In vitro bleaching effect of hydrogen peroxide with different time of exposition and concentration on shear bond strength of orthodontic brackets to human enamel: A meta-analysis of in vitro studies

Reduction of surface treatment time by combination of citric acid and ascorbic acid while restoring shear bond strength of metal brackets bonded to bleached enamel: a pilot study

BACKGROUND

To investigate the effect of a 50% ascorbic acid with 50% citric acid solution on the immediate shear bond strength (SBS) of metallic brackets after tooth bleaching. The enamel etching pattern and the required quantity of these combined acids as antioxidants following 35% hydrogen peroxide (HP) bleaching were also determined.

METHODS

The stability of the solution at room temperature was assessed at various time intervals. Fifty teeth were randomly divided into five groups: non-bleached (G1), bleached then acid etched (G2), bleached followed by a 10-minute treatment with 10% sodium ascorbate and acid etched (G3), 5-minute treatment with 50% ascorbic acid (G4), and 5-minute treatment with a combination of 50% ascorbic acid and 50% citric acid (G5). Groups G2, G3, G4 and G5 were bleached by 35% HP gel for a total of 32 min. Acid etching in groups G1, G2, and G3 was performed using 37% phosphoric acid (Ormco®, Orange, CA, USA) for 15 s. In all groups, metal brackets were immediately bonded using Transbond™ XT primer and Transbond™ PLUS adhesive, with light curing for 40 s. The SBS was tested with a universal testing machine, and statistical analysis was conducted using one-way ANOVA followed by Tukey's HSD test. The level of significance was set at p < 0.05 for all statistical tests.

RESULTS

Stability tests demonstrated that the combined acids remained effective for up to 21 days. Group G5 significantly increased the SBS of bleached teeth to the level of G1 (p < 0.05), while G3 did not achieve the same increase in SBS (p > 0.05). SEM analysis revealed enamel etching patterns similar to those of both control groups (G1 and G2). Kinetic studies at 6 min indicated that the antioxidation in G5 reacted 0.2 mmole lower than in G3 and G4.

CONCLUSION

5-minute application of the combined acids enhanced the SBS of bleached teeth comparable to unbleached teeth. The combined acids remain stable over two weeks, presenting a time-efficient, single-step solution for antioxidant application and enamel etching in orthodontic bracket bonding.

Bleaching effect on bonding performance of composite to enamel

This study aimed to assess the effects of dental bleaching on the immediate shear bond strength (SBS) of composite to enamel. Different bleaching methods and time intervals between bleaching and composite restoration were examined. A total of 45 enamel specimens were divided into three groups (n = 15) based on the applied bleaching protocol: in-office (A), at-home (B), and unbleached control (C). Groups A and B were then subdivided into three time intervals until bonding: 1, 3, and 7 days. The composite was bonded to enamel using self-etch adhesive technique and submitted to SBS testing. The enamel surface and adhesive interface were observed under scanning electron microscope (SEM). The highest average SBS was measured in the control (unbleached) group (31.1 ± 3.4). A significant difference in SBS was found between the control and in-office bleaching (p < .001), as well as between control and at-home bleaching (p = .034), while the difference between in-office and at-home bleaching methods was insignificant. In relation to the waiting period, a significant reduction in SBS (p < .001) was found 1 day post-bleaching. The weakest marginal sealing to enamel under SEM was observed also 1 day after bleaching. Both bleaching methods significantly reduced the SBS of composite to enamel, especially immediately after the bleaching procedure. Reduction in SBS is temporary and 3-day waiting period seems to be sufficient to reverse the adverse effects of bleaching. RESEARCH HIGHLIGHTS: SBS of composite to enamel is significantly reduced by bleaching procedures, especially immediately after bleaching. The reduction in SBS is temporary and reversible by delaying the restoration for a minimum of 3 days.

Most systematic reviews reporting adherence to AMSTAR 2 had critically low methodological quality: a cross-sectional meta-research study

OBJECTIVES

To analyze the methodological quality and characteristics of systematic reviews (SRs) that reported they were conducted in line with the AMSTAR 2 (A MeaSurement Tool to Assess Systematic Reviews).

STUDY DESIGN AND SETTING

This was a cross-sectional meta-research study. We searched MEDLINE and Embase. We included full reports of SRs reporting the study was conducted, prepared, or designed in line with the AMSTAR 2. Eligible SRs were those published from January 1, 2018, until May 3, 2022. We assessed the methodological quality of the included SRs using AMSTAR 2.

