G H Johnson1, X Lepe, D J Bales. 1. Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, USA.
Abstract
STATEMENT OF PROBLEM: A previous study showed that a resin sealer decreased casting retention with zinc phosphate cement. PURPOSE: This study determined whether a nonresin sealer applied to prepared dentin affected the retention of cemented castings. MATERIAL AND METHODS: Extracted molars were prepared with a flat occlusal, 20-degree taper and 4 mm axial length. The axial surface area of each preparation was determined and samples were distributed to achieve equivalent groups. Gluma Desensitizer sealer was used to seal the dentin before provisionalization and again before crown cementation. An Olympia alloy casting was produced for each preparation and cemented with a seating force of 20 Kg with either Mizzy's zinc phosphate, Ketac-Cem glass ionomer, or Resinomer material in combination with One Step adhesive. Castings were thermocycled, then removed along the path of insertion with an Instron testing machine. A two-factor analysis of variance was used with alpha = 0.05 and n = 9.10. RESULTS: Mean dislodgment stresses for unsealed and sealed conditions were 6.3 and 6.4 MPa for zinc phosphate, 9.1 and 10.1 MPa for glass ionomer, and 12.1 and 12.6 MPa for the resin cement. The means for the three cements were statistically different (p < 0.001). The effect of sealer (p = 0.369) and cross product interactions (p = 0.820) were not significant. CONCLUSIONS: The use of the glutaraldehyde-based system as a desensitizing treatment for prepared teeth had no effect on crown retention for any of the three cements evaluated and the modified resin cement produced the highest mean dislodgment stress that exceeded the strength of the tooth.
STATEMENT OF PROBLEM: A previous study showed that a resin sealer decreased casting retention with zinc phosphate cement. PURPOSE: This study determined whether a nonresin sealer applied to prepared dentin affected the retention of cemented castings. MATERIAL AND METHODS: Extracted molars were prepared with a flat occlusal, 20-degree taper and 4 mm axial length. The axial surface area of each preparation was determined and samples were distributed to achieve equivalent groups. Gluma Desensitizer sealer was used to seal the dentin before provisionalization and again before crown cementation. An Olympia alloy casting was produced for each preparation and cemented with a seating force of 20 Kg with either Mizzy's zinc phosphate, Ketac-Cem glass ionomer, or Resinomer material in combination with One Step adhesive. Castings were thermocycled, then removed along the path of insertion with an Instron testing machine. A two-factor analysis of variance was used with alpha = 0.05 and n = 9.10. RESULTS: Mean dislodgment stresses for unsealed and sealed conditions were 6.3 and 6.4 MPa for zinc phosphate, 9.1 and 10.1 MPa for glass ionomer, and 12.1 and 12.6 MPa for the resin cement. The means for the three cements were statistically different (p < 0.001). The effect of sealer (p = 0.369) and cross product interactions (p = 0.820) were not significant. CONCLUSIONS: The use of the glutaraldehyde-based system as a desensitizing treatment for prepared teeth had no effect on crown retention for any of the three cements evaluated and the modified resin cement produced the highest mean dislodgment stress that exceeded the strength of the tooth.