Abstract Objective: To investigate the use of polymethyl methacrylate (PMMA) electrospun fiber mats containing different amounts of polyethylene oxide (PEO) as a doxycycline delivery system and to test antibacterial activity against an oral pathogen. Methodology: PMMA powders or PEO (mol wt 200 Kd) (10,20,30% w/w/) were dissolved in N, N-dimethylformamide (DMF) to obtain a final polymer concentration of 15% in DMF (w/v). 2% Doxycycline monohydrate was added to the solutions and submitted to vortex mixing. The solution was transferred to a plastic syringe and fit into a nanofiber electrospinning unit. The parameters applied were: voltage at 17.2 kV; distance of 20 cm between the needle tip and the collector plate; target speed at 2 m/min; and transverse speed at 1cm/min. Syringe pump speed was 0.15 mm/min. The drug release analysis was performed by removing aliquots of the drug-containing solution (in PBS) at specific periods. Doxycycline release was quantified using RP-HPLC. Fiber mats from all groups had their antibacterial action tested against S. mutans based on inhibition halos formed around the specimens. The experiments were performed in triplicate. Gravimetric analysis at specific periods was performed to determine any polymer loss. Morphological characterization of the electrospun fibers was completed under an optical microscope followed by SEM analysis. Results: The addition of PEO to the PMMA fibers did not affect the appearance and diameter of fibers. However, increasing the %PEO caused higher doxycycline release in the first 24 h. Fibers containing 30% PEO showed statistically significant higher release when compared with the other groups. Doxycycline released from the fibers containing 20% or 30% of PEO showed effective against S. mutans. Conclusion: The incorporation of PEO at 20% and 30% into PMMA fiber mat resulted in effective drug release systems, with detected antibacterial activity against S. mutans.

Resumo Este estudo avaliou o pH, radiopacidade, efeito antimicrobiano, citotoxicidade e biocompatibilidae de materiais obturadores de dentes decíduos. Foram avaliados o cimento de óxido de zinco e eugenol (OZE), Vitapex e pasta Calen espessada com óxido de zinco (OZ), comparativamente a um material experimental à base de MTA. A radiopacidade foi testada usando uma escala milimetrada de alumínio, com um sensor digital. O pH dos materiais também foi avaliado nos períodos de 1, 4, 12 h; 1, 3, 7, 15, e 30 dias (n=5). O teste de contato direto foi utilizado para avaliação da atividade antimicrobiana dos materiais conta uma cepa de Enterococcus faecalis após incubação por 1, 4, 12, e 24 h (n=5). Para avaliação da citotoxicidade foi utilizado o teste de MTT para avaliação da viabilidade celular. No teste de biocompatibilidade, ratos Wistar receberam implantes subcutâneos contendo cada material obturador (n=5). Após biópsia, os tecidos foram submetidos à avaliação histológica em períodos de 15, 30 e 60 dias. Os resultados de radiopacidade, pH, ação antimicrobiana e citotoxicidade foram analisados usando os testes ANOVA e Tukey. Os dados histológicos foram submetidos ao teste de Kruskal-Wallis. O material experimental apresentou a menor radiopacidade (3.28 mm Al) e apresentou um pH superior a 12,0 durante todo o período experimental. O material experimental apresentou o maior efeito antimicrobiano, eliminando mais de 99,97% das bactérias em um período de 4 h. O Vitapex permitiu uma maior viabilidade celular em comparação aos demais materiais avaliados. Inicialmente, os testes de biocompatibilidade demonstraram inflamação de moderada a severa em todos os grupos. Após 60 dias, apenas o grupo Calen+ OZ apresentou inflamação moderada, enquanto os outros materiais demonstraram predominantemente a indução de inflamação leve. Os resultados demonstraram que o material experimental à base de MTA exibiu comportamento satisfatório com relação às propriedades avaliadas. Estudos adicionais, in vivo, são necessários para uma melhor avaliação do material.

Abstract This study assessed the pH, radiopacity, antimicrobial effect, cytotoxicity and biocompatibility of endodontic filling materials for primary teeth. Zinc oxide eugenol (ZOE), Vitapex and Calen paste thickened with zinc oxide (ZO) were evaluated in comparison to an experimental MTA-based material. Radiopacity was tested using a graduated aluminum stepwedge with a digital sensor (n=5). The materials pH was recorded at 1, 4, 12 h; 1, 3, 7, 15 and 30 days (n=5). Direct contact test was used to assess the antimicrobial efficacy against Enterococcus faecalis after 1, 4, 12, 24 h (n=5). Cytotoxicity assay used MTT test for cell viability after incubation for 1, 3 and 7 days (n=5). For biocompatibility test, Wistar rats had received implants containing each material (n=5). The biopsied tissues were histologically analyzed after 15, 30 and 60 days. The results of radiopacity, pH, antimicrobial capacity and cytotoxicity were analyzed using ANOVA and Tukey tests. The histological data were submitted to Kruskal-Wallis test. The experimental material presented the lowest radiopacity (3.28 mm Al) and had a pH>12.0 throughout the test period. The experimental material showed the highest antibacterial effect, killing over 99.97% bacteria in 4 h. Vitapex presented the highest cell viability. Initially, biocompatibility test showed moderate to severe inflammation in all groups. After 60 days, Calen+ZO group showed moderate inflammation, while the others showed predominantly mild inflammatory reaction. The present results demonstrated that the experimental MTA-based material exhibited satisfactory behavior regarding the studied properties. Additional in vivo studies are necessary for a better evaluation of the material.