The effects of different whitening agents on the mineral change of tooth enamel and the evaluation of TOOTH color change after application

The aim of this in vitro study was to evaluate the mineral levels and color changes on enamel after the application of 5 different bleaching agents. 80 extracted, maxillary permanent central or lateral teeth were cut from the lower 2/3 of their roots. The samples were divided into 5 groups (n=12): (1) Opalescence Boost PF 40% (OPLB) (2) Opalescence Go 6% (OPLGO) (3) Opalescence PF 16% (OPL16) (4) Total Blanc Office H35 (TBL) (5) Cavex Bite&White 25% Office (CV). Calcium (Ca), Phosphorus (P), Potassium (K), Sodium (Na), Magnesium (Mg), Fluorine (F), Oxygen (O), Silicon (Si), Carbon (C), Nitrogen (N), Aluminum (Al), Tin (Sn), Strontium (Sr), Zinc (Zn) levels were measured using SEM-EDS device. SEM images were taken for each group. After color measurements using a spectrophotometer (VITA Easyshade V), bleaching applications were conducted according to manufacturers' instructions. Mineral content measurements were repeated after bleaching and 14 days after bleaching. Color measurements were repeated immediately after bleaching, 7 days after bleaching, and 14 days after bleaching. The samples were kept in artificial saliva at 37°C during the waiting periods. Statistical analysis for mineral values were carried out using ANOVA and Friedman tests. Color and ∆WID changes were analyzed using two-way mixed ANOVA (two-way (5x3) mixed ANOVA). There was a significant decrease in Ca percentages in TBL and CV groups and no significant differences were detected in the OPLB, OPLGO, and OPL16 groups after bleaching. There was no significant difference in P percentages in OPLB, OPLGO, OPL16, CV groups after bleaching, however a significant reduction was observed in the TBL group. Immediately after bleaching, OPLB, OPL16, and TBL groups exhibited higher ∆E00 values than the other groups. OPL16, TBL, CV groups preserved their color stability better over time after bleaching compared to other groups. OPLGO group showed lower WID change than the other groups after bleaching. TBL group, preserved its color stability better than other groups over time. After the bleaching applications using five bleaching agents, differences were observed between the average mass percentages of the elements in the enamel samples. Tested bleaching agents affected the mineral content of human enamel. Bleaching agents used in the study were differently effective on enamel color change. Keywords: Bleaching, Colour, Energy Dispersive X-ray Spectroscopy, Mineral Content, Spectrophotometer