RESUMO
The appearance of superficial and deep dentin differs and this may affect the bond strength of adhesive system. The aim of this study was to evaluate the shear bond strength of superficial and deep dentin using self-etch system. This in vitro and experimental study was done on 48 human extracted premolar teeth. After mechanical cleaning, they were disinfected with hypochlorite 5.25% and the roots mounted in acrylic resin. Teeth were divided into 4 groups: A, B, C, D. In A and B groups, buccal surface was reduced until dentino-enamel junction [DEJ]. In C and D groups, buccal surface was reduced 3 mm deeper than DEJ. We used 2 groups of setf-etch systems: Prompt-Lpop and Prime and Bond NT. Prompt-Lpop was used in A and C groups, and Prime and Bond NT was used in B and D, according to their manufacturers' instructions. Pieces of composite with 1.5 mm diameter and 2 mm height were bonded on treated buccal surface of teeth. Finally specimens were loaded to failure in a universal testing machine at a crosshead speed of 1mm/min. The two-way analysis of variance was used for comparing the shear bond strength among the various groups. The mean value of shear bond strength of Prompt-Lpop in superficial dentin was 26.42 +/- 3.40 MPa and in deep dentin was 11.83 +/- 2.62, and of Prime and Bond NT in superfacial dentin was 24.33 +/- 4.70 MPa and in deep dentin was 12.91 +/- 2.21. The mean value of shear bond strength of superficial dentin was 25.37 +/- 4.10 MPa and deep dentin was 12.35 +/- 2.42 Mpa. Statistical analysis of the data showed that there was not a significant difference in shear bond strength between Prompt-Lpop and Prime and Bond NT [P=0.613]. There was a statistically significant difference in shear bond strength between superficial and deep dentin in each self etch system separately. According to data analysis conservative cavity preparation with less depth is recommended for efficient restoration when using self etchant dentin adhesive systems