engleski

Surface changes of enamel and dentine after two different bleaching procedures

Purpose: Bleaching agents have effect on chemical / physical and morphological structure of enamel and dentine that must be taken into account when this therapy is used. The aim of this in vitro study was to evaluate the effects of two bleaching agents containing high concentration of hydrogen peroxide for professional use on human enamel and dentine surface and to evaluate the potential remineralizing effect of amorphous calcium phosphate gel (ACP). Materials and methods: Twenty five human third molars were divided into two groups and disected in half and both surfaces were bleached with either ZOOM2 or Opalesence BOOST for 3×15 minutes. Vickers microhardness of enamel and dentine was measured before, after the bleaching treatment and after treatment with artificial saliva and ACP gel or 2 weeks storage in deionized water. Surface microstructure was evaluated using SEM. Mixed model ANOVA and Wilcoxon Rank Sum test were used. Results: Both bleaching agents showed significant reduction in surface microhardness (p<0.001 for both BOOST and ZOOM2 application). ZOOM2 which had the lower pH value showed larger decrease in surface microhardness (p=0.005) compared to BOOST. Post-treatment with artificial saliva and ACP showed significant increase in surface microhardness (p<0.001). After the bleaching procedure enamel and dentine surface microstructure showed mild or slight alterations with no loss of superficial structure. Conclusion: Both bleaching agents resulted in a reduction in surface enamel and dentine microhardness. Treatment with ACP demonstrated the increase in surface microhardness, improved surface roughnes and enhance the remineralization of the hard dental tissues.

Light activated bleaching ; Microhardness ; Microstructure ; Amorphous calcium phosphate

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