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Phosphoric acid etching has been widely used to achieve a strong andlong lasting mechanical bonding between composite resin restorationand tooth structure. The bond strength between the composite resinrestoration and the enamel of permanent teeth can be measured by theshear bond strength of the composite resin restoration. The aim of thisstudy was to evaluate the bond strength between the enamel ofpermanent teeth and the composite resin restoration by measuring theshear bond strength after different durations of etching. In total 27premolar teeth were divided into 3 groups where the enamel of thebuccal surface was etched with 37% phosphoric acid for 5″, 15″, and25″ before placing the composite resin restoration. After keeping theteeth inside an incubator for 24 hours, the shear bond strength wasmeasured using a universal testing machine Shimazu AG-5000 at acrosshead speed of 0.5 mm/min. ANOVA was used for statisticalanalysis of the results, with p<0.05 assumed to imply significance.The mean shear bond strength after etching for 5″, 15″, and 25″ was16.1 MPa, 17.3 MPa and 19.0 MPa, respectively. The results of ANOVA showed significant difference between the 3 groups. However, subsequent Tukey test showed significant difference between 5″ and 25″ of etching (p<0.05), but no significant difference between between the 5″ and 15″ groups nor between the 15″ and 25″ groups (p>0.05). Conclusion: Shear bond strength of the composite resin on the permanent teeth enamel increased with increasing etching time. Significant difference was showed between 5″ and 25″ of etching time. |
