Use of nanoparticulate zinc oxide as intracanal medication in endodontics: pH and antimicrobial activity

The aim of this study was to evaluate the pH and antimicrobial activity of micro or nanoparticulate zinc oxide (ZnO) pastes with or without calcium hydroxide (CH). The following medications were evaluated: microparticulate ZnO + polyethylene glycol (PEG) 400; nanoparticulate ZnO + PEG 400; PEG 400; CH + microparticulate ZnO + PEG 400 and CH + nanoparticulate ZnO + PEG 400. The pH was assessed between 12 hours and 28 days, using a digital pH meter. The antimicrobial activity against Enterococcus faecalis (ATCC-9212), Candida albicans (ATCC-10231), Pseudomonas aeruginosa (ATCC-27853), Staphylococcus aureus (ATCC-6538) and Kocuria rhizophila (ATCC-9341) was determined in triplicate using agar diffusion test. The results were submitted to Kruskal-Wallis/Dunn and ANOVA/Tukey tests with 5% significance. The highest pH values were found for CH+ZnO, with higher values for nanoparticulate ZnO after 12 hours and 21 days (p<0.05). CH+ZnO medication promoted higher growth inhibition against P. aeruginosa and lower against E. faecalis. Calcium hydroxide pastes have higher pH and antimicrobial activity when associated with either micro- or nanoparticulate zinc oxide.

O objetivo do estudo foi avaliar o pH e atividade antimicrobiana de pastas de oxido de zinco micro ou nanoparticulado (OZn) com ou sem hidroxido de calcio (HC). As medicacoes avaliadas foram OZn microparticulado + polietilenoglicol (PLG) 400; OZn nanoparticulado + PLG 400; PLG 400; HC + OZn microparticulado + PLG 400 e HC + OZn nanoparticulado + PLG 400. A analise do pH foi realizada entre 12 horas e 28 dias, usando um pHmetro digital. A atividade antimicrobiana frente Enterococcus faecalis (ATCC-9212), Candida albicans (ATCC-10231), Pseudomonas aeruginosa (ATCC-27853), Staphylococcus aureus (ATCC-6538) e Kocuria rhizophila (ATCC-9341) foi determinada, em triplicata, pelo teste de difusao em agar. Os resultados submetidos ao teste Kruskal-Wallis e Dunn e ANOVA e Tukey com 5% de significancia. Os maiores valores de pH ocorreram para HC+ZnO, sendo maior para ZnO nanoparticulado apos 12 horas e 21 dias (p<0,05). A medicacao de HC+ZnO promoveu maior inibicao de crescimento sobre P. aeruginosa e menor sobre E. faecalis. As pastas de hidroxido de calico apresentam os maiores valores de pH atividade antimicrobiana com a associacao de oxido de zinco micro ou nanoparticulado.