In-Vitro Microtensile Bond Strength of Four Self-Etch Adhesives

Objectives: The purpose of this in-vitro pilot study was to compare the dentin microtensile bond strength of four self-etch adhesive systems. Methods: After IRB approval, human 3^rd molars were randomly distributed into four treatment groups: Clearfil-SE (two-step, water-based, Kuraray Medical^TM), An experimental Silorane adhesive (two-step, water-based, subsequently marketed as 3M^TM ESPE^TM LS System Adhesive), Adper^TM EasyBond (one-step, water-based, 3M^TM ESPE^TM), and Adper^TM Scotchbond^TMSE (two-step, water-based, 3M^TM ESPE^TM).  Each tooth had its enamel removed using 60, 240 and 320 grit wet sandpaper until only dentin was visible.  After adhesive placement 3M^TM ESPE^TM Flitek^TM Z250 Universal Restorative was applied/cured with a quartz halogen light in four 1.0 mm increments.  Manufacturer's directions were followed.  For the experimental adhesive a Silorane experimental resin composite was used instead (subsequently marketed as 3M^TM ESPE^TM Filtek^TM LS).  Teeth were sectioned immediately after being restored to obtain rectangular specimens with a surface area ~0.5 mm². Samples were tested on a Bisco Microtensile Tester until failure at a crosshead speed of 2.0 mm/min. Light Microscopy (10X) was used to characterize modes of failure as either adhesive or cohesive.

Results:

Material	N	Mean ± (Std Dev) in MPa	Cohesive Failures	Debonds during specimen preparation
Clearfil SE	51	59.2 (15.0)	21	0
Experimental Silorane	49	44.3 (9.9)	4	0
Adper Easy Bond	49	52.8 (16.9)	2	2
Adper Scotchbond SE	45	39.1 (17.2)	0	13

One-way ANOVA found a statistically significant difference between adhesives (p≤ 0.001). Post-hoc testing using the Bonferroni procedure showed that both ClearFil-SE and AdperEasyBond had significantly (p<0.05) higher bond strengths than Adper ScotchbondSE and the experimental Silorane. Groups differed significantly in the number of debonds c²[3,N=15]=31.3, p≤0.001. Groups differed significantly in the number of cohesive failures c²[3,N=27]=41.3, p≤0.001.  Conclusion: Clearfil-SE and AdperEasyBond outperformed the other adhesives in bond strength.  Supported by USPHS Grant K23-DE016324.   purkj@umkc.edu