Cytotoxicity of novel fluoride solutions and their influence on mineral loss from enamel exposed to a Streptococcus mutans biofilm.

OBJECTIVE: This study evaluated the cytotoxicity, antimicrobial activity and in vitro influence of new fluoridated nanocomplexes on dental demineralization. DESIGN: The nanocomplexes hydroxypropyl-ß-cyclodextrin with 1% titanium tetrafluoride (TiF4) and γ-cyclodextrin with TiF4 were compared to a positive control (TiF4), a blank control (without treatment) and negative controls (hydroxypropyl-ß-cyclodextrin, γ-cyclodextrin, deionized water), following 12- and 72-hour complexation periods. The cytotoxicity was assessed using the neutral red dye uptake assay at T1-15 min, T2-30 min and T3-24 h. A minimum bactericidal concentration (MBC) against Streptococcus mutans (ATCC 25175) was performed. Enamel blocks were exposed to an S. mutans biofilm, and the percentage of surface microhardness loss was obtained. Biocompatibility and microhardness data were analysed using ANOVA/Tukey tests (p < 0.05). RESULTS: At T1, the cell viability results of the nanocomplexes were similar to that of the blank control. At T2 and T3, the 72 h nanocomplexes demonstrated cell viability results similar to that of the blank, while the 12 h solutions showed results different from that of the blank (p < 0.05). All fluoridated nanocompounds inhibited S. mutans (MBC = 0.25%), while the MBC of TiF4 alone was 0.13%. All fluoridated compounds presented a percentage of surface microhardness loss lower than that of deionized water (p < 0.05). CONCLUSIONS: The new fluoridated nanocomplexes did not induce critical cytotoxic effects during the experimental periods, whilst they did show bactericidal potential against S. mutans and inhibited enamel mineral loss.

Primeiro pré-molar inferior com três canais: relato de caso clínico / First mandibular premolar with three canals: case report

Objetivo: o objetivo deste relato de caso foi descrever o tratamento endodôntico de um primeiro pré-molar inferior com três canais. Relato do caso: paciente do sexo masculino, 54 anos de idade, procurou o serviço de emergência da Universidade Federal do Rio de Janeiro com dor no dente #34. Ao exame clínico/radiográfico, observou-se cárie extensa. O teste de sensibilidade pulpar exibia resposta positiva e exacerbada, com ausência de sintomatologia periapical ao exame de palpação e percussão. Portanto, foi diagnosticado um quadro de pulpite irreversível. O paciente foi anestesiado, realizou-se o isolamento absoluto e a abertura coronária. O preparo mecânico foi realizado com a técnica manual crown-down, sendo o comprimento de trabalho estabelecido a 1 mm aquém do ápice radicular, nos três canais. O hipoclorito de sódio a 2,5% foi usado como solução irrigadora e, para remoção da smear layer, utilizou-se EDTA a 17%. A obturação dos canais radiculares foi realizada pela técnica híbrida de Tagger, utilizando-se o cimento Endofill e cones de guta-percha. A radiografia final exibiu a presença de três canais, um lingual e dois vestibulares, que se encontravam no início do terço apical. Observou-se, ainda, uma ramificação ligando os canais vestibulares (interconduto). Considerações finais: o conhecimento e o domínio da anatomia do canal são fatores chave para o sucesso do tratamento endodôntico.

Influence of a Brazilian wild green propolis on the enamel mineral loss and Streptococcus mutans' count in dental biofilm.

OBJECTIVE: This study investigated the anti-demineralizing and antibacterial effects of a propolis ethanolic extract (EEP) against Streptococcus mutans dental biofilm. DESIGN: Blocks of sound bovine enamel (n=24) were fixed on polystyrene plates. S. mutans inoculum (ATCC 25175) and culture media were added (48 h-37 °C) to form biofilm. Blocks with biofilm received daily treatment (30 µL/1 min), for 5 days, as following: G1 (EEP 33.3%); G2 (chlorhexidine digluconate 0.12%); G3 (ethanol 80%); and G4 (Milli-Q water). G5 and G6 were blocks without biofilm that received only EEP and Milli-Q water, respectively. Final surface hardness was evaluated and the percentage of hardness loss (%HL) was calculated. The EEP extract pH and total solids were determined. S. mutans count was expressed by log10 scale of Colony-Forming Units (CFU/mL). One way ANOVA was used to compare results which differed at a 95% significance level. RESULTS: G2 presented the lowest average %HL value (68.44% ± 12.98) (p=0.010), while G4 presented the highest (90.49% ± 5.38%HL) (p=0.007). G1 showed %HL (84.41% ± 2.77) similar to G3 (87.80% ± 6.89) (p=0.477). Groups G5 and G6 presented %HL=16.11% ± 7.92 and 20.55% ± 10.65; respectively (p=0.952). G1 and G4 differed as regards to S. mutans count: 7.26 ± 0.08 and 8.29 ± 0.17 CFU/mL, respectively (p=0.001). The lowest bacterial count was observed in chlorhexidine group (G2=6.79 ± 0.10 CFU/mL) (p=0.043). There was no difference between S. mutans count of G3 and G4 (p=0.435). The EEP showed pH 4.8 and total soluble solids content=25.9 Brix. CONCLUSION: The EEP seems to be a potent antibacterial substance against S. mutans dental biofilm, but presented no inhibitory action on the de-remineralization of caries process.