In vitro evaluation of dental bonding agents using shear and vibrational methods

Objective: To determine the suitability of two mechanical test methods for the in vitro evaluation of dental bonding agents. Methods: The first method was the Iosipescu shear test in which a pure shear stress is induced in a notched beam sample, and the second was a multilayer vibrating reed test in which the effectiveness of bonding could be assessed by the magnitude of relative elastic modulus and mechanical damping factors. The tests were applied to bonded samples of high-copper amalgam, gallium alloy and composite resin with two different types of adhesive. Representative data is presented to show the capabilities of the test methods. Results: Both methods were shown to generate more consistent data with lower scatter than that usually reported in this field. Each may be used to provide information of clinical relevance. Conclusion: With further development, these test methods could make a useful contribution to the assessment of dental bonding agents.