Effect of simulated pulpal pressure on self-adhesive cements bonding to dentin.

Objectives: To evaluate the bonding effectiveness of self-adhesive luting cements to dentin in the presence of simulated hydrostatic intrapulpal pressure (PP).
Methods: Thirty composite overlays (Aelite All Purpose Body) were luted to deep-coronal dentin surfaces using four self-adhesive resin cements (Rely X Unicem, G-Cem, Multilink Sprint, Bis-Cem) and one total-etch system (Calibra). Half of the specimens resin cements were applied under a PP of 15 cm H2O. After storage in a moist condition for 1 month (37 degrees C, 100% relative humidity), specimens were sectioned into microtensile beams (1mm2) and stressed to failure with the microtensile bond strength test (microTBS). Data were statistically analyzed with Kruskal-Wallis ranking (p<0.05) and Mann-Whitney tests (p<0.001). The fracture pattern was evaluated under SEM.
Results: Bond strength of Calibra fell significantly when PP was applied during bonding (p<0.05). Rely X Unicem and Bis-Cem performed better under PP. No significant differences for Multilink Sprint and G-Cem bonded specimens were recorded with or without PP.
Significance: Simulated PP influences the adhesive performance of resinous cements. The predominance of acid-base reactions or radical polymerization may explain the different behavior of self-adhesive cements when changing substrate wetness. The application of constant intrapulpal perfusion should be considered when simulating luting procedures in vitro.