title: Fracture resistance of aluminium oxide and lithium disilicate-based crowns using different luting cements: an in vitro study.
abstract: OBJECTIVE
  The aim of this study was to investigate the fracture resistance of two types of ceramic crowns cemented with two different cements.
  
  
  METHODS
  Forty premolar crowns were fabricated using lithium-disilicate (IPS Empress-2) and glass-infiltrated aluminium-oxide (In-Ceram) ceramic systems. The crowns were divided into four groups (n=10) with Group 1 (IPS Empress-2) and Group 2 (In-Ceram) cemented with glass ionomer cement. Group 3 (IPS Empress-2) and Group 4 (In-Ceram) were cemented with resin cement. Crowns were tested in a universal testing machine at a compressive-load speed of 10 mm/min. Fracture modes were grouped into five categories. One way analysis of variance (ANOVA) and Bonferroni post-hoc tests were used to detect statistical significances (p<0.05).
  
  
  RESULTS
  The mean (SD) fracture resistance (Newtons) for Groups 1 to 4 were: 245.35 (82.69), 390.48 (67.03), 269.69 (10.33), and 418.36 (26.24). The cement type had no statistical significant effect (p>0.05) on fracture resistance within each ceramic system tested. In-Ceram crowns cemented with either glass ionomer or resin cements exhibited a statistically significantly higher fracture-resistance than IPS Empress-2 crowns (p<0.05). Minimal fracture in the test crowns was the common mode exhibited.
  
  
  CONCLUSIONS
  Fracture resistance of IPS Empress-2 and In-Ceram crowns was not affected by the type of cement used for luting.
  
  
  CONCLUSIONS
  Both In-Ceram and IPS Empress-2 crowns can be successfully luted with the cements tested with In-Ceram exhibiting higher fracture resistance than IPS Empress-2.
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, University of Science and Technology, Irbid, Jordan. ahed@just.edu.jo
authors.forename: Ahed M
authors.initials: AM
authors.lastname: Al-Wahadni
authors.forename: David L
authors.initials: DL
authors.lastname: Hussey
authors.forename: Nicholas
authors.initials: N
authors.lastname: Grey
authors.forename: Muhanad M
authors.initials: MM
authors.lastname: Hatamleh
mesh_terms: D000134:Acid Etching, Dental; D000537:Aluminum Oxide / Q000737:chemistry*; D002484:Cementation / Q000379:methods; D003442:Crowns; D003738:Dental Cements / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D018020:Lithium Compounds / Q000737:chemistry; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties
chemical_list: D003738:Dental Cements; D017220:Dentin-Bonding Agents; C118557:Empress 2; D005899:Glass Ionomer Cements; C483026:In-Ceram Alumina; D018020:Lithium Compounds; D019279:Resin Cements; C493120:lithia disilicate; D003776:Dental Porcelain; D000537:Aluminum Oxide