title: In vitro fracture resistance of posterior metal-ceramic and all-ceramic inlay-retained resin-bonded fixed partial dentures.
abstract: BACKGROUND
  Inlay-retained resin-bonded fixed partial dentures (RBFPDs) are conservative prosthetic restorations; however, their resistance to fracture is not clear.
  
  
  OBJECTIVE
  The purpose of this study was to compare fracture loads of posterior complete coverage metal-ceramic restorations with all-ceramic inlay-retained RBFPDs.
  
  
  METHODS
  Thirty-two posterior ceramic RBFPD restorations were divided into 4 groups (n=8): (1) Complete metal-ceramic fixed partial dentures (MC-FPDs) fabricated of Ni-Cr-based alloy (Wirolloy) and veneered with a ceramic (IPS d.SIGN) as the control group; (2) inlay-retained metal-ceramic (MC RBFPDs) with the same materials as the control; (3) inlay-retained lithium disilicate (LD) glass-ceramic (IPS Empress 2) RBFPDs; and (4) inlay-retained zirconia-based (Z) ceramic (Cercon) RBFPDs. Control specimens were prepared to receive conventional complete MC-FPDs designed to include a 1.3-mm-circumferential, 90-degree flat shoulder with rounded angles. Inlay-retained RBFPD specimens were prepared with 2-mm occlusal reduction but without bevels at the occlusal or gingival margins. Specimens were loaded and fracture loads (N) measured at fracture with a universal testing machine at a crosshead speed of 1.0 mm/min and 250 kgf load cell. Data were analyzed with 1-way ANOVA and Duncan test (alpha=.001).
  
  
  RESULTS
  Fracture loads (mean +/- SD) were greatest for control specimens (1318.43 +/- 211.00 N) and Z-RBFPD (1247.70 +/- 262.51 N) specimens as compared to MC-RBFPD or LD-RBFPD (P < .001). MC-RBFPD exhibited the next highest fracture loads (958.01 +/- 194.29 N), and LD-RBFPD exhibited the significantly lowest values (303.23 +/- 92.54 N) of the materials tested (P < .001).
  
  
  CONCLUSIONS
  Inlay-retained zirconia-based ceramic RBFPDs demonstrated the greatest fracture resistance among all inlay-retained restorations tested.
authors.affiliation: Ankara Dental Hospital, Ankara University, Ankara, Turkey.
authors.forename: Mehmet A
authors.initials: MA
authors.lastname: Kiliçarslan
authors.forename: P Sema
authors.initials: PS
authors.lastname: Kedici
authors.forename: H Cenker
authors.initials: HC
authors.lastname: Küçükeşmen
authors.forename: Bülent C
authors.initials: BC
authors.lastname: Uludağ
mesh_terms: D002516:Ceramics; D019245:Compressive Strength; D003764:Dental Materials; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis / Q000379:methods*; D003779:Denture Design; D016379:Denture, Partial, Fixed, Resin-Bonded; D006801:Humans; D018020:Lithium Compounds; D008422:Materials Testing / Q000379:methods*; D016876:Metal Ceramic Alloys; D015040:Zirconium
chemical_list: D003764:Dental Materials; C118557:Empress 2; D018020:Lithium Compounds; D016876:Metal Ceramic Alloys; D015040:Zirconium; C028541:zirconium oxide