Evaluation of the Effect of Four Surface Conditioning Methods on the Shear Bond Strength of Metal Bracket to Porcelain Surface

Abstract

Objective: This study evaluated the effect of superpulse CO 2 laser irradiation and deglazing of porcelain surfaces on the shear bond strength (SBS) of metal orthodontic brackets, and compared it with two conventional etching techniques. Methods: Forty-eight Feldspathic porcelain fused to metal specimens embedded in cylindrical acrylic resin tubes were fabricated, and all the specimens were divided into four groups. In Group 1, the specimens were roughened with a diamond bur and etched with hydrofluoric acid (HFA) gel for 4 min. In Group 2, the specimens were roughened with a bur and irradiated by a CO 2 laser with a 2 W power setting for 20 sec. In Group 3, the specimens were only irradiated by a CO 2 laser. In Group 4, the porcelain surface was sandblasted with 50 lm aluminum oxide. Before bonding, the bracket silane was applied on the porcelain surfaces. SBS was evaluated by a Universal testing machine (Zwickroll, Germany). The remaining adhesive after the bond failure was evaluated using an adhesive remnant index (ARI). Statistical analysis was conducted by analysis of variance (ANOVA), Tukey, and Kruskal-Wallis tests. Results: ANOVA revealed significant differences in SBS among the four groups ( p < 0.001). Group 1 demonstrated significantly higher bond strength (13.13 -2.47) when compared with the other groups. Group 2 showed higher bond strength (9.60 -1.91) when compared with group 4 (6.40 -1.67) ( p = 0.016). Group 1 displayed the highest ARI scores among the groups. Conclusions: Deglazing combined with HFA etching produced the highest bond strength, but CO 2 laser irradiation provided adequate bond strength and allowed for elimination of the HFA step. Deglazing is not recommended as a preliminary step before CO 2 laser conditioning.

The Effect of Fractional CO2 Laser Irradiation on Shear Bond Strength of Resin Cement to Feldspathic Porcelain

“…A recent study 12 found that fractional CO2 laser has better performance when used on deglazed than glazed feldspathic porcelain for bonding metal orthodontic brackets. However, Zarif Najafi et al 26 concluded that deglazing is not a mandatory step before application of CO2 laser for surface preparation of feldspathic porcelain. In the present study, the use of HF acid provided bond strength value that was significantly greater than that of the air-abraded and laser-treated specimens.…”

Influence of hydrofluoric acid etching time and concentration on shear bond strength of metal brackets to ceramic surfaces

“…Hydrofluoric acid is cited as being a ceramic surface conditioner because of its capacity to promote the morphological changes necessary for bonding [1][2][3][4][5] . The growing need for esthetic rehabilitation has raised the demand for orthodontic treatment and increasingly improved alignment of teeth.…”

“…The literature has suggested surface treatment options for the purpose of promoting enamel surface roughness before bracket bonding 1,6 . Roughness may be achieved by mechanical means using diamond tips or airborne particle abrasion with aluminum oxide particles 1,6 .…”

“…The literature has suggested surface treatment options for the purpose of promoting enamel surface roughness before bracket bonding 1,6 . Roughness may be achieved by mechanical means using diamond tips or airborne particle abrasion with aluminum oxide particles 1,6 . However, the literature has demonstrated crack propagation within the ceramic, and consequent weakening of the part, making it unfeasible to use this form of roughening 7 .…”

“…Hydrofluoric acid has been shown to be an effective option for preparing surfaces that will receive metal orthodontic accessories [1][2][3][4][5] , because it promotes dissolution of the vitreous portion of ceramic. This leads to change in its morphology by creating irregularities that will help the wetting proposed by saline, and consequently, a more effective bond 4,5,9 , intensifying the bond strength 10 .…”