LETICIA CRISTINA CIDREIRA BOARO
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Artigo IPEN-doc 25707 Antibacterial resin-based composite containing chlorhexidine for dental applications2019 - BOARO, LETICIA C.C.; CAMPOS, LUIZA M.; VARCA, GUSTAVO H.C.; SANTOS, TAMIRIS M.R. dos; MARQUES, PAMELA A.; SUGII, MARI M.; SALDANHA, NATHALIA R.; COGO-MULLER, KARINA; BRANDT, WILLIAM C.; BRAGA, ROBERTO R.; PARRA, DUCLERC F.Objeticve. The aim of this study was to develop a composite material with antibacterial activ-ity using MMT loaded with clorhexidine (CHX). For that it was used a BisGMA/TEGDMAmatrix and added low concentration of MMT/CHX. The aim was to evaluate the drug releasecapacity of MMT, and not to provide reinforcement.Methods. Six experimental composites were made with organic matrix of BisGMA/TEGDMAin equal proportions by weight. The composites received organophlizated montmorillonitewith or without CHX. The concentrations were 2,5; 5 or 10% by weight. Degree of conversion(DC) was evaluated using FTIR (peak 6165 cm-1; n = 5). Specimens for flexural properties(10×2×1 mm) were immediate tested (24h). Elastic modulus(E) and flexural strength (FS)was measured using the three point bending test (n = 10). Inibition halo was used to test theantibacterial activity against Staphylococcus aureus, Streptococcus mutans, and Porphyromonasgingivalis (n = 5 for each bacteria). The inhibition of biofilm formation (BF) was evaluated byinserting polymerized disc of composite in to a culture media colonized with Streptococcusmutans (n = 10). The release of CHX was measured using ultraviolet (255 nm) for 10 days(n = 5). The data of degree of conversion was analysed using Kruskal–Wallis/ Mann–Whitney,and the other variables using two-way ANOVA/Tukey, always considering a global level ofsignificance of 5%.Results. DC ranged from 71% to 74%. E ranged from 5.7 to 8.1 GPa. FS ranged from 61.4 to74.7 MPa. There were no statistical differences among the groups for all the variables. Forthe three bacteria tested the composites with CHX loaded presented inhibition of growthfor all concentration, except for 2,5% that did not inihibited the growth of P. gingivalis. BFwas lower for the groups with 10% MMT/CHX, all groups presented BF, even those withoutCHX loaded. All concentrations presented release off CHX during all the 28 days analyzed. Conclusions. Within the limitation of this study it can be concluded that: all concentrations tested presented release of CHX and reduced BF. All concentration presented antibacterial activity for the three bacteria tested, except for 2,5% that did not inhibit the growth of P. gingivalis. The presence of MMT with CHX loaded did not interfere in the properties evaluated.Artigo IPEN-doc 22624 Chlorhexidine loaded MMT as dental composite filler: release evaluation2016 - CAMPOS, LUIZA M.; BOARO, LETICIA C.; SANTOS, TAMIRIS R.; SANTOS, VINICIUS J.; VARCA, GUSTAVO C.; PARRA, DUCLERC F.Polymeric restorative materials are widely used, however polymerization shrinkage still stands as a major drawback as it allows microleakage, secondary caries, postoperative sensitivity and cusp deflection. A polymeric material with antimicrobial activity could be very useful in many dental procedures including adhesive cementation, sealants, dental adhesives and direct restorative material. The aim of this study was to develop nanocomposites for dental purposes composed by chlorhexidine loaded montmorillonite (Cloisite 30B) nanoparticles in a BisGMA / TEGDMA organic matrix. The specimens of experimental composites were synthesized with 10 % (w/w) of diacetate chlorhexidine incorporated in a MMT, as filler. The chlorhexidine release at 37 oC was evaluated in vitro in physiological solution at neutral pH for 366 hours. Drug content was estimated by UV spectroscopy at λ=255 nm. Significant drug release initiated after 96 hours and maintained throughout the experiment. In conclusion, the composite was capable of promoting chlorhexidine release over time, and such results in addition to the lack of significant weight loss (≤ 1.43 %) and the very low swelling (≤ 2.22 %) properties, revealed the strong potential of the developed composite for further dental and other biomaterial applications.