Antibacterial activity of intracanal medications based on calcium hydroxide and zinc oxide micro- or nanoparticles: an ex vivo study / Atividade antibacteriana de medicações intracanal à base de hidróxido de cálcio e óxido de zinco micro- e nanoparticulado: estudo ex vivo

Introduction: Nanoparticles and associations to calcium hydroxide can be used to increase antimicrobial activity. Objective: To evaluate antibacterial activity against Enterococcus faecalis and pH of intracanal medications (IM) based on calcium hydroxide (CH) and zinc oxide (ZnO) micro- or nanoparticles, and their association with 0.4% chlorhexidine (CHX). Material and method: Root canals from single-rooted human teeth were inoculated and incubated for 21 days. After sample (S1), the root canals were filled with the medications for 7 days and samples were collected immediately after medication (S2) and 7 days later (S3). Counting of CFU mL-1 was performed. Polyethylene tubes filled with the medications were used for the pH evaluation after 3, 7, 14 and 28 days. Data were submitted to ANOVA and Tukey tests (p<0.05). Result: All IM promoted elimination of E. faecalis immediately after medication (S2). All the pastes promoted a similar pH increase. Conclusion: CH/ZnO micro- or nanoparticles associated with CHX promoted greater bacterial reduction in the root canals and similar pH.

Introdução: Nanopartículas e associações ao hidróxido de cálcio podem ser usados para aumentar a ação antimicrobiana. Objetivo: Avaliar a atividade antibacteriana sobre Enterococcus faecalis e o pH de medicações intracanal (MI) à base de hidróxido de cálcio (HC) e óxido de zinco (OZn) micro- e nanoparticulado, e suas associações com clorexidina (CHX) a 0,4%. Material e método: Canais radiculares de dentes humanos unirradiculados foram inoculados e incubados por 21 dias. Após coleta (C1), os canais radiculares foram preenchidos com os medicamentos durante 7 dias e as amostras foram coletadas imediatamente após a medicação (C2) e 7 dias depois (C3). Contagem de UFC mL-1 foi realizada. Os tubos de polietileno preenchidos com os medicamentos foram utilizados para a avaliação do pH após 3, 7, 14 e 28 dias. Os dados foram submetidos aos testes de ANOVA e Tukey (p<0,05). Resultado: Todas as MI promoveram eliminação de E. faecalis imediatamente após a medicação (C2). Todas as pastas promoveram similar aumento de pH. Conclusão: HC/OZn micro- ou nanoparticulado associado com CHX promove maior redução bacteriana nos canais radiculares e pH similar.

Effect of addition of nano-hydroxyapatite on physico-chemical and antibiofilm properties of calcium silicate cements

ABSTRACT Objective Mineral Trioxide Aggregate (MTA) is a calcium silicate cement composed of Portland cement (PC) and bismuth oxide. Hydroxyapatite has been incorporated to enhance mechanical and biological properties of dental materials. This study evaluated physicochemical and mechanical properties and antibiofilm activity of MTA and PC associated with zirconium oxide (ZrO2) and hydroxyapatite nanoparticles (HAn). Material and Methods White MTA (Angelus, Brazil); PC (70%)+ZrO2 (30%); PC (60%)+ZrO2 (30%)+HAn (10%); PC (50%)+ZrO2 (30%)+HAn (20%) were evaluated. The pH was assessed by a digital pH-meter and solubility by mass loss. Setting time was evaluated by using Gilmore needles. Compressive strength was analyzed by mechanical test. Samples were radiographed alongside an aluminum step wedge to evaluate radiopacity. For the antibiofilm evaluation, materials were placed in direct contact with E. faecalis biofilm induced on dentine blocks. The number of colony-forming units (CFU mL-1) in the remaining biolfilm was evaluated. The results were submitted to ANOVA and the Tukey test, with 5% significance. Results There was no difference in pH levels of PC+ZrO2, PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p>0.05) and these cements presented higher pH levels than MTA (p<0.05). The highest solubility was observed in PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p<0.05). MTA had the shortest initial setting time (p<0.05). All the materials showed radiopacity higher than 3 mmAl. PC+ZrO2 and MTA had the highest compressive strength (p<0.05). Materials did not completely neutralize the bacterial biofilm, but the association with HAn provided greater bacterial reduction than MTA and PC+ZrO2 (p<0.05) after the post-manipulation period of 2 days. Conclusions The addition of HAn to PC associated with ZrO2 harmed the compressive strength and solubility. On the other hand, HAn did not change the pH and the initial setting time, but improved the radiopacity (HAn 10%), the final setting time and the E. faecalis antibiofilm activity of the cement.

Radiopacity and cytotoxicity of Portland cement associated with niobium oxide micro and nanoparticles

Objective Mineral Trioxide Aggregate (MTA) is composed of Portland Cement (PC) and bismuth oxide (BO). Replacing BO for niobium oxide (NbO) microparticles (Nbµ) or nanoparticles (Nbη) may improve radiopacity and bioactivity. The aim of this study was to evaluate the radiopacity and cytotoxicity of the materials: 1) PC; 2) White MTA; 3) PC+30% Nbµ; 4) PC+30% Nbη. Material and Methods For the radiopacity test, specimens of the different materials were radiographed along an aluminum step-wedge. For cell culture assays, Saos-2 osteoblastic-cells (ATCC HTB-85) were used. Cell viability was evaluated through MTT assay, and bioactivity was assessed by alkaline phosphatase activity assay. Results The results demonstrated higher radiopacity for MTA, followed by Nbµ and Nbη, which had similar values. Cell culture analysis showed that PC and PC+NbO associations promoted greater cell viability than MTA. Conclusions It was concluded that the combination of PC+NbO is a potential alternative for composition of MTA. .