title: In vitro wear simulation measurements of composite versus resin-modified glass ionomer luting cements for all-ceramic restorations.
abstract: BACKGROUND
  Although composite cements are generally indicated for cementation of all-ceramic restorations, some manufacturers of dental cements propose that resin-modified glass ionomers (RMGIs) may be used for cementation of high-strength ceramic restorations.
  
  
  OBJECTIVE
  This study was undertaken to compare the in vitro abrasion and attrition wear of two dual-cure cements (in dual-cure and self-cure modes) and two RMGI cements when placed between ceramic and enamel to simulate the margin of a restoration.
  
  
  METHODS
  Rectangular fragments of pressed ceramic (Empress 2) were cemented between the halves of bovine incisors sectioned mesiodistally, using one of the following materials: RelyX ARC, Variolink II, RelyX Luting, or ProTec CEM. The two resin cements were tested in dual-cure and self-cure modes. A three-body wear test was performed in the new Oregon Health Sciences University (OHSU) oral wear simulator (100,000 cycles; abrasion load: 20 N; attrition load: 90 N). Degree of conversion of resin cements was determined by Fourier transform infrared spectroscopy. Results were analyzed by analysis of variance and Tukey's test (p = .05). Epoxy replicas of wear specimens were observed in the scanning electron microscope.
  
  
  RESULTS
  No significant differences in abrasion wear (RelyX ARC dual-cure: 11 +/- 4.4 microm; RelyX ARC self-cure: 17 +/- 7.0 microm; Variolink dual-cure: 14 +/- 8.6 microm; Variolink self-cure: 23 +/- 10.7 microm) or attrition wear (RelyX ARC dual-cure: 18 +/- 6.4 microm; RelyX ARC self-cure: 31 +/- 4.5 microm; Variolink dual-cure: 32 +/- 6.8 microm; Variolink self-cure: 39 +/- 15.9 microm) were found between activation modes of the resin cements. ProTec CEM (32 +/- 8.7 microm) showed abrasion similar to that of Variolink II and RelyX ARC self-cure. Resin-modified glass ionomers showed more attrition wear than the resin cements (ProTec CEM: 62 +/- 13.0 microm; RelyX Luting: 69 +/- 7.1 microm). RelyX ARC showed a similar degree of conversion for both activation modes (dual-cure: 70 +/- 4.3%; self-cure: 68 +/- 1.2%), but Variolink II had a higher degree of conversion in dual-cure mode (67 +/- 0.5% vs 60 +/- 1.0%). Cement wear was accompanied by marginal breakdown and increased surface roughness of enamel and ceramic.
  
  
  CONCLUSIONS
  The activation mode of resin cements did not influence their wear resistance. The RMGIs underwent higher attrition wear than the resin cements.
  
  
  CONCLUSIONS
  Increased submargination associated with marginal breakdown and increased roughness of the surrounding structures may be expected when ceramic inlays are cemented with resin-modified glass ionomers.
authors.affiliation: Department of Dental Materials, University of São Paulo, School of Dentistry, São Paulo, Brazil. bragar@ohsu.edu
authors.forename: Roberto R
authors.initials: RR
authors.lastname: Braga
authors.forename: John R
authors.initials: JR
authors.lastname: Condon
authors.forename: Jack L
authors.initials: JL
authors.lastname: Ferracane
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002417:Cattle; D002484:Cementation; D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003743:Dental Enamel / Q000648:ultrastructure; D003776:Dental Porcelain / Q000737:chemistry; D019554:Dental Restoration Wear; D003793:Dental Restoration, Permanent; D005899:Glass Ionomer Cements / Q000737:chemistry*; D018020:Lithium Compounds / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013223:Statistics as Topic; D013499:Surface Properties
chemical_list: D003188:Composite Resins; C118557:Empress 2; D005899:Glass Ionomer Cements; D018020:Lithium Compounds; D011109:Polymethacrylic Acids; C091610:Protech glass ionomer cement; C462240:RelyX ARC; D019279:Resin Cements; D003776:Dental Porcelain; C103502:Variolink; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate