ABSTRACT
Introduction:
The application of the antioxidants after the teeth are bleached has been advocated to fasten the restorative process post-bleaching. The motive of this study was to examine and assess the micro-tensile binding strength of bleached enamel to the resin using a variety of antioxidant solutions. Finding the reason for the tooth fracture was the secondary outcome measured.
Materials and Methods:
An in vitro study was planned with 100 human extracted teeth, with 20 in each group with one as controls and 4 others tested for the antioxidants sodium ascorbate, epigallocatechin gallate, chitosan, and proanthocyanidin application. The bond strength of bleached enamel to the resin was well as the failure type was assessed after the values were noted and compared using the ANOVA and Tukey’s methods keeping P < 0.05 as significant.
Results:
Epigallocatechin gallate specimens displayed the maximum micro-tensile bond strength under the investigational circumstances, whereas controls displayed the lowest micro-tensile bond strength. There was statistical alteration in micro-tensile bond strengths between all the groups except between epigallocatechin gallate vs chitosan and sodium ascorbate vs proanthocyanidin. High statistical significance was seen between the control and the antioxidant groups as well as between sodium ascorbate and epigallocatechin gallate and chitosan.
Conclusion:
The antioxidant chemicals significantly augmented the bond strength of bleached enamel to the resin that had been bleached. Also, when compared to the other experimental groups, epigallocatechin gallate and chitosan treatment displayed the greatest mean bond strength values.
KEYWORDS: Antioxidants, bleaching, epigallocatechin gallate, in vitro, micro-tensile strength
INTRODUCTION
When a tooth is unsightly or discolored, patients are understandably concerned since it can greatly influence their dental health, which in turn can have a negative impact on their overall well-being. Even though there are intrinsic and extrinsic causes of tooth discoloration, it can be treated with porcelain whitening, porcelain veneers, crowns, and enamel micro-abrasion.[1,2,3] The oxidizing chemical hydrogen peroxide (HP), which diffuses into the tooth and then splits to produce free radicals, targets the organic pigmented molecules contained within the tooth tissue. The chromophore molecules will consequently shrink, losing color, and packing density. Also, due to the shift in the absorption spectrum, the tooth will eventually require bleaching.[2,3,4,5] The layers of dentine and enamel are hypothesized to be permeable to HP, which might then enter the pupal cavity. The oxygen left over from the bleaching agent inhibits the resin from polymerizing after it has been exposed to the pulp. Thus, a waiting time of 7-21 days is suggested to prevent the resin from being negatively impacted by antioxidants. Yet, due to the patients’ immediate cosmetic requirements, it is important to consider alternative methods to repair the diminished binding strength of enamel after bleaching. Many studies have found no discernible alteration between applying an antioxidant surface treatment immediately following the bleaching technique and postponing restorative bonding for at least two weeks. To shorten the time between bleaching and the restorative procedure, the use of antioxidant compounds has been recommended. Antioxidants can be used to remove reactive oxygen from the tooth substrate in order to accomplish this.[6,7]
MATERIALS AND METHODS
We gathered, cleaned, and stored in saline one hundred extracted human permanent incisor teeth. None of the incisors had any fractures, cracks, or cavities. After that, the teeth underwent a prophylaxis and were cleaned for an entire day with thymol at a 0.9% concentration. The teeth were sliced, detaching the crowns from the roots, under irrigation. The labial surfaces of the crowns were parallel to the horizontal plane and were enclosed in self-curing acrylic resin. For the purpose of creating flat enamel surfaces, 1.5 mm of enamel was left uncut. A large amount of water jet was used to make the preparations. All of the teeth specimens created utilizing the aforementioned technique were divided into five groups: control (n = 20), sodium ascorbate (n = 20), epigallocatechin gallate (n = 20), chitosan (n = 20), and proanthocyanidin (PA) (n = 20).
