Microtensile dentin bond strength of recent adhesive systems

OBJECTIVE: Compare microtensile dentin bond strength (µTBS) of recently introduced adhesive systems to established dentin bonding agents.

METHODS: Occlusal dentin surfaces of 35 randomly selected non-carious, non-restored human third molars were flattened with the CNC Specimen Former (University of Iowa). Adhesives (Table) were applied according to manufacturers' recommendations and resin-based composite (Z100, 3M ESPE) was incrementally placed to approximately 5-mm in height with margins short of the DEJ. The composite build-ups were sectioned then trimmed into four cylindrical hourglass specimens per tooth (N = 140) with a cross-sectional area of 0.8 mm², 1 mm gage length and 0.6 mm radius of curvature with the CNC Specimen Former.  24 h later two specimens from each tooth were tensile tested in a passive gripping device (Dircks) at 1 mm/min, while the remaining two specimens were stored in PBS with 0.1% sodium azide at 37°C for long-term µTBS (6 months). Groups were analyzed by ANOVA with Tukey multiple comparisons method. Pre-test failures (PTFs) were excluded from the data set.

RESULTS:

Adhesive	Class (steps)	Dentin µTBS MPa (SD) [PTFs]		Lot #
Permaquik (Ultradent)	ER (3)	60.88 (10.86) [0]	a	#B27W;#B2X2H
All Bond 3 (Bisco)	ER (3)	57.99 (9.59) [0]	a	0700001619,20,21
PQ1 (Ultradent)	ER (2)	59.16 (20.04) [0]	a	#B2WCC
Peak SE (Ultradent)	SE (2)	61.02 (6.71) [0]	a	E118
Clearfil SE (Kuraray)	SE (2)	55.15 (1.92) [0]	a	#61836
Adper Easy Bond (3M ESPE)	SE (1)	44.94 (10.44) [0]	ab	#299001
Xeno V (Dentsply/Caulk)	SE (1)	20.70 (1.49) [7]	b	#0706000884

ER = etch-and-rinse; SE = self etch. Means with same letter not significantly different (p<0.05)

CONCLUSION: The self-etch 1-step adhesive had significantly weaker dentin µTBS at 1 day. Adhesives will be evaluated after 6 months storage for further discrimination between groups.

[This study was sponsored by Ultradent Products, Inc.]