Influence of application time of antioxidant on the deproteinized dentin: a SEM/EDS study/Utjecaj duljine primjene antioksidanta na deproteinizirani dentin: istrazivanje SEM/EDS-om

Objective: To evaluate in vitro the influence of application time of sodium ascorbate to 10% on the deproteinized by scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS). Methods: Seven extracted human third molars were selected. For analysis of the composition of the dentin surface by SEM/EDS, 7 samples were analyzed simultaneously as follows: G1: Healthy dentin substrate, G2: Demineralized dentin substrate with 37% phosphoric acid for 15 s (demineralization), strictly following the manufacturer's recommendations, G3: Deproteinized dentin substrate after demineralization, 10% sodium hypochlorite aqueous solution for 60 s under constant agitation (deproteinization), G4, G5, G6 and G7: demineralized, deproteinized dentin substrate after application of 10% sodium ascorbate for 15 s, 30 s, 60 s, 10 min, respectively. The samples were examined by a scanning electron microscope (Quanta 2000--Fei Company) equipped with an energy dispersive spectrometer with acceleration voltage 10 KV at *2,000 magnification under vacuum. Results: The SEM/EDS analysis showed progressive deposition of sodium ascorbate crystals as the application time of the antioxidant agent increased, forming crusts which can cause occlusion of some dentinal tubules. There was no statistically significant difference between G2 and G3 (P>0.05). However, the application of 10% sodium ascorbate for 60 s resulted in a decrease in the oxygen (P=0.029), magnesium (P=0.019) and sodium (P=0.029) levels. Conclusion: After application of 10% sodium ascorbate, deposition of sodium ascorbate crystals occurred progressively forming crusts on dentin substrate, which causes occlusion of some dentinal tubules. Key words Dentin; Antioxidants; Ascorbic Acid; Microscopy, Electron, Scanning; Spectrometry, X-Ray Emission Svrha: U uvjetima in vitro zeljelo se procijeniti utjece li i kako primjena 20-postotnog natrijeva askorbata na deproteinizirani dentin, a za to se rabio elektronski mikroskop/rendgenska spektroskopija rasprsivanja energije (SEM/EDS). Materijal i metode: Sedam ekstrahiranih humanih trecih kutnjaka odabrano je za istodobnu analizu sastava i dentinske povrsine uz pomoc SEM/ EDS-a. Bilo je odabrano i poduzeto sljedece: G1--zdrav dentinski supsrat; G2--demineralizirani dentinski supstrat demineraliziran 15 sekundi 37-postotnom ortofosfornom kiselinom prema uputi proizvodaca; G3--deproteinizirani dentinski supstrat deproteiniziran 60 sekundi uz neprekidno mijesanje u 10-postotnoj vo