title: Effect of cement space and delayed placement on the seating of crowns luted with Vitremer, Fuji Duet and Dyract Cem.
abstract: OBJECTIVE
  To determine the effects of cement space and delayed placement on the post-cementation elevation of crowns luted with two resin-modified glass ionomer luting cements (Vitremer, Fuji Duet) and a self-curing polyacid-modified composite resin luting cement (Dyract Cem).
  
  
  METHODS
  The investigation was conducted in two parts: (1) A loading apparatus was employed to simulate the seating of a crown on a die. Six dies, differing in the amount of cement space allowed from 6-52 microns, were used. The loading apparatus allowed for a test cement to be placed in the crown, and subsequent activation of the apparatus lead to seating of the die into the crown. After seating, post-cementation crown elevation was measured. The cements Phosphacap, Vitremer, Dyract Cem and Fuji Duet were used. Each cement was tested 10 times at each of the six cement spaces. The post-cementation crown elevation data was analyzed by one- and two-way ANOVA tests, and Tukey's HSD test. (2) The cements Vitremer, Fuji Duet and Dyract Cem, were tested in a similar fashion to Part 1, except activation of the loading apparatus was delayed. Three cement spaces (6, 29 and 52 microns) and three delay periods (60, 120 and 180 seconds) were investigated. Each cement was tested five times. The post-cementation crown elevation data was analyzed by one- and two-way ANOVA tests, and Tukey's HSD test.
  
  
  RESULTS
  The amount of cement space provided and the cement used significantly affected post-cementation crown elevation (P = 0.001). Where cementation was delayed, post-cementation crown elevation was significantly affected by both the cement used and the amount of cement space provided (P = 0.001). Delayed placement of Dyract Cem had no significant effect on post-cementation crown elevation (P = 0.01). Post-cementation crown elevation when Vitremer was used was significantly affected by both the amount of cement space and delayed placement (P = 0.01). A 180-second delay in placement of Vitremer resulted in significantly worse post-cementation crown elevation (P = 0.01). Seating was not possible 120 seconds after Fuji Duet had been mixed.
authors.affiliation: School of Dental Science, University of Melbourne, Victoria, Australia.
authors.forename: P R
authors.initials: PR
authors.lastname: Wilson
authors.forename: N R
authors.initials: NR
authors.lastname: Stankiewicz
mesh_terms: D000704:Analysis of Variance; D002484:Cementation / Q000379:methods; D020770:Compomers; D003188:Composite Resins; D003442:Crowns; D001840:Dental Bonding / Q000379:methods*; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D008422:Materials Testing; D008689:Methacrylates; D017640:Silicates; D013997:Time Factors; D015036:Zinc Phosphate Cement
chemical_list: D020770:Compomers; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C088486:Dyract; C113301:FujiPlus; D005899:Glass Ionomer Cements; D008689:Methacrylates; D017640:Silicates; C084550:Vitremer; D015036:Zinc Phosphate Cement; C086629:Phosphacap