title: In vitro study of fracture incidence and compressive fracture load of all-ceramic crowns cemented with resin-modified glass ionomer and other luting agents.
abstract: BACKGROUND
  Anecdotal reports based on clinical observation have recently linked resin-modified glass ionomer luting agents with postcementation fracture of all-ceramic crowns.
  
  
  OBJECTIVE
  This study evaluated the fracture incidence of In-Ceram and VitaDur Alpha porcelain jacket all-ceramic crowns cemented with 5 luting agents (Fuji I, Fuji Plus, Vitremer, Advance, and Panavia 21) during 2 months storage in 0.8% NaCl solution.
  
  
  METHODS
  Fifty human maxillary premolar teeth were prepared for each ceramic system and divided into 5 subgroups of 10 teeth to be cemented with 5 luting cements. Specimens were observed for fracture lines and crack initiation at storage times up to 2 months. Incidence of fracture was analyzed with Fisher's Exact test. Specimens that did not fracture during storage were loaded in compression to failure. Failure loads were analyzed by analysis of variance and multiple pairwise comparisons.
  
  
  RESULTS
  Only all-ceramic crowns cemented with Advance cement fractured during the 2-month observation period, and porcelain jacket crowns were found to fracture earlier and more frequently than In-Ceram crowns. Cracks initiated at the crown margin, and multiple crack lines were found as the time of storage increased. In-Ceram crowns were significantly stronger (140 +/- 21.5 kg) than porcelain jacket crowns (98.6 +/- 17.8 kg) at P <.05. For In-Ceram crowns, cement type did not influence failure load while for porcelain jacket crowns, Fuji I (110.5 kg) was significantly higher than Vitremer (86.6 kg) at P <.05.
  
  
  CONCLUSIONS
  For the cements studied, only crowns cemented with Advance cement demonstrated fracture during 2-month storage. Results for the true resin-modified glass ionomer cements do not support anecdotal reports of fracture of all-ceramic crowns cemented with these materials.
authors.affiliation: School of Dentistry, Indiana University, Indianapolis, IN, USA.
authors.forename: C
authors.initials: C
authors.lastname: Leevailoj
authors.forename: J A
authors.initials: JA
authors.lastname: Platt
authors.forename: M A
authors.initials: MA
authors.lastname: Cochran
authors.forename: B K
authors.initials: BK
authors.lastname: Moore
mesh_terms: D002484:Cementation / Q000379:methods* / Q000706:statistics & numerical data; D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D003442:Crowns / Q000706:statistics & numerical data; D019232:Dental Restoration Failure; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing / Q000379:methods / Q000706:statistics & numerical data; D019279:Resin Cements / Q000737:chemistry*; D013997:Time Factors
chemical_list: D003188:Composite Resins; D005899:Glass Ionomer Cements; D019279:Resin Cements