Natural antioxidants to restore immediate bond strength to bleached enamel: Systematic review and meta-analysis of in vitro studies

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.

Antioxidant effect on shear bond strength of orthodontic brackets after tooth bleaching: A scoping review of in vitro studies

INTRODUCTION

Tooth bleaching was reported to decrease bond strength of orthodontic brackets. The antioxidant application was investigated to reverse the bleaching effect for immediate bracket bonding. This scoping review of in vitro studies is to assess systematically the effect of antioxidant application on shear bond strength (SBS) before orthodontic bracket bonding after tooth bleaching.

MATERIALS AND METHODS

This review was provided according to the Preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews (PRISMA-ScR) guidelines. An electronic literature search was performed for full-text articles in English via Scopus, Web of Science, MEDLINE/PubMed, and Google Scholar databases from 2012 to May 9, 2023.

RESULTS

A total of 549 records were retrieved from the electronic search, and 361 after discarding duplicates. According to eligibility criteria, 23 records were included in this study.

CONCLUSION

Included studies revealed that antioxidants could increase the SBS of brackets after bleaching. However, there was controversiality whether SBS was just improved or restored to the unbleached level according to various factors, including the antioxidant type, concentration, application time, and form. Most studies reported that 10% sodium ascorbate (SA), ascorbic acid, green tea (GT), and tocopherol solutions restored SBS of metal brackets but not ceramic brackets. The result of 10% SA and GT gel was controversial. Lower concentrations than 10% was effective with pink bark, grape seed, quercetin flavonoid, and chamomile to restore SBS. The included studies revealed that retinol acetate, gooseberry, and dimethyl sulfoxide did not restore SBS.

Fracture resistance and bonding performance after antioxidants pre-treatment in non-vital and bleached teeth

This study aimed to evaluate the effect of antioxidant solutions on fracture strength and bonding performance in non-vital and bleached (38% hydrogen peroxide) teeth. One hundred and eighty dentin specimens were obtained, 60 for each test: fracture strength, hybrid layer thickness, and bond strength. The groups (n=10) were randomly composed according to post-bleaching protocol: REST - restoration, without bleaching; BL - bleaching + restoration; SA - bleaching, 10% sodium ascorbate solution, and restoration; AT - bleaching, 10% α-tocopherol solution, and restoration; CRAN - bleaching, 5% cranberry solution, and restoration; CAP - bleaching, 0.0025% capsaicin solution, and restoration. Data were analyzed with ANOVA, Kruskal-Wallis, Dunn, and Qui-Square tests (α=0.05). The highest fracture strength values were observed in REST (1508.96 ±148.15 N), without significant difference for the bleached groups (p>0.05), regardless of the antioxidant use. The hybrid layer thickness in the group that was not subjected to bleaching (REST) was significantly higher than in any other group. The bond strength in the bleached and antioxidants-treated groups (SA, AT, CRAN, CAP) has no differences with the bleached group without antioxidants (BL). Adhesive failures were predominant in the groups that did not receive the antioxidant application. In conclusion, the evaluated antioxidants did not show an effect on the fracture strength, hybrid layer thickness, or bond strength of dentin bleached after endodontic treatment. The application of 10% sodium ascorbate, 10% alpha-tocopherol, 5% cranberry, or 0.0025% capsaicin solutions is not an effective step and should not be considered for the restorative protocols after non-vital bleaching.

Fracture strength and bonding interface morphology of CAD/CAM-fabricated ceramic laminate veneers on bleached enamel treated with two different antioxidants

This study aimed to investigate the effects of two antioxidants and their application time on the fracture strength of computer-aided design and computer-aided manufacturing (CAD/CAM)-fabricated ceramic laminate veneers to bleached enamel, as well as their effects on the bonding interface micromorphology. Eight groups were set: Group NC (without bleaching and antioxidant treatment); Group NA (bleaching without antioxidant treatment); Group SA30, SA60, SA120 and Group PAC30, PAC60, PAC120 (bleaching and treating with sodium ascorbate or proanthocyanidins for 30, 60, and 120 min, respectively). After cementation of veneers, fracture strength values and failure modes were analyzed. The bonding interface morphology was observed by confocal laser scanning microscopy. The fracture strength was impaired when cementation procedure was performed immediately after bleaching. This reduction in fracture strength was reestablished with antioxidant treatment, and an extended treatment time contributed to better improvement. The resin tags at the bonding interfaces of the bleached enamel were impaired. Antioxidant treatments were able to reverse this unfavorable trend.