RESULTS

We included a total of 45 records. There were 43 SRs and 2 SR protocols. Among them, most were SRs of interventions that included primary studies on humans. More than half had a meta-analysis. According to our overall AMSTAR 2 assessments of included SRs, 35 SRs were of critically low confidence, 7 SRs were of low confidence, and one SR was of high confidence. There were no SRs of moderate confidence.

CONCLUSION

Even when authors indicate in their manuscripts that the SR was conducted/prepared/designed in line with the AMSTAR 2, it does not necessarily imply it is of high or even moderate confidence according to AMSTAR 2. A self-assessment with AMSTAR 2 could be required for submission and carefully checked by the editors/peer reviewers.

Effect of antioxidants after post-space irrigation on the adhesive interface of glass fiber post cementation

OBJECTIVE

This study evaluated the effects of antioxidants, 10% sodium ascorbate (SA) or 20% alpha-tocopherol (AT), after post-space irrigation with 2.5% sodium hypochlorite +17% EDTA (SH) or 1% peracetic acid (PA) on the adhesive interface after glass fiber post cementation.

MATERIALS AND METHODS

Sixty bovine roots were endodontically treated. After preparation, the post-space was irrigated with SH or PA followed or not by the use of antioxidants (SA or AT) (n = 10). Push-out bond strength test, failure mode, and dentin penetrability analysis using confocal laser microscope were performed in the cervical, middle, and apical thirds. Data from bond strength and dentinal penetrability were evaluated by one-way ANOVA and Tukey post hoc test (p < 0.05).

RESULTS

SH showed the lowest bond strength regardless of the third (p < 0.05). In apical third, mixed failure was the most incident in all groups. Only in the cervical third of the post-space, SH-AT provided the greatest tag extension of the cementation system into dentin (p < 0.05). However, in the middle and apical thirds, SH-AT, SH-SA, and PA-SA provided the largest tag extensions (p < 0.05), but similar to each other (p > 0.05).

CONCLUSIONS

The use of antioxidants only favored bond strength when SH was used and dentin penetrability of the adhesive and conventional resin cementation, regardless of the solution used to irrigate the post-space.

CLINICAL SIGNIFICANCE

The use of antioxidants (10% sodium ascorbate and 20% alpha-tocopherol) after post-space irrigation with sodium hypochlorite appears to increase the bond strength favoring the glass fiber post-cementation.

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.

The effect of ascorbic acid and cranberry on the bond strength, surface roughness, and surface hardness of bleached enamel with hydrogen peroxide and zinc phthalocyanine activated by photodynamic therapy

AIM

To evaluate the effect of different bleaching methods 40% (hydrogen peroxide) HP and Zinc Phthalocyanine (ZP) activated by photodynamic therapy (PDT) with the utilization of diverse procedures of reversal (10% ascorbic acid and 6% cranberry solution) on bond values, surface microhardness and surface roughness of bleached enamel surface.

MATERIAL AND METHODS

An aggregate of 60 extracted human mandibular molars was gathered and the buccal surface of each specimen was exposed to 2 mm of enamel surface for bleaching with chemical and photoactivated agents with the use of reversal solutions. Specimens were divided into six groups (n = 10) at random- Group 1: samples bleached with 40% HP with 10% ascorbic acid (reversal agent), group 2: ZP activated by PDT with 10% ascorbic acid (reversal agent), group 3: 40% HP with 6% cranberry solution as a reversal agent, group 4: ZP activated by PDT with 6% cranberry solution, group 5: 40% HP and group 6: ZP activated by PDT with no reversal agents. Resin cement restoration was performed via etch and rinse technique and SBS was estimated by using the universal testing machine, SMH by using Vickers hardness tester, and Ra by stylus profilometer. Statistical analysis was executed using the ANOVA test and the Tukey multiple tests (p<0.05).

RESULTS

Enamel surface bleached with 40% HP reversed with 10% ascorbic acid displayed the highest SBS while 40% HP with no reversal agent use showed the least SBS. For SMH, ZP activated by PDT when applied on the enamel surface and reversed with 10% ascorbic acid showed the highest SMH while when bleached with 40% HP and reversed with 6% cranberry solution showed the least SMH value. For Ra, Group 3: samples bleached with 40% HP with 6% cranberry solution as reversal agent showed the highest Ra value while bleaching of enamel surface with ZP activated by PDT with 6% cranberry displayed the least Ra value.

CONCLUSION

Bleached enamel surface with Zinc Phthalocyanine activated by PDT with the application of 10% ascorbic acid as reversal solution has demonstrated the highest SBS and SMH with acceptable surface roughness for bonding adhesive resin to the enamel surface.

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.