RESULTS
To test the composite’s capacity to adhere to bleached enamel, proanthocyanidin, sodium ascorbate, chitosan, and epigallocatechin gallate were used as antioxidants. Epigallocatechin gallate specimens showed the highest micro-tensile bond strength, whereas controls showed the lowest (8.21 Mpa). The average bond strengths for sodium ascorbate, proanthocyanidin, chitosan, and epigallocatechin gallate under micro-tensile tension are 12.23 MPa, 14.69 MPa, 13.84 MPa, and 11.25 MPa, respectively. A substantial statistical difference (P0.001) was observed between the groups [Table 1]. There was statistical variance in micro-tensile bond strengths between all the groups except between epigallocatechin gallate vs chitosan and sodium ascorbate vs proanthocyanidin. High statistical significance was seen between the control and the antioxidant groups as well as between sodium ascorbate and epigallocatechin gallate, chitosan [Table 2].
Table 1.
Evaluation of the bond strength of the antioxidants (Mpa)
| Group | n | Mean | SD | Minimum | Maximum | P |
|---|---|---|---|---|---|---|
| Control | 20 | 8.21 | 4.01 | 9.32 | 12.31 | <0.001 |
| Sodium Ascorbate | 20 | 12.23 | 2.36 | 11.26 | 15.23 | |
| Epigallocatechin gallate | 20 | 14.69 | 4.36 | 13.21 | 19.21 | |
| Chitosan | 20 | 13.84 | 5.01 | 11.23 | 19.24 | |
| Proanthocyanidin | 20 | 11.25 | 6.12 | 10.00 | 16.01 |
Table 2.
Intergroup comparison of the micro-tensile bond strength
| Group | Control | Sodium Ascorbate | Epigallocatechin gallate | Chitosan | Proanthocyanidin (PA) application |
|---|---|---|---|---|---|
| Control | <0.001 | <0.001 | <0.001 | <0.001 | |
| Sodium Ascorbate | <0.001 | <0.001 | <0.001 | 0.062 | |
| Epigallocatechin gallate | <0.001 | <0.001 | 0.214 | 0.001 | |
| Chitosan | <0.001 | <0.001 | 0.214 | 0.031 | |
| Proanthocyanidin | <0.001 | 0.062 | 0.001 | 0.031 |
DISCUSSION
Whitening the teeth that show when you smile is something that can be done in a variety of settings, including professionally and at home. When carried out in a therapeutic environment, a wide range of applications are utilized, each of which contains HP as an essential component. Bleaching can result in a number of unpleasant side effects, the most common of which is post-operative sensitivity, which accounts for 62.2% of all problems.[8] Regardless of the methodology that was utilized, clinical tests revealed that the incidence of sensitivity ranged anywhere from 18% to 78%.[4,9,10] Bleaching also has the unfortunate side effect of lowering the strength of the binding between composite resin and enamel. The binding strength of a composite restoration is dramatically diminished as soon as the bleaching process has been completed. Bleaching was demonstrated to be able to increase the solubility of cements such as glass-ionomer and other cements. When applied directly on bleached enamel, the bonding strength between the resin and the tooth was lowered by 40–55%.[2,3,4,5] The oxidative action of HP is the cause of reduced interface bond strength more often than any other factor. Several different approaches have been taken to fix the problematic resin adhesion. Delaying the restoration procedure by a couple of days will give the remaining oxygen time to degrade, which is a course of action that is usually proposed.[11] Several writers recommend waiting twenty-four hours before attempting any restoration therapies on enamel after bleaching it with 10% carbamide peroxide.[12] A waiting period of one week was recommended by a few of the authors.[13] According to the findings of a number of papers, the time frame of twenty-four hours is insufficient, and it takes at least one to three weeks to completely restore the binding strength to enamel when larger concentrations are involved.[6,7,11] This study had only a few restrictions on its scope. Due to the in vitro nature of the research, it was possible that the findings would be different if the same antioxidants were employed in a clinical setting. Hydrogen peroxide was the only bleach that was employed in this investigation; however, there are various different bleaches that are commonly used and can be found in homes and offices. This is the second limitation of the study.
CONCLUSION
The findings of this study allow for the conclusion that the use of antioxidant chemicals considerably improved the binding strength of composite to enamel that had been bleached. However, these findings are limited by the scope of the study. In addition to this, when compared to the other experimental groups, the epigallocatechin gallate and chitosan treatment demonstrated the highest mean bond strength values. When compared to the group that served as the control, the binding strength achieved with epigallocatechin gallate and chitosan was much higher. In terms of failure mode, the group that applied epigallocatechin gallate and chitosan displayed a more desirable type of failure than the other groups.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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