One-Step Surface-Treatment Reagent (35% 3-O-Ethyl-l-ascorbic Acid Plus 50% Citric Acid Solution) Restores the Shear Bond Strength of Metal Brackets Bonded to Bleached Human Enamel: An In Vitro Study

This study investigates how a new substance, composed of ethyl ascorbic acid and citric acid, affects the shear bond strength (SBS) of metal brackets when bonded to bleached teeth. Forty maxillary premolar teeth were used and randomly placed into four groups (n = 10): the control group did not undergo bleaching; the remaining groups underwent bleached using 35% hydrogen peroxide. In group A, 37% phosphoric acid was applied after bleaching. In group B, 10% sodium ascorbate was used for ten minutes before 37% phosphoric acid. In group C, 35%3-O-ethyl-l-ascorbic acid plus 50% citric acid solution (35EA/50CA) was applied for 5 min. The subgroups were bonded immediately after bleaching. The SBS was determined with a universal testing machine and analyzed using one-way ANOVA and then Tukey's HSD tests. Adhesive remnant index (ARI) scores were determined with a stereomicroscope and analyzed with a chi-squared test. The significance level was 0.05. Group C demonstrated significantly higher SBS values than group A (p < 0.001), but was not significantly different than the control group or group C (p > 0.05). The ARI scores were significantly different among the groups (p < 0.001). In conclusion, enamel surface treatment using 35EA/50CA improved the reduced SBS to an acceptable clinical level and reduced the clinical chair time.

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

BACKGROUND

Deterioration in shear bond strength has been reported after immediate bracket bonding following hydrogen peroxide bleaching. This study compared the effectiveness of three antioxidant agents, namely, alpha-tocopherol, green tea extract, and sodium ascorbate, in reversing the bleaching effect and as possible alternatives to delayed bonding.

METHODS

A total of 105 extracted human premolars were arbitrarily assigned to 7 groups (n = 15 each), including group 1 as the unbleached control group and six experimental groups, which were bleached with 40% hydrogen peroxide in three sessions of 15 min each. In experimental group 2, bonding was performed immediately after bleaching, whereas in groups 3 and 4, bonding was delayed for 1 and 2 weeks, respectively; meanwhile, the specimens were immersed in artificial saliva at 37 °C. Groups 5, 6, and 7 were treated immediately after bleaching with 10% of alpha-tocopherol, green tea extract, and sodium ascorbate solutions, respectively, for 15 min. Specimens were processed using 500 thermal cycles between 5 and 55 °C, with a dwell time of 30 s after 24 h of bracket bonding, and then tested for shear bond strength. The adhesive remnant index was examined to evaluate fracture mode. One-way analysis of variance, Kruskal-Wallis H, and post hoc Tukey's honestly significant difference tests were used to compare the data. Significant results were subjected to pairwise comparisons with Bonferroni's correction-adjusted of p values ≤ 0.050.

RESULTS

Shear bond strength was significantly lower (p < 0.001) in the immediate bonding and 1-week delay groups than in the control group. However, no significant difference was detected among the 2-week delay, antioxidant-treated, and control groups (p > 0.05).

CONCLUSIONS

Application of 10% alpha-tocopherol, green tea extract, or sodium ascorbate for 15 min could restore shear bond strength after 40% hydrogen peroxide bleaching as an alternative to delay in bracket bonding.

In-vitro evaluation of the effectiveness of polyphenols based strawberry extracts for dental bleaching

To formulate a dental bleaching agent with strawberry extract that has potent bleaching properties and antimicrobial efficacy. Enamel specimens (3 × 3 × 2 mm³) were prepared. Quaternary Ammonium Silane (CaC2 enriched) was homogenized with fresh strawberries: Group 1: supernatant strawberry (10 g) extract < Group 2: supernatant strawberry (10 g) extract + 15%HA (Hydroxyapatite) < Group 3: supernatant strawberry (10 g) extract + 15% (HA-2%k21) < Group 4: supernatant strawberry (20 g) extract only (20 g strawberries) < Group 5: supernatant strawberry (20 g) extract + 15% HA < Group 6: supernatant strawberry (20 g) extract + 15% (HA-2%K21) < Group 7: In-office Opalescence Boost 35%. Single-colony lactobacillus was examined using confocal microscopy identifying bacterial growth and inhibition in presence of bleaching agents using 300 µL aliquot of each bacterial culture. Images were analysed by illuminating with a 488 nm argon/helium laser beam. Colour difference (∆E00) was calculated using an Excel spreadsheet implementation of the CIEDE2000 colour difference formula and colour change measured between after staining and after bleaching. Scanning electron microscope was used to image specimens. Raman spectra were collected, and enamel slices were used for STEM/TEM analysis. HPLC was used for strawberry extract analysis. Nano-indentation was performed and X-ray photoelectron spectroscopy. Antioxidant activity was determined along with molecular simulation. hDPSCs were expanded for Alamar Blue Analysis and SEM. Mean colour change was significantly reduced in group 1 compared to other groups (p < 0.05). CLSM showed detrimental effects of different strawberry extracts on bioflms, especially with antimicrobial (p < 0.05). Groups 1, 2 and 3 showed flatter/irregular surfaces with condensation of anti-microbial in group 3. In strawberry specimens, bands predominate at 960 cm^-1. HPLC determined the strawberry extracts content. Molecular simulation verified interaction between calcium and polyphenol components. XPS peak-fitted high-resolution corresponding results of Ca2p_3/2 and Ca2p_1/2 for all k21 groups. Combination of 10 g strawberry extract supernatant and 15% (hydroxyapatite 2%k21) improved the whiteness and provided additional antimicrobial potential. The novel strawberry extract and antimicrobial based dental formulation had immediate bleaching effect without promoting significant changes in enamel morphology.