The Effect of Hydrogen Peroxide and Povidone-Iodine on the Shear Bond Strength of Orthodontic Brackets: An In Vitro Study

BACKGROUND: Chlorhexidine, which is the gold-standard antimicrobial mouthwash, cannot effectively decrease the count of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the causative agent for coronavirus disease-2019 (COVID-19). Since SARS-CoV-2 is susceptible to oxidation, mouthwashes containing oxidizing agents such as hydrogen peroxide (H2O2) or Povidone-iodine (PVP-I) are recommended to decrease the viral count. AIM: This study aimed to assess the effects of H2O2 and PVP-I mouthwashes on the shear bond strength (SBS) of metal orthodontic brackets to the enamel. MATERIALS AND METHODS: This in vitro experimental study evaluated 45 freshly extracted maxillary premolars. The teeth were cleaned and randomized into three groups (n = 15) for rinsing with distilled water (control group), 1% PVP-I (betadine), and 1.5% H2O2 for 60 s. All teeth were etched with 37% phosphoric acid gel, and metal orthodontic brackets were bonded to the teeth using the Transbond XT bonding system. The teeth were mounted in auto-polymerized acrylic resin and incubated in water at 37°C for 72 h. The teeth were then thermocycled for 48 h, and their SBS was measured in a universal testing machine. The adhesive remnant index (ARI) score was also calculated. The groups were compared by ANOVA and Chi-square Monte Carlo test. RESULTS: No significant difference was noted among the three groups in SBS (p = 0.938) or the ARI score (p = 0.780). CONCLUSION: Use of H2O2 and PVP-I mouthwashes has no adverse effect on SBS or mode of failure of metal orthodontic brackets bonded to enamel.

Mean Shearing Stroke Frequency of Orthodontic Brackets under Cycling Loading: An In Vitro Study

Based on the development of many adhesive systems and bonding techniques, bonding strength of orthodontic brackets has become even more important in modern clinical orthodontics. The aim of this study was to determine mean shearing stroke frequency of different orthodontic bracket types and bonding agents under cycling loading. Therefore, 10 different types of orthodontic bracket from 4 different brands were divided into 2 groups. Two different adhesives, namely Transbond™ XT etch-and-rinse for Group 1 and Transbond™ Plus self-etching-primer adhesive for Group 2 were considered. The brackets were tested under cycling loading force of 10-N and a crosshead speed of 300 mm/min and 40 cycle/min. The frequency of strokes that the brackets failed were determined and these data were analyzed by statistical analysis using an independent sample t-test and one-way analysis of variance (ANOVA). The level of significance was set at p < 0.05. Generally, differences between the frequency of shearing strokes of the bracket failures were found to be statistically significant depending on the type of adhesives and brackets (p < 0.05). The bonding technique for Group 1 was found to have a significantly higher shear bonding strength than Group 2. It is also seen that different types of bracket belonging to the same or different brands had different shear bonding strength. It may be concluded that: (i) all bracket types used in this study can be applied with both bonding techniques, (ii) in order to minimize the risk of hard tissue damage, ceramic brackets should be carefully bonded using the self-etching primary adhesive technique.

Effect of bleaching with carbamide peroxide on shear bond strength of orthodontic brackets: A meta-analysis of in vitro studies

INTRODUCTION

This study aimed to evaluate the effect of bleaching with carbamide peroxide (CP) according to different doses and intervals between bleaching and bonding on shear bond strength (SBS) of orthodontic brackets.

METHODS

Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, PubMed, and Scopus were searched for articles published up to June 2018. After removing the duplicates, two of the authors screened the titles and abstracts independently. Assessing the eligibility of the selected full texts was also conducted by two of the authors independently. Disagreements were resolved by discussion. Modified version of Cochrane's risk of bias tool was used to assess the quality of studies. Fifteen studies were selected.

RESULTS

Overall, bleaching with CP decreased the SBS by around 2MPa (P<0.0001). Using 10% CP decreased the SBS of the immediately bonded brackets by 5.13MPa (P<0.005). This value was 1.67MPa when the bonding procedure was postponed by one day (P<0.0001). Postponing the bonding procedure for longer periods did not cause a statistically significant change in SBS. Using 11-16% CP, the reduction in SBS of the immediately bonded brackets was 8.51MPa (P<0.01). The SBS decreased by 4.12MPa when the bonding procedure was postponed for 20days (P<0.05). According to one study, use of CP with>16% concentration seemed not to affect the SBS.

CONCLUSIONS

Bleaching with CP decreases the SBS, especially if the bracket bonding is performed shortly after bleaching. However, given the small number of articles interpretation should be made with caution.