Effects of Er, Cr: YSGG Laser on Shear Bond Strength of the Orthodontic Brackets for 5 and 10 Seconds: An In Vitro Study

Abstract

Objectives. The study designed to compare the effect of erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr: YSGG) laser at different power outputs and short periods of time (5 and 10 s) and acid etching on the shear bond strength (SBS) and failure mode of metallic orthodontic brackets. Material and methods. A total of sixty-nine human premolars extracted for orthodontic purposes were used. 60 teeth were randomly assigned to one of the five treatment groups. (n = 12): group 1: 37% phosphoric acid etching and groups 2–5: the enamel surface irradiated by the Er, Cr: YSGG laser operated at different power outputs (1 W, 1.5 W, 2 W, and 2.5 W), each laser group was divided into two subgroups (n = 6) according to exposure time (5 s and 10 s). Nine teeth were not subjected to SBS testing but were prepared for scanning electron microscopy (SEM). The nonparametric Kruskal–Wallis test was used to evaluate the data; the SBS and adhesive remanent index (ADI) were evaluated. Results. The mean SBS for all laser groups and the acid-etched group were comparable, with no significant differences except for the 1 W group for 5 and 10 s and the 1.5 W group for 5 s. For the ARI scores, no statistically significant difference was found among the groups ( P = 0.059 ), and the majority of the samples had ARI type 2 or 3. Conclusion. The laser irradiation at 2 and 2.5 W for 5 s was similar to that produced by acid etching, whereas the laser irradiation at 2 and 2.5 W at 10 s was higher compared with that obtained with acid etching and adequate to etch the enamel.

Effect of Over-the-counter Whitening Toothpaste and Mouthwash in Orthodontics: A Literature Review

“…Another important factor that intervenes is the morphology of the base of the brackets and the structural characteristics of the enamel. 28 , 29 In this regard, a third study found no differences in the morphology of the enamel for whitening toothpaste, 8 where the same brackets from the two previous studies were used, but evaluating human enamel with a control medium such as saliva that may have some effect on enamel remineralization. 28 …”

“…Adhesive remnant analysis is performed to reinforce the evaluation of resistance to shear forces, using the adhesive remnant index (ARI). 29 In two included studies, whitening toothpastes with high abrasiveness frequently had ARI values ​​of 2 and 3, 18 , 20 that is, at least half of the adhesive cement remains in the bovine enamel after removal. An important factor to consider is the use of phosphoric acid in conventional adhesion systems, which increases the adhesive remnant in the enamel, 29 as occurred in the two included studies.…”

“… 29 In two included studies, whitening toothpastes with high abrasiveness frequently had ARI values ​​of 2 and 3, 18 , 20 that is, at least half of the adhesive cement remains in the bovine enamel after removal. An important factor to consider is the use of phosphoric acid in conventional adhesion systems, which increases the adhesive remnant in the enamel, 29 as occurred in the two included studies. Another important factor that intervenes is the morphology of the base of the brackets and the structural characteristics of the enamel.…”

An In-Vitro Analysis of the Surface Treatment of Orthodontic Bracket Bases With Er,Cr:YSGG Laser and Its Effect on Shear Bond Strength

“…Thus, the wattage of the laser irradiation also played a crucial role in altering the bond strength of the brackets. Bhagwan et al discovered that laser irradiation at a power of 2 and 2.5 W for 10 seconds was more potent than acid etching and sufficient to etch enamel [ 20 ]. This result was in line with research by Usmez and Aykent [ 21 ] and Berk et al [ 22 ], who compared the bonding efficiency using the Er,Cr:YSGG laser with a power of 1 Watt for a time period of 15 seconds and had discovered that it was substantially less than conventional acid etching [ 21 , 22 ].…”