Shear Bond Strength of Selective-etch Adhesives on Cut/Uncut Enamel

Objectives: To compare shear bond strength of 7^th generation adhesive systems on cut and uncut enamel prepared with selective-etch or preferential etch technique.

Methods: �One-hundred extracted caries-free human teeth were obtained for this study. Each tooth was embedded in acrylic resin. The samples were randomly divided into ten groups (n=10, five groups cut (C), five uncut (U) ). Cut enamel surfaces were prepared using SiC paper up to 600 grit (Ecomet3, Buehler). �Uncut were embedded with their buccal surface exposed. �Three adhesive systems were tested with variations in etching: Prime&Bond NT (PBNT, Dentsply), Adper Easy Bond (AEB, 3M ESPE) and experimental adhesive EXL-759 (EXL, 3M ESPE).� Adhesives were applied according to manufacturers' instructions with exceptions of using the self etch mode (SE) or pre-treating with etch (PE). Z250 (3M ESPE) composite was filled into a bonding jig (Ultradent) and cured for 40 seconds with a halogen light (Epilar 2500). After storage in de-ionized water for 24 hours at 37�C, the shear bond strength �was carried out using a universal testing machine (Instron 5566A, Norwood, MA) with a cross head speed at 1mm/min. Statistical analysis was done by one-way ANOVA, with post-hoc analysis conducted via Fisher LSD. Significance was predetermine at p<0.05.

Results:

	PBNT, C, PE	PBNT, U, PE	AEB, C, PE	AEB, U, PE	AEB, C, SE	AEB, U, SE	EXP, C, PE	EXP, U, PE	EXP, C, SE	EXP, U, SE
Mean (MPA) SD	31.93 �4.99	32.03 �9.26	35.18 �4.03	31.10 �7.61	26.56 �5.83	26.06 �11.20	34.11 �5.68	41.65 �7.11	23.51 �6.47	36.86 �11.81
Statistic group comparison	a,d	a,e	b,c,d,e,h	a,c	a,c,f	a,c	b,c,d,e	b,f,h	a,c,d	b,c,d,e,g

Conclusions: �In terms of mean values, EXP with selective-etch has higher bond strength than AEB self-etch on both cut and uncut enamel. Uncut enamel yields significantly higher bond strength compared with the cut enamel on EXP self-etch.