The Effect of Antioxidants on Dentin Bond Strength after Application of Common Endodontic Irrigants: A Systematic Review

The purpose of this systematic review was to evaluate how an antioxidant treatment would influence the immediate bond strength of dental adhesives to endodontically treated dentine. Scientific evidence was researched in five databases using selected descriptors. Two independent reviewers conducted the investigation and assessed the data and methodological quality of the studies. Inclusion and exclusion criteria were specified for article selection; only studies in English and published between 2001 and 2022 were evaluated. A total of 18 studies were selected and analysed. According to most studies, the irrigation procedure and substrate preparation in endodontic therapy may affect the immediate bond strength. Antioxidants can improve bond strength and adhesion following the use of the most frequently used irrigants in root canal treatments. Therefore, antioxidant treatment can be considered a proper technique to enhance the bond strength of endodontically treated teeth.

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

AIM

This study aimed to evaluate the effect of using whitening dentifrices during at-home bleaching on the shear bond strength (SBS) of resin composite to dentin, and investigate whether the increased polymerization time would improve SBS.

METHODS

Ninety-six bovine incisors were divided into 4 groups of 24, according to the whitening treatment applied as follows: group 1, at-home bleaching + brushing with a regular dentifrice; group 2, at-home bleaching + brushing with a whitening dentifrice containing ozone; group 3, at-home bleaching + brushing with a commercial whitening dentifrice; and group 4 (control), no whitening/brushing treatment. Each group was divided into two subgroups (n = 12) to assess the effect of curing time (20 versus 80 s) on SBS. A self-etch adhesive was bonded to dentin, and after 2-day water storage, SBS was determined.

RESULTS

SBS was significantly affected by the whitening treatment (P = 0.03), but increasing the curing time had no significant effect on SBS (P = 0.137). Bond strength in group 1 was comparable to the control group (P > 0.05). The specimens in group 3 displayed significantly lower SBS than either group 4 or group 1 (P > 0.05). No significant difference was observed between the SBS of group 2 compared to any other group (P > 0.05). There was no significant association between the treatment group and failure type (P > 0.05).

CONCLUSION

The bonding interface was not negatively influenced by the at-home bleaching procedure. However, using a commercial whitening dentifrice during at-home bleaching produced a significant detrimental effect on SBS. Extending the curing time would have no beneficial effect on adhesion to a whitened dental substrate.

Shiri MH, Sohrabniya F. Comparative evaluation of the postbleaching application of sodium ascorbate, alpha-tocopherol, and quercetin on shear bond strength of composite resin to enamel

OBJECTIVE

This study aimed to evaluate and compare the impacts of the postbleaching application of sodium ascorbate, alpha-tocopherol, and quercetin on the shear bond strength (SBS) of composite resin.

MATERIAL AND METHODS

60 extracted intact maxillary first premolars were collected and were randomly divided into five experimental groups as follows (n=12): Group A (negative control): no bleaching, Group B (positive control): bleaching with 40% hydrogen peroxide (HP), Group C: HP±10% sodium ascorbate for 10min, Group D: HP±10% alpha-tocopherol for 10min, and Group E: HP±1% quercetin for 10min. Composite bonding was done immediately after bleaching for Groups B-E and without any treatment for Group A. After being stored in distilled water at room temperature for 24h, all specimens were tested for SBS in the universal testing machine. One-way analysis of variance and Tukey's post-hoc test were used to analyze the SBS values of all groups.

RESULTS

The results showed that the bonding of composite to the unbleached group exhibited the highest mean value of SBS (22.68±2.91MPa). Among the antioxidant-treated groups, the highest SBS value was detected in quercetin-treated specimens (15.45±1.58MPa), which was significantly different from the positive control group (p<.05).

CONCLUSION

It could be concluded that 10% quercetin applied for 10min increased the bond strength to bleached enamel, but it was not able to reverse it completely.