engleski

Enamel and dentin microhardness and chemical composition after experimental light-activated bleaching

Objectives were tTo evaluate the influence of five bleaching agents with additional light activation on enamel and dentin surface microhardness and chemical composition, as well as the remineralizing potential of artificial saliva and amorphous calcium phosphate (ACP). The study was conducted on 125 human third molars dissected into quarters for separate enamel and dentin measurements. Bleaching process was performed with 38% and 25% hydrogen peroxide (HP) and 30%, 16% and 10% carbamide peroxide (CP) gels for 2×15 minutes. All bleaching gels were tested alone and in combination with ZOOM2, light emitting diode (LED), organic LED and femtosecond laser. A total of 25 bleaching combinations (n=10) were evaluated. Microhardness was measured by Vickers diamond. Chemical analysis was performed using energy-dispersive X-ray spectroscopy. Bleaching agents, without light activation, caused a significant reduction of enamel and dentin surface microhardness (p<0.001), ranging from 8% for 16% CP to 40% for 25% HP. The effects of different light activations were negligible. After two-week treatment with ACP and artificial saliva, maximum deviation from baseline microhardness was just 3%. Such treatment increased concentrations of calcium, phosphorus and fluorine. Increase in peroxide concentration and gel acidity negatively affected microhardness and concentrations of calcium and phosphorus in enamel and dentin. ACP and artificial saliva stimulated the remineralization of hard tissues. The bleaching lights could be safely used regarding enamel and dentin microhardness and chemical composition. Adverse effects of peroxide concentration and gel acidity could be restored after two-week ACP and artificial saliva treatment.

Bleaching ; Microhardness ; Microstructure ; Photostimulation ; Amorphous calcium phosphate

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