Effects of Antioxidants on the Shear Bond Strength of Orthodontic Brackets Bonded to Bleached Human Teeth: An In Vitro Study

Abstract

Aim:The aim of this study was to evaluate the effects of different concentrations of sodium ascorbate (SA), green tea (GT), and chamomile (CM) on the shear bond strength (SBS) of metal orthodontic brackets bonded to teeth bleached with 40% hydrogen peroxide (HP). Materials and methods: Ninety-four sound premolars were divided into eight groups: group I (control + no bleaching), group II (bleaching + immediate bonding), group III (bleaching + 10% SA), group IV (bleaching + 35% SA), group V (bleaching + 0.5% GT), group VI (bleaching + 1% GT), group VII (bleaching + 0.5% CM), and group VIII (bleaching + 1% CM). In groups III-VIII, teeth were treated with the antioxidants for 10 minutes after bleaching with 40% HP, but before bonding. All the specimens were bonded with the resilience adhesive, and the SBS was tested with a universal testing machine (Instron 5965). The cross-head speed to break the bond was 1 mm/minute. The adhesive remnant index (ARI) was tested under 50× magnification. One-way analysis of variance, Tukey's post hoc, and Chi-squared tests were used for analysis (p ≤ 0.05). Results: The differences in SBS among the eight tested groups were highly significant (p < 0.001). Comparison of the eight groups using Tukey's post hoc test revealed significantly lower SBS (p < 0.001) in test groups II, III, IV, and VIII than in group I. Adhesive remnant index scores showed significant intergroup differences (p = 0.005). Most groups had a failure score of 1 (<50% of the bonding material adhering to the tooth), whereas groups II and VIII showed a failure score of 0 (no material adhering to the tooth). Conclusion: Bond strength can be enhanced by using 0.5% or 1% GT or 0.5% CM to allow bracket bonding immediately after bleaching. Clinical significance: The use of antioxidants would allow clinicians to bleach teeth before orthodontic treatment without delaying bonding.

Effect of sodium ascorbate on the shear bond strength of orthodontic brackets to bleached enamel using universal dental adhesive

“…High concentration of hydrogen peroxide used in in-office bleaching can decrease the efficacy of sodium ascorbate in reversing the bond strength. [ 11 ] Studies that have reported the optimal efficacy of sodium ascorbate in increasing the bond strength after bleaching have used low-concentration carbamide peroxide as the bleaching agent. [ 3 11 24 27 28 29 30 ] Since hydrogen peroxide generates higher amounts of free radicals than carbamide peroxide, sodium ascorbate may be more effective in reversing the reduction in bond strength caused by carbamide peroxide rather than hydrogen peroxide.…”

“…[ 11 ] Studies that have reported the optimal efficacy of sodium ascorbate in increasing the bond strength after bleaching have used low-concentration carbamide peroxide as the bleaching agent. [ 3 11 24 27 28 29 30 ] Since hydrogen peroxide generates higher amounts of free radicals than carbamide peroxide, sodium ascorbate may be more effective in reversing the reduction in bond strength caused by carbamide peroxide rather than hydrogen peroxide. [ 11 31 32 ] In the present study, 40% hydrogen peroxide was used, which produces free radicals 10 times more than carbamide peroxide.…”

“…[ 4 7 ] The efficacy of sodium ascorbate in reversing the decreased bond strength to the bleached enamel has been previously documented; however, a few studies have reported its inefficacy in enhancing the bond strength. [ 11 12 ]…”

The effect of beer and milk tea on the shear bond strength of adhesive precoated brackets: An in vitro comparative study

“…Plants, tea and green tea contain natural polyphenols, which have several functions in the oral cavity, such as bacterial control and antioxidation, and have recently been employed as “processing cofactors” to improve the mechanical and functional properties of biomaterials [ 32 ]. Previous studies have used tea or green tea to reverse the SBS between adhesives and bleached enamel, with antioxidants being capable of neutralizing free radicals produced by bleaching treatment [ 33 , 34 ]. Epigallocatechin gallate is one of the most important polyphenols used in dental applications (EGCG).…”

Awareness of Therapeutic Benefits of Green Tea among Dental Fraternity

“…Most advanced studies evaluate the effects of different concentrations of sodium ascorbate (SA), green tea (GT), and chamomile (CM) on the shear bond strength (SBS) of metal orthodontic brackets bonded to teeth bleached with 40% hydrogen peroxide (HP). Results showed that bond strength can be enhanced by using 0.5% or 1% GT or 0.5% CM to allow bracket bonding immediately after bleaching [11] Recent studies have emphasized that in addition to the microbial activity, the host immuneinflammatory reactions destroy the oral tissues to a greater extent [12]. In such cases, green tea is considered to be a natural preventive and curative agent.…”