Efficacy of microtensile versus microshear bond testing for evaluation of bond strength of dental adhesive systems to enamel.
OBJECTIVE
The aim of the study was to evaluate the efficacy of the microtensile bond test (microTBS) and the microshear bond test (microSBS) in ranking four dental adhesives according to bond strength to enamel and identify the modes of failure involved.


METHODS
Forty-four caries-free human molars were randomly assigned to one of two bond strength testing methods: 20 teeth were used for microTBS test and 24 teeth for microSBS test. Flat enamel surfaces were created by wet grinding. Four adhesive systems were applied to the ground enamel surfaces; a two-step self-etch (Clearfil SE Bond, SEB), two all-in-one self-etch (Adper Prompt L-Pop, APL; Hybrid Bond, HB) and a two-step etch-and-rinse (Adper Single Bond, ASB). Resin composite (Z100) was applied over the adhesive. The microTBS and microSBS were determined after 24h of storage in water at 37 degrees C. The mode of failure was determined by light microscope and SEM. Data was analyzed with ANOVA, Tukey's and Chi-square tests.


RESULTS
microTBS test ranked the adhesives as follows: SEB=ASB=APL>HB, while microSBS test ranked the adhesives as follows: ASB>SEB=APL>HB. The highest percentage failure mode with microTBS testing was cohesive in enamel or at the DEJ: SEB (95%), APL (65%) and ASB (65%). As for HB, adhesive failure (95%) was the common finding. The predominant failure mode in case of the microSBS was adhesive (APL 50%, SEB 58.3%, ASB 75% and HB 91.7%).


CONCLUSIONS
Ranking appears to be test-dependant and microSBS test appears to be more accurate in differentiating among the stronger adhesives.
El Zohairy
Ahmed A
AA
Department of Operative Dentistry, Faculty of Dentistry, University of Cairo, 1 Saraya El Manial St., Manial, Gizeh 11211, Cairo, Egypt.
Saber
Mohamed H
MH
Abdalla
Ali I
AI
Feilzer
Albert J
AJ
D000704:Analysis of Variance; D016009:Chi-Square Distribution; D001840:Dental Bonding; D003743:Dental Enamel; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing / Q000379:methods; D019279:Resin Cements; D033081:Shear Strength; D018709:Statistics, Nonparametric; D013718:Tensile Strength
D019279:Resin Cements