An in vitro experimental study was carried out with the objective to compare the friction in aesthetic and metallic brackets after prophylaxis with sodium bicarbonate jet during sliding mechanics.

Aesthetic monocrystalline (n=24) and polycrystalline (n=24) and metallic brackets (n=24) were used. Each group of brackets was divided into two groups, as follows: the first group received prophylaxis with a bicarbonate jet, while the second group did not. An acrylic plate was attached to the base fixature of the Instron 4411 universal testing machine, simulating the retraction movement of the canine during sliding mechanics. The bracket was pulled at a speed of 0.5mm/minute over a distance of 0.5mm. The data were analysed by analysis of variance (ANOVA) and Tukey test.

After the sodium bicarbonate jet, conventional metal brackets showed less friction (P<0.05). While the aesthetic brackets did not show significant difference in friction between the exposed and non-exposed groups with the sodium bicarbonate jet (P>0.05), the polycrystalline brackets showed greater friction when compared to the other groups of brackets.

It was concluded that prophylaxis with sodium bicarbonate jet did not influence the resistance to friction in aesthetic brackets; however, metal brackets showed a significant decrease in friction after prophylaxis with sodium bicarbonate jet. Our results suggest that the abrasion of the sodium bicarbonate particles can cause micromorphological changes, which may influence the friction; however, studies with scanning electron microscopy are necessary.