In Vitro Effect Of Dental Adhesive Bonding Agent On Tooth Whitening Color Relapse

Background: Teeth bleaching lighten the shade of teeth and brighten the smile.Bleaching products contain peroxide that helps to remove deep intrinsic and surface extrinsic stains.These products use hydrogen peroxide in concentrations ranging from 25 percent to 40 percent.At-home and in-office are the two main teeth whitening methods.Both of the two bleaching methods are used to improve the teeth color whitening effect.Home bleaching method often takes up 4 weeks to complete.While in-office system takes up shorter time and with different light source to catalyze the bleaching agents,the duration treatment can be gradually reduced.The in-office systems use 35% hydrogen peroxide gels coupled with a high intensity light to whiten the teeth.The gums need to be protected with some systems,and then gels are placed on the teeth.A laser or plasma arc light source activates the peroxide to oxidize stains on the tooth surface.Once the tooth whitening procedures completed,the enamel surface become two to four shades lighter than before.Color relapse of tooth whitening resulting from dental bleaching is a phenomenon that occurs following bleaching procedures.When the tooth whitening treatment completed,color relapse usually occurs within the first 2 weeks and then whiteness of teeth will fade slightly slower and getting a stable surface color in 2 weeks to 6 month of time.The lasting effects of bleaching varied with each patient as it again depends on the inherent molecular structure of the enamel and also depends on the habits of the patient.It was thought that the initial whitening of the tooth color may be due to enamel dehydration.Objective: The purpose of this in vitro study is to evaluate the efficacy of Adper Single Bond 2 Adhesive resin on color relapse conditions after dental bleaching treatment.Adper Single Bond 2 Adhesive is the target resin with low-viscosity and high mobility characters,which enhanced the shear and wear resistance.Adper Single Bond 2 Adhesive has the property of reducing the surface adhesiveness of the stainable layer.The Adper Single Bond 2 Adhesive resin contains properties that resist micro-leakage and resin shrinking.The experiment evaluated the efficacy of the resin material to as it retards the initial color relapse phenomenon on teeth after whitening procedures.The study is to conduct measurements through colorimeter on enamel surface color changes and observation on microstructures with scanning electron microscopy.Material and Method: Collect tooth samples with soft tissues removed and etching process for 15 seconds.The collected test samples need to meet the requirement of no decay,no prosthetic restoratives,no filling materials,no cracks and no obvious defects.48 samples were divided into laser bleaching group(L)and plasma bleaching group(P).Spectra-colorimeter(SCM-104)was performed to detect and record the color variations CIE(L*,a*,b*)for the surface treated laser and plasma whitened groups.The measurements were conducted before and after the bleaching procedures.Aging test was conducted in tea distilled water solution after Adper Single Bond 2 Adhesive applied on bleached teeth surface.The colorimeter measures the color differences(ΔE)which provided comparative values for statistical analysis.The measurements were conducted during the 1、 3、 5、 7、 14、 21、 28、35 and 42 days after the bleaching and surface resin applied.Result: It concluded that the Adper Single Bond 2 Adhesive,a light-activated resin composite surface protector was a good surface protection material against color relapse of the teeth.Based on the results,it demonstrated that one layered Adper Single Bond 2 Adhesive presented with less color changes on the enamel surface,and created a smooth surface,when applied on the whitening teeth.The results supports that application of Adper Single Bond 2 Adhesive for surface treatment of post laser and plasma ray whitened teeth enabled the teeth color measurements to maintain with in a stable range.The result from scanning electron microscope observation also show the resin created a smooth surface after whitening,thereby offering a condition for isolating pigments re-stain.Conclusion: Together with the results on enamel surface color changes,statistics analysis and SEM(Scanning Electron Microscope)imagery,the study provided positive support on efficacy of Adper Single Bond 2 Adhesive resin in slowing initial dental bleach color relapse and re-stain conditions.In this study the result supports the Adper Single Bond 2 Adhesive to be an appropriate surface-treatment material which achieves a relatively smooth and even surface that reduces the possibility of color staining on enamel and provide a good basic foundation on color relapse resistance mechanism.Furthermore study is required to understand the full mechanism of the color relapse phenomenon and the role of surface protective resin in these processes.