Comparison of Two Methods for Shear Bond Strength Testing

Objectives: The purpose of this study was to compare shear bond strengths of a single adhesive system determined using the UltraTester (Ultradent, Inc.) device and a more traditional testing device (Instron model 4411, crosshead speed 1 mm/min).  

Methods: Human and bovine enamel and dentin were polished to 600-grit.  Surfaces were treated using Clearfil SE Bond self-etch primer and adhesive.  Flowable composite was applied to the treated tooth surfaces using the standard Ultradent specimen former.  Bonded specimens were stored in water for 24 hours at 37°C, and shear bond strength testing was done using either the Instron or the UltraTester.  Specimen number = 6 for each group as defined by the three independent variables: (type of tooth, substrate, and test device).  Data were analyzed using three-way analysis of variance (ANOVA; alpha = .05). 

Results:  Mean SBS values (MPa ±SD) are summarized in the table.  None of the independent variables had a statistically significant effect on bond strength.

Substrate	Type	UltraTester	Instron
Enamel	Human	27.3 (8.1)	26.0 (5.1)
	Bovine	29.1 (6.9)	29.6 (6.7)
Dentin	Human	29.1 (8.0)	27.0 (7.6)
	Bovine	26.5 (7.6)	31.5 (5.7)

Conclusions: Shear bond strengths determined by the two different testing methods were similar regardless of tooth and substrate type.