Influence of simplified, higher-concentrated sodium ascorbate application protocols on bond strength of bleached enamel

Effect of Sodium Ascorbate, Grape Seed Extract, and Aloe Vera Application after In-Office Bleaching on the Bond Strength of Enamel: A 3-Year Evaluation

Introduction

Dental bleaching is the first choice to improve smile esthetics, but, in some cases, it needs to be associated with resin composite restoration to obtain a satisfactory result. Unfortunately, the bonding of resin-based materials can be impaired due to residual oxygen molecules, which can decrease the durability of the restoration.

Objectives

To evaluate the effect of the antioxidant application on the bond strength of bleached enamel after 24 hr and 3 years of water storage.

Methods

In total, 84 bovine teeth were used in this study. Of these, 77 were bleached with 35% hydrogen peroxide in a single session for three cycles of 15 min. Then, the specimens were divided into groups (n = 7 each): control (without bleaching), without antioxidant (WA) use; application of 10% sodium ascorbate (SA) gel, grape seed (GS) extract, and aloe vera (AV). The restorative procedure was performed immediately after bleaching, 7 and 14 days after bleaching. Specimens were sectioned and evaluated using microtensile bond strength (μTBS). Half of the resin-enamel sticks were tested after 24 hr, and the remaining half after 3 years of water storage. µTBS data were analyzed using a three-way analysis of variance, Tukey's test, and Dunnett's test.

Results

The lowest µTBS values were observed when the restoration was performed immediately after bleaching in the AV, GS, and WA groups when compared with the SA group (p < 0.005). However, no significant differences were observed among all groups after 3 years of water storage (p < 0.001).

Conclusions

SA at 10% was the most effective antioxidant agent for improving the immediate bond strength. However, independent of the antioxidant agent used, the bond strength values were maintained or recovered after 3 years of water storage. SA at 10% could be used to avoid delayed bonding procedures after in-office whitening without compromising bond strength over time. Clinical Significance. The use of antioxidants after dental bleaching can be effective in improving the bonding durability of the adhesive restorations.

Comparative Analysis of Shear Bond Strength of Composites to the Sodium Ascorbate Hydrogel-treated Bleached Enamel Surfaces: An In Vitro Analysis

Aim

To compare the shear bond strength of composites to the sodium ascorbate hydrogel-treated bleached enamel surfaces.

Materials and methods

Sixty-six extracted human maxillary first premolars were sectioned mesiodistally to obtain two nonocclusal surfaces (n = 132). The specimen in the experimental group (n = 80) were divided into four treatment groups depending upon bleaching protocols used: group I (10% FGM home bleach), group II (22% Pola Night home bleach), group III (37% light-activated in-office bleach Pola Office+), and group IV (35% Pola office in-office bleach without light activation). Specimens were subjected to the 1-minute application twice with sodium ascorbate hydrogel and were further divided into two subgroups “a” (acetone-based) and “b”(ethanol-based) depending upon the bonding agents used. The specimens of the control group (n = 52) were further divided into two treatment groups, that is, positive control and negative control. The specimens were tested using universal testing machine.

Results

The result of the present study revealed that the specimens bleached with 10% FGM home bleach showed the greatest shear bond strength and specimens bleached with 35% in-office bleach Pola Office showed the lowest shear bond strength.

Conclusion

A twice 1-minute application of sodium ascorbate hydrogel was effective to reverse the deleterious results of bleaching on enamel shear bond strength. Bonding agent containing acetone as a solvent (Prime and Bond NT) in this present study showed greater shear bond strength values than the bonding agent containing ethanol as a solvent (Adper Single Bond).

Statement of clinical relevance

The shear bond strength of composite restorative materials could be improved by applying sodium ascorbate gel to the bleached enamel surfaces.

How to cite this article

Pathak K, Kumar P, Choudhary A, et al. Comparative Analysis of Shear Bond Strength of Composites to the Sodium Ascorbate Hydrogel-treated Bleached Enamel Surfaces: An In vitro Analysis. Int J Clin Pediatr Dent 2021;14(6):741–747.

The Effect of Different Bleaching Protocols, Used with and without Sodium Ascorbate, on Bond Strength between Composite and Enamel

This in vitro study aims to evaluate whether a solution of 10% sodium ascorbate (SA) may exert a beneficial effect on the bonding of composite to enamel after using different bleaching agents and protocols. Microtensile bond strength (µTBS) was evaluated on 72 freshly extracted human central incisors, divided into eight experimental groups and one control group (total n = 9): Group 1 serves as control (nonbleached). Group 2 was bleached with 5% carbamide peroxide. Group 3 was bleached with 5% carbamide peroxide and then treated with 10% SA. Group 4 was bleached with 10% carbamide peroxide. Group 5 was bleached with 10% carbamide peroxide, then treated with 10% SA. Group 6 was bleached with 16% carbamide peroxide. Group 7 was bleached with 16% carbamide peroxide, then treated with 10% SA. Group 8 was bleached with 6% hydrogen peroxide. Group 9 was bleached with 6% hydrogen peroxide, then treated with 10% SA. All groups were restored immediately after the different treatments using a resin composite. The µTBS values were measured using a universal testing machine and statistical analysis was performed by means of normality and variance analyses, SIDAK test for univariate test and multiple comparisons, and Student test to compare µTBS values of each group with the control. The mean µTBS values in groups 2, 4, 6, 8 were significantly lower than controls. For groups 3, 5, 7, 9, subjected to antioxidant (10% SA) application, all µTBS values increased significantly. However, only for Groups 3 and 5 there was no significant difference with the control. Applying 10% SA for 10 min may improve the bond strength composite/bleached enamel just when whitening is performed with 5% and 10% carbamide peroxide.