Air-powder polishing on self-ligating brackets after clinical use: effects on debris levels

Comparison of friction of metallic and ceramic brackets during sliding mechanics after prophylaxis with sodium bicarbonate jet: An in vitro study

OBJECTIVE

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.

MATERIAL AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Prophylaxis protocols and their impact on bracket friction force

OBJECTIVE

To evaluate the effect of two different prophylaxis protocols on the friction force in sliding mechanics during in vivo leveling and alignment.

MATERIALS AND METHODS

The sample comprised 48 hemi-arches divided into three groups according to the prophylactic protocol adopted. Group 1 consisted of patients undergoing prophylaxis with sodium bicarbonate, group 2 consisted of patients submitted to prophylaxis with glycine, and group 3 consisted of patients without prophylaxis, as a control. All patients received hygiene instructions and, with the exception of group 3, prophylaxis was performed monthly. After 10 months, the brackets were removed from the oral cavity and submitted to friction force tests and qualitative analysis by scanning electron microscopy. Analysis of variance followed by Tukey tests was performed for intergroup comparison regarding the friction force.

RESULTS

The experimental groups presented significantly smaller friction forces than the group without prophylaxis. Accordingly, qualitative analysis showed greater debris accumulation in the group without the prophylactic procedures.

CONCLUSIONS

Prophylactic blasting with sodium bicarbonate or glycine can significantly prevent an increase of the friction force during sliding mechanics.