Effect of pulpal pressure on bond strength of luting cements

Objectives: To examine the effect of pulpal pressure on the microtensile bond strength (MTBS) of resin luting cements to human dentin and the permeability of dentin surface pre-treated with an adhesive and a self-etching primer.

Methods: Dentin surfaces from forty-five extracted human third molars were abraded with 600-grit SiC paper. The teeth were divided into 3 groups for RelyX ARC (ARC; 3M ESPE), Panavia F (PF; Kuraray) and RelyX Unicem (UN; 3M ESPE). Cylindrical composite blocks were luted to dentin using the three cements in the presence or absence of pulpal pressure. The application of luting cements was performed under 0cm H₂O. For the pulpal pressure group, 20cm H₂O of hydrostatic pressure was applied for 10 min during the initial setting of cement. The bonded specimens were stored at 37°C for 24h and sectioned into 0.9x0.9mm beams for MTBS testing. Bond strength data were analysed using two-way ANOVA and Tukey multiple comparison test (p<0.05). A fluid-transport model was used to measure fluid permeability following application of Adper Single Bond 2 and ED primer.

Results: Microtensile bond strength (MPa, Mean ± SD)

Application of pulpal pressure significantly reduced MTBS of ARC and PF. Dentin surfaces treated with adhesive and primer were more permeable than smear layer-covered dentin. The MTBS of UN was significantly lower than ARC and PF regardless of the absence or presence of pulpal pressure.

Conclusion: Fluid transudation induced by pulpal pressure during the initial setting period deteriorated the bond quality of RelyX ARC and Panavia F. (Supported by HKU grant No:10207402.07840.08004.323.01)