Improving shear bond strength of metallic brackets after whitening

Abstract

Objective: To evaluate a protocol for bonding metallic brackets after bleaching with hydrogen peroxide (HP). Methods: 60 extracted maxillary premolar were randomly divided into an unbleached control group and two groups bleached with a solution of 35% hydrogen peroxide prior to bonding. The teeth in one of the treated groups were bonded immediately after bleaching; while the other group was treated with 10% sodium ascorbate immediately after bleaching and before bonding. The teeth in all groups were stored in an artificial saliva solution for 7 days after bonding. The shear bond strength data was measured in megapascals (MPa) and the fail attempts were verified. The significance level was established at p< 0.05. Results: The unbleached group, in which brackets were bonded to untreated enamel, had the highest bond strength values (11.0 ± 5.7MPa) in comparison to the bleached group (7.14 ± 40MPa), in which brackets were bonded to recently bleached enamel. Slightly improved bond strength was observed in the antioxidant group (8.13 ± 5.4MPa), in which the teeth were bleached and then the antioxidant was applied to the teeth before bonding. Unbleached and bleached groups showed statistically significant difference for shear bond strength (p=0.03) and load strength (p=0.03); no significant differences were noted between unbleached and antioxidant groups (p=0.52). Conclusion: The antioxidant treatment applied immediately after bleaching was effective in reversing the reduction in shear bond strength of brackets after tooth bleaching.

Efectividad del blanqueamiento dental en pacientes con tratamiento de ortodoncia fija activa: Una revisión narrativa

“…With respect to the different materials used to decrease CR during and after clearance, several studies show that antioxidant treatment and other materials used after clearance are effective in increasing the shear resistance of brackets ( 21,27,34,35 ). The presence of a bracket attached to the tooth acts as a barrier to the penetration of peroxide, which affects the homogeneity of color in the samples of this research ( 24 ).…”

“…Usually, the dental whitening procedure is performed after orthodontic treatment. 7 However, in some circumstances the motivation of the patient in wanting to present a smile aligned at the same time with teeth clarified, led to the report of in vivo and in vitro studies, which show that dental whitening during an active fixed orthodontic treatment is an apparently non-harmful and effective aesthetic alternative ( 7,8,21 ).…”

“…One study evaluated a protocol for joining metal brackets after whitening with hydrogen peroxide, and concluded that the antioxidant treatment applied immediately after whitening was effective in reversing the reduction in shear resistance of the brackets after teeth whitening, in this case they used 10% sodium ascorbate, which reversed the decrease in shear resistance ( 21,27 ). Likewise, another study demonstrated the reduction of the shear resistance of composite resin adhered to the enamel followed by the clearance with hydrogen peroxide to 35%, in addition to stating that 10% of sodium ascorbate increased the bonding force after clearance with respect to ceramic brackets and almost the same result for metal brackets ( 29 ).…”

Can antioxidant treatment replace delay in bracket bonding? An in vitro study

“…Fortunately, the reduction in SBS appears to be transient, and a recovery period after bleaching, ranging from 24 h to 2 weeks or more, has been recommended [ 5 – 8 ]. Some strategies for avoiding delays in bonding involve treating enamel with alcohol, adhesives with organic solvents, or removing the superficial enamel layer [ 9 – 11 ]. Moreover, the application of different antioxidant agents after HP bleaching instantaneously boosts SBS.…”

Does the application of whitening dentifrices during at-home bleaching affect the bond strength of resin composite to dentin?

“…Several strategies have been suggested to neutralize and reverse the effects of bleaching agents on bond strength such as delaying the restorative procedures up to 2 weeks after whitening [17][18][19] or treatment of the tooth surface with chemicals such as sodium ascorbate (a potent antioxidant), catalase, ethanol or water to dissociate residual peroxides and oxygen free radicals from the substrate [13,[20][21][22][23]. Another option to enhance the bond strength may be the increase in the polymerization time of adhesive systems.…”