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Influence of tooth surface roughness and type of cement on retention of complete cast crowns
M F Ayad1, S F Rosenstiel, M Salama
1Section of Restorative and Prosthetic Dentistry, School of Dentistry, College of Dentistry, Ohio State University, Columbus, USA.
Statement Of Problem:
Bond strength of luting cements to dentin is a critical consideration for success of cast restorations.
Purpose Of Study:
This study determined the relationship between surface characteristics of teeth prepared for complete cast crowns and retention of respective cemented restorations.
Material And Methods:
Ninety artificial crowns were cast for standardized complete crown tooth preparations accomplished with the use of a milling machine on extracted human teeth. Diamond, tungsten carbide finishing, and cross-cut carbide burs of similar shape were used. The crowns in each group were randomly subdivided into three subgroups of 10 for the three luting cements selected for this study: zinc phosphate cement (Fleck's), glass ionomer cement (Ketac-Cem), and adhesive resin cement (Panavia-EX). Retention was evaluated by measuring the tensile load required to dislodge the artificial crowns from tooth preparations with an Instron testing machine.
Results:
Analysis of forces with parametric analysis of variance and Tukey's Studentized Range (HSD) disclosed a statistically significant difference for both luting cement and finishing burs (p < 0.001). A statistically significant interaction effect (p < 0.001) was also found. The greatest retention value (372.9 N) was for tooth preparations refined with carbide burs and cemented with Panavia-EX cement. However, the least retention value (201.6 N) was for tooth preparations completed with finishing burs and luted with zinc phosphate cement.
Conclusions:
Significant differences were found among all three cements for finishing burs. However, there was a difference only between Panavia-EX cement and the other two cements for tungsten carbide burs. For diamond rotary instruments, zinc phosphate cement was significantly different from glass ionomer and Panavia-EX cements.