RESUMO
OBJECTIVES: The purpose of this study was to evaluate, in vitro, the tensile bond strength of the Single Bond (3M) adhesive system placed over dentin surfaces treated with air turbine, Er:YAG laser without contact and in focused or air abrasion. SUMMARY BACKGROUND DATA: The use of dentin adhesives is a well-established clinical routine among the dentists. However, there have been few reports comparing the influence of the Er:YAG laser, air abrasion, and air turbine on the Single Bond tensile bond strength of adhesives systems to dentin fact that could influence which tools dentists select for use in cavity preparations. METHODS: Twenty-three extracted retained human molars were used in this study. The coronal portion was divided in two parts and fixed in acrylic resin; the occlusal surface was abraded to a 2-mm width with a mechanic lathe until the dentin surface was completely exposed. The dental portions were divided into three groups of 15 each and treated with Er:YAG laser, air abrasion, or air turbine. A 3 mm hole in the center of each tooth was marked off using contact paper. Single Bond (3M) adhesive system was applied after acid phosphoric at 35% application for 15 sec over dentin surfaces. A resin composite cone was built into the delimited area to accomplish the tensile bond strength test on the EMIC universal test machine. The specimens were then evaluated by stereoscopy to determine the type of failures into the dentin-adhesive-resin composite surface. RESULTS: The tensile test was performed using the universal testing machine EMIC DL-2000 at a cross-head speed of 0.5 mm/min. The average results were: air turbine (17.52 MPa), Er:YAG laser (16.65 MPa) and air abrasion (15.83 MPa). Statistical treatment by ANOVA and Tukey's test (p < 0.01) showed no significant differences between the groups tested. The tensile bond strength test to the dentin showed no significant difference among the three groups when the Single Bond was used after the 35% phosphoric-acid conditioning. The stereoscopy showed a predominant adhesive failure in all groups. CONCLUSION: These results suggest that Single Bond tensile bond strength is the same as dentin prepared by Er:YAG laser, air abrasion, or air turbine.