RESUMEN
AIM: this study evaluated the bond strength of an adhesive system to human dentin prepared with reused diamond burs. MATERIAL AND METHODS: five molars (G1) were prepared in a standardized way with five diamond burs. Flat deep dentin surfaces were etched, received adhesive and received composite build-ups. The same burs were cleaned and reused on another five teeth groups (G2 until G8). After 24-hours storage and thermocycling, 50 dentin-resin sticks per group were obtained and subjected to microtensile bond strength test (µTBS). RESULTS: analysis of variance (ANOVA) and Tukey test were applied to identify differences between groups (p<0.05). The reuse of a diamond bur for more than two preparations resulted in significantly lower µTBS values (G1 = G2 > G3 = G4 = G5 = G6 = G7 = G8). CONCLUSION: Reuse of diamond burs interfered on adhesion between dentin and resin.