Self-etching Enamel bond strength: Effect of Application method

Objectives: The purpose of this study was to determine the effect of different self-etching primer application methods on the enamel shear bond strength for a self-etching bonding agent. Methods: 50 Recently extracted human third molar teeth were cleaned, prepared to expose occlusal enamel and embedded in acrylic resin in stainless steel rings. For each of the test groups 10 Composite stubs were bonded to the enamel surface using the specific bonding agent and application method. These bonds were stressed to failure using an Instron testing machine. Application methods evaluated: 1. Apply 20 seconds , no agitation 2. Apply 20 seconds, no agitation plus 10 seconds fresh product , no agitation. 3. 10 seconds agitation, fresh product, further 10 seconds agitation 4. 20 seconds constant agitation 5. Apply 10 seconds, constant agitation Results: Although the highest mean shear bond strength (30.22 MPa) was obtained with group 3, no statistical difference was found for any of the groups. Conclusion: Agitation seems to increase the shear bond strength but the standard deviation subsequently increases. The most predictable results (lowest standard deviation) was obtained using the manufacturers recommended application protocol.