21 Bleaching effect of gels with different thickeners and mineral supplementation

Purpose The aim of the study was to evaluate the bleaching effect of gels with calcium (Ca) and phosphorus (P) mineral supplementation, in amounts corresponding to the saturation concentration (SC) and the solubility limit (SL), containing different thickening agents. Methods Bleaching gels containing 35% hydrogen peroxide (PH) were manipulated and the thickeners were used: carbopol 980 (CB); aerosil 200 (SP); poloxamer 407 (PX); guar gum (GG) and hydroxyethylcellulose (HEC). The pH was adjusted to 7. The SC of the Ca and P salts, in the composition of the bleaching gel with the different thickeners and the SL of the Ca and P salts were determined. A total of 360 circular specimens obtained from bovine incisor teeth were prepared. The baseline color reading was performed with a colorimetric spectrophotometer. The specimens were divided into 5 experimental groups according to the type of thickener. Each group was divided into three subgroups (n=20), according to mineral supplementation (0 - no supplementation; SC - addition of Ca and P according to the SC calculated for that thickener; SL - addition of the maximum amount of Ca and P according to SL). In addition, three control groups (n=20) were prepared, namely: NC (negative control – ultra pure water); PC (positive control – 35% pH without the addition of any mineral); CPC (commercial positive control - commercial Whiteness HP gel). In the respective specimens, 0.50g of the different bleaching gels was applied for 45minutes. All specimens were then immersed in artificial saliva for 7 days and the final color evaluated. Results Data from the experimental groups were statistically analyzed with 2-way ANOVA (thickener type x mineral supplementation) and Tukey test. Comparison with control groups was performed using Dunnett's test ( = 5%). ANOVA showed significant differences for the two factors (p<0.05). The results were: type of thickener (p=0.0001): SP - 5.40(2.92)a, GG - 3.13(1.83)a, PX - 3.18(2.57)ab, HEC - 3.82(2.05)bc, CB - 4.79(3.26)c. mineral supplementation (p=0.2853): 0 - 4.37(2.60)a, SC - 4.04(3.07)a, SL - 3.79(2.42)a. The results of Dunnett's test showed that there were no significant differences between PC and CPC and the experimental gels. All groups showed significant differences in relation to NC. Conclusion It can be concluded that mineral supplementation and the use of different types of thickeners did not affect the whitening effect.