Shear Bond Strength on Dentin with Various Drying Techniques

Objectives: The aim of this study was to compare the bond strength of 5^th generation adhesive on dentin prepared with various drying techniques.

Methods: Forty-five caries-free human molar teeth were obtained for this study. Each tooth was embedded in clear acrylic and 2-3mm of the occlusal tooth surface were cut to expose the flat dentin surface. Dentin surfaces were polished down using 320-grit SiC paper. Samples were randomly divided into 6 groups (n=5). Three adhesives systems were tested with variation in drying technique. Adhesives: Prime&Bond NT (PBNT, Dentsply), Single Bond Plus (SBP, 3M ESPE) and Excite F (EF, Ivoclar).  Adhesives were applied according to manufacturer's instructions with exception of using the various drying modes: no stream air-dried (ND), air-dried with a gentle stream of air (GD), and dried with a strong stream of air (HD) prior to light curing for 10seconds. Z250 (3M ESPE) composite was filled into the bonding jig (Ultradent) and cured for 40seconds with LED light (DEMI, Kerr). After storage in de-ionized water for 24hours at 37⁰ C the occlusal shear bond strength was carried out using a universal testing machine (Instron 5566A, Norwood, MA) with a cross head speed of 1mm/min. Statistical analysis was done by one-way ANOVA. Statistical significance was predetermined at p<.05.

Results:

	PBNT			SBP			EF
	ND	GD	HD	ND	GD	HD	ND	GD	HD
Mean (MPa+SD)	11.12±2.76a	16.08±7.57a,b	22.06±5.18b	20.86±1.74a,b	16.45±3.43a,b	14.24±4.55a,b	12.48±10.59a	25.59±6.9b	13.86±6.13a

Conclusions: EF (alcohol based) adhesive yielded the highest bond strength when prepared with gentle air-dried technique.  PBNT (acetone based) adhesive yielded the highest bond strength when prepared with strong stream of air-dried technique. There was no statistical difference in bond strength on SBP (alcohol-water based) adhesive with various drying technique.