THE EFFECT OF BLEACHING AGENTS ON THE HUMAN ENAMEL
MOHAMED ATIF SAID AHMED*, MOHAMED El-SHENAWY**, REFAAT EID***
Department of Anatomy*, Faculty of Medicine, Zagazig University, Department of endo**, Faculty of Dentistry, Tanta University, EM unit***, Faculty of Sciences, Zagazig University, Egypt. King Khaled University, Abha, KSA
The use of a variety of bleaching techniques has attracted much interest from the profession, as they are relatively non-invasive and simple to carry out. Bleaching has become a popular and conservative alternative for patients seeking improved esthetics in a relatively short period of time and at low cost. One effective tooth bleaching agent is the hydrogen peroxide, usually used with high concentrations.The goal of the present laboratory study was to analyze the effect of two bleaching agents (Hydrogen peroxide 30% and Opalescence Extra Boost 38%) on the enamel of extracted human teeth.MATERIALS AND METHODS: Thirty two extracted permanent, decay-free, human molar teeth were used. One half of each tooth was used for control and the remaining half was bleached. Hydrogen peroxide 30% and Opalescence Extra Boost 38% were applied on, for 4 hours per day, the treatment was repeated daily for 14 days. The morphology of the enamel surfaces were then analyzed using scanning electron microscopy. The bleached parts were compared with non-bleached parts for hardness, tensile strength and for calcium, and phosphorus concentration. RESULTS: High concentration of bleaching agents used in this study had a tendency to promote an increase in density of pits, areas of mild erosion and morphological alterations in the most superficial enamel crystallites. Surface microhardness decrease by 11.4%, 6.7% in 30% hydrogen peroxide and Opalescence Extra Boost 38% respectively. Specimens submitted to bleaching treatment showed a significant reduction of surface microhardness. Tensile strength of enamel was reduced by 14.3 %, 8.9 % in bleaching by hydrogen peroxide 30% and Opalesence Extra Boost 38% respectively. Mean tensile strength of all bleached groups were significantly lower than those of non-bleached groups. The amount of calcium loss was 1.96 µg/mm2 and 1.42 µg/mm2 while, the amount of phosphorus loss was 1.34 µg/mm2 and 1.13 µg/mm2 from the teeth exposed to 30% hydrogen peroxide and Opalescence Extra Boost 38% respectively. CONCLUSION: Consecutive bleaching sessions with 30% hydrogen peroxide or Opalescence Extra Boost 38% lead to morphological, microhardness, tensile strength and specific elemental changes when performed repeatedly in a short period of time.