This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract The aim of this study was to evaluate the effect of bleaching and thermocycling on microshear bond strength of bonded resin composites to enamel. Each essential group was randomly subdivided to two subgroups:
Click here to view Mean shear bond strength of the control group Group IIA no antioxidant used, immediate bonding had least shear bond strength value Discussion Tooth discoloration has always been a factor of utmost concern as more emphasis is being placed on esthetics.
With the growing awareness of esthetic options, there is a great demand for various modalities in treating discolored teeth. Tooth bleaching has been an option since late s.
Carbamide peroxide, a biological oxidant, is still the most commonly used bleaching agent which releases free radicals in the form of nascent oxygen and hydroxyl or perhydroxyl ions, when applied to the dental structure.
Free radical is any molecule that has one unpaired electron, providing its high reactivity that actualizes the bleaching process by oxidizing the macromolecules of stains quickly and breaks them into linear fragments, consequently diffusing across dental hard tissues.
Since these oxygen products will persist until removed by pulpal microcirculation, clinicians must allow some time to elapse between the bleaching procedure and restorative treatment to achieve desirable bond strength.
Nevertheless, there appears to be no consensus regarding the necessary waiting period, though studies suggest that elimination of residual peroxide degradation product is time dependant. After 2 weeks storage period, the peroxide ions decompose and the substituted hydroxyl radicals re-enter the apatite lattice, resulting in the elimination of the structural changes caused by incorporation of the peroxide ions.
It is a potent antioxidant capable of quenching reactive free radicals in biological systems. Proanthocyanidins are a group of polyphenolic bioflavonoids found in high concentrations in natural sources such as grape seed extract, pine bark extract, cranberries, lemon tree bark, and hazelnut tree leaves.
In vitro studies have confirmed that OPCs are 50 times more effective than vitamin E and 20 times more powerful than vitamin C. Lycopene exerts potent anti-inflammatory effects through its action as an antioxidant and free radical scavenger.
Due to its potent antioxidant potential, lycopene obtained from tomato extract was taken up for the study. Therefore, the present study was designed to evaluate the neutralizing effects of various antioxidants on the shear bond strength of composite resins to bleached enamel.
The shear, rather than tensile mode of testing, was selected for this study, as it would more accurately reflect the type of forces generated on veneer restorations in the tooth. Bond strength was the lowest for group II bleached and not treated with antioxidants: This reduced bond strength could be attributed to the residual oxygen free radicals on the enamel surface.
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In group IIB delayed, no antioxidant: This could be attributed to the partial loss of oxygen diffusion layer at the tooth and composite interface. Group III sodium ascorbate showed the highest bond strength among the antioxidant treated groups; both when bonding was performed immediately These results concur with those of Turkun et al.
The results of this study are in accordance with previous investigations done by Lai et al. Although the surface treatment with group IV proanthocyanidin showed increased bond strength Molecular weight of the materials also seems to have played a role. Hydrogen peroxide, being a low-molecular-weight substance, permeates into the dental hard tissues and breaks down into free radicals,  so surface treatment done with any antioxidant to remove these free radicals should have low molecular weight for efficient scavenging action.
Tannins have a molecular weight of and are highly hydroxylated structures that can form insoluble complexes with proteins and carbohydrates. Probably, this may be the reason for better bond strength with sodium ascorbate compared to proanthocyanidin.
Although the molecular weight of lycopene On the other hand, proanthocyanidin has the specificity for hydroxyl free radicals and it possesses multiple donor sites, which enables it to trap superoxide radicals.
Lycopene, a carotenoid compound, is most likely involved in the scavenging of two reactive oxygen species, namely, singlet oxygen and peroxide radicals. Further, they are effective deactivators of electronically excited sensitizer molecules which are involved in the generation of radicals and singlet oxygen.
Singlet oxygen quenching by carotenoid occurs via physical quenching i.Pessarello et al. – Bond strength of dentin submitted to bleaching and restored with different materials The specimens were embedded into self-cured acrylic resin (JET Clássico, São Paulo, SP, Brazil), with the aid of PVC rings ( cm of inner diameter.
Effect of 10% sodium ascorbate on the shear bond strength of composite resin to bleached bovine enamel J Oral Rehabil ; , 7 Attin T, Vollmer D, Wiegand A, Attin R, Betke H. Subsurface microhardness of enamel and dentin after different external bleaching procedures Am J .
This study evaluated the microshear bond strength of composte resin to teeth bleached with commercial whitening strips and compared with those bleached with home bleaching gel.
In conclusion, dental bleaching did not affect resin-enamel bond strength, regardless of the waiting time to place the restoration after bleaching.
This study investigated the influence of the waiting time for placing resin composite (RC) restorations after dental bleaching on the shear bond strength (SBS) to enamel. Objectives The aim of this study was to evaluate the effects of time elapsed since bleaching and different bleaching regimens on the microtensile bond strength of resin composite to enamel.
Effect of different antioxidants on reversing compromised resin bond strength after enamel bleaching: An in vitro study Hulas Gogia, Sonali Taneja, Mohit Kumar, Sonal Soi I.T.S Centre for Dental Studies and Research, Ghaziabad, Uttar Pradesh, India.