or tooth abutments. The insertion of a screw channel reduced the stability for individual crown materials. Insertion of the screw channel should be performed carefully.
  
  
  CONCLUSIONS
  All restorations were in a range where clinical application seems not restricted, but insertion of a screw channel might reduce stability of individual materials.
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042, Regensburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Rosentritt
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042, Regensburg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Hahnel
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042, Regensburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Engelhardt
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042, Regensburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Behr
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042, Regensburg, Germany. verena.preis@ukr.de.
authors.forename: Verena
authors.initials: V
authors.lastname: Preis
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D066298:In Vitro Techniques; D015040:Zirconium / Q000737:chemistry
chemical_list: D003188:Composite Resins; C493120:lithia disilicate; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide
keywords: Abutment; CAD/CAM composites/ceramics; Chewing simulation; Fracture resistance; Implant crown; Zirconia-reinforced lithium silicate