Abstract: This in vitro study aimed to assess the effects of different pretreatments used to adapt glass-fiber posts cemented to root canals with different resin cements, regarding porosity percentage and bond strength. Twelve bovine incisor roots were prepared with Largo drills. After post space preparation, the specimens were randomized into two types of pretreatment groups (n = 3): water-wet bonding and ethanol-wet bonding. After the post were cemented, the roots were stored in 100% humidity at room temperature for 7 days. The samples were scanned by microcomputed tomography (micro-CT). Images were reconstructed by NRecon software, and CTAn software was used to analyze the porosity percentage (%) at the luting interface. Evaluation of the push-out bond strength was performed by serially cutting the roots, and submitting the slices to testing. Additionally, the resin cement post-gel shrinkage values (%) were measured using the strain-gauge method (n = 10). Data were analyzed by two-way ANOVA, Tukey's test and Student's t test (a = 0.05). The roots prepared with ethanol-wet bonding using RelyX™ U200 had significantly lower porosity in the coronal and apical thirds (p < 0.05). The group prepared with ethanol-wet bonding using RelyX™ ARC presented better bond strength results in the coronal and apical thirds (p < 0.05). RelyX™ ARC (0.97%) produced a higher post-gel shrinkage value than RelyX™ U200 (0.77%). Canals pretreated with ethanol-wet bonding presented better outcomes in regard to porosity percentage and push-out bond strength.

RESUMO Objetivo: Investigar a ação do fluoreto de sódio à 2% como um novo método de desinfecção/esterilização de dentes humanos extraídos, usando E. faecalis. Métodos: A taxa de sobrevivência do E. faecalis ATCC 29212 foram avaliadas, em termos de absorbância a partir do meio de cultura, usando espectofotômetro. A avaliação de esterilização ocorreu de acordo com os seguintes grupos: Grupo I (GI) - controle; GII - autoclave; GIII - fluoreto de sódio 7 dias; GIV - fluoreto de sódio 14 dias. Resultados: Quando utilizado autoclave e solução de fluoreto de sódio (2%), a quantidade de bactérias foi reduzida significativamente quando comparado com o grupo de controle (p <0.001). Diferenças estatisticamente significantes também foram encontrados quando os grupos experimentais foram comparados uns com os outros (p < 0.001). Conclusão: Os resultados do presente estudo sugerem que a solução de fluoreto de sódio à 2% pode ser considerado como um novo método de desinfecção com base na sua capacidade para reduzir a carga de E. faecalis.

ABSTRACT Objective: Investigate the action of sodium fluoride 2% as a new method of disinfecting/sterilizing extracted human teeth, using E. faecalis. Methods: The survival rate of E. faecalis ATCC 29212 was assessed, in terms of absorbance from the culture media, using a spectrophotometer. The sterilization assessment was carried out in the following groups: Group I (GI) - control; GII - autoclave; GIII - sodium fluoride seven days; GIV - sodium fluoride 14 days. Results: When using the autoclave and sodium fluoride solution (2%), the quantity of bacteria reduced significantly when compared to the control group (p <0.001). Statistically significant differences were also found when the experimental groups were compared with each other (p < 0.001). Conclusion: The results of the present study suggest that sodium fluoride 2% solution can be considered a new disinfection method based on its capacity to reduce the load of E. faecalis.