Bond Strength of HEMA-free And HEMA-containing Adhesives Under Pulpal Pressure

Objectives: To evaluate the effect of simulated pulpal pressure (PP) on initial bond strength of one-stsep self-etch adhesives with different smear layer preparation. Methods: Flat coronal dentin surfaces were obtained from extracted molar teeth .Smear layers were created by grinding with either #180 or #600 grit paper. A HEMA-free one-step self-etch adhesive, Xeno V (XV; Denstply,Germany) and a HEMA-containing adhesive, Tokuyama Bond Force (TBF;Tokuyama Corporation,Japan) were applied to the dentin surfaces according to the manufacturer's instructions under a hydrostatic pressure of 0 or 15 cmH₂O. Specimens bonded under 0 cmH₂0 pressure was served as a control group.  After coronal build up with composite resin (CLEARFIL AP-X), the specimens were stored in water at 37⁰C for 24 hour. Bond strength to dentin were determined using microtensile bond (µTBS) testing and all data were statistically analyzed using one-way ANOVA (materials and experimental conditions) and additional t-test. Results: The bond strength values (µTBS) results table are as follows.

MATERIALS	EXPERIMENTAL CONDITION
	SiC PAPERS (grit size)	PULPAL PRESSURE
		0 cm H20	15cm H20
TOKUYAMA BOND FORCE	#180	33.4±9.7Ab	31.2±8.8 Ab
	#600	39.6+8.3Ab	33.3_6.8Ab
XENO V	#180	29.7±6.8Ab	21.6±8.9Bc
	# 600	39.0±9.5Ac	34.2±10.5Ad

Values are in MPaħS.D. n=8 (per group).  Groups identified by the same capital and small superscript letter in each row and column are not significantly different (p>0.05). 

Conclusions:  .

The 15 cmH₂0 pulpal pressure (PP) had decreased the bond strength (BS) significantly of the HEMA-free material, XV in  the  thicker smear layer (#180-grit prepared).