Effect of zinc oxide-eugenol endodontic paste on planktonic aggregates and biofilm of Enterococcus faecalis - An atomic force microscopy evaluation.

OBJECTIVE: This work aimed to evaluate the in vitro effect of zinc oxide-eugenol paste (ZOE) on planktonic aggregates (EfPA) and biofilm (EfBio) of Enterococcus faecalis, focusing on their morphological aspects observed and analyzed using atomic force microscopy (AFM). DESIGN: The eugenol and paste were characterized by Gas Chromatography coupled with Mass Spectrometry (GC-MS) and Fourier Transform Infrared Spectroscopy (FTIR), respectively. The effect of ZOE on EfPA and EfBio was evaluated by a direct-contact test through colony counting and crystal violet staining protocol. AFM images of untreated and treated EfPA and EfBio growth on bovine dentin were obtained to analyze the morphological damage caused by the treatments. RESULTS: The characterization showed high purity in the eugenol composition and chemical interaction between the components of the paste. A bactericidal effect on aggregates was observed after 6 h of exposure, and on biofilm after 24 h of treatment (p < 0.001). A disruptive effect on the biofilm was also evident. AFM images revealed the formation of EfPA, with a notable presence of an exopolysaccharide matrix. After 6 h of ZOE treatment, there was a significant increase in the size and surface roughness profile of treated cells (p < 0.05). Loss of typical cell morphology was observed after 24 h. The effect on the biofilm showed a tendency towards a less condensed biofilm pattern in the treated group, with no differences in surface roughness. CONCLUSION: ZOE presents bactericidal action on EfPA and EfBio, promoting significant morphological changes after treatment, especially in the aggregates.

Avaliação da Dureza de Materiais Restauradores Diretos Submetidos a Diferentes Desafios Erosivos / Hardness Evaluation of Direct Restorative Materials Submitted to Different Erosive Challenges

Objetivo: Avaliar a dureza de materiais restauradores diretos submetidos a diferentes desafios erosivos in vitro. Material e método: Trata-se de um estudo experimental realizado com 12 amostras de cada material restaurador medindo 4 mm de diâmetro x 2 mm de espessura. As amostras de resinas (microparticulada e nanoparticulada) e dos cimentos de ionômero de vidro (convencional e modificado por resina) foram confeccionadas e a dureza de superfície foi determinada antes e após uma semana de desafio erosivo, sendo a troca dos meios realizada a cada 24 horas. A análise Estatística dos dados foi feita por ANOVA de 2 fatores. O Teste t pareado avaliou a comparação entre as durezas iniciais e finais. Os testes estatísticos foram realizados pelo Programa Minitab (versão 17) com o nível de significância fixado em 5%. Resultados e Conclusão: Os resultados mostram que cimento de ionômero de vidro convencional e resina nanoparticulada apresentaram maiores valores de perda de dureza. Quantos aos meios, a Coca-Cola ocasionou maior perda de dureza no Cimento de ionômero de vidro convencional e o Powerade provocou maior grau de erosão no Cimento de ionômero de vidro modificado por resina. Todos os materiais testados apresentaram redução na dureza da superfície como resultado do desafio erosivo em bebidas ácidas, sendo o cimento de ionômero de vidro convencional o material mais afetado.

Objective: To evaluate in vitro the hardness of restorative materials submitted to different erosion challenges. Material and method: This was an experimental study using 12 samples of each restorative material measuring 4 mm diameter x 2 mm thick. Resins samples (microparticulate and nanoparticulate) and glass ionomer cements (conventional and resin-modified) were prepared and the surface hardness was determined before and after a week of erosive challenge, with the media being changed at each 24 hours. The statistical analysis was performed by two-way-ANOVA. The paired t test evaluated the comparison between the initial and final hardness. Statistical tests were performed with Minitab Program (version 17) and the significance level was set at 5%. Results and Conclusion: Conventional glass ionomer cement and nanoparticulate resin had higher hardness loss values. Regarding the beverages, Coca-Cola caused higher hardness loss in the conventional glass ionomer cement and Powerade lead to a higher degree of erosion in the glass ionomer cement modified by resin. Conclusion: All materials tested showed reduction in surface hardness as a result of erosive challenge in acidic drinks. Conventional glass ionomer cement was the most affected material.

Total Fluoride Intake by Children from a Tropical Brazilian City.

The main sources of fluoride intake by children are fluoridated water and toothpaste. Little has been studied regarding fluoride intake from these sources in regions with tropical climates and high temperatures throughout the year. This study aimed to determine the amount of fluoride ingested from diet and tooth brushing by children who live in a city with a tropical climate. Sixty-seven children from Teresina, Piauí, Brazil, took part in this study. The city's water supply was optimally fluoridated. The duplicate-diet method was used to determine the fluoride intake from diet. The intake of fluoride from dentifrice was determined by subtracting the amount of fluoride placed on the toothbrush and that recovered after brushing. The concentration of fluoride was measured using an ion-specific electrode and is expressed as milligrams/kilogram of body weight/day. The mean (±SD) total amount was 0.071 ± 0.036 mg F/kg body weight/day, and the relative contributions of diet and toothpaste were 0.025 ± 0.010 and 0.046 ± 0.035, respectively. The factors associated with fluoride intake from toothpaste were: use of children's toothpaste (p = 0.003), use of large amounts of toothpaste (p < 0.001), and a high frequency of tooth brushing (p = 0.003). Sixty-four percent of children had an intake of less than 0.07 mg F/kg body weight/day, which is considered the upper limit for an aesthetically tolerable fluorosis risk. The results suggest that the amount of fluoride ingested by most children who live in a Brazilian city with a tropical climate is considered safe in terms of the risk of dental fluorosis.