Effects of octenidine applied alone or mixed with sodium hypochlorite on eukaryotic cells.

AIM: To assess the effects of octenidine dihydrochloride (OCT) on eukaryotic cells and the cytotoxicity of OCT associated with sodium hypochlorite - NaOCl (NaOCl/OCT). METHODOLOGY: L929 fibroblasts and human osteoblast-like cells (Saos-2) were exposed to 0.1% OCT, 2% CHX, 2.5% NaOCl, 5.25% NaOCl and mixtures of 5.25% NaOCl and 0.1% OCT (NaOCl/OCT) at 90 : 10, 80 : 20 and 50 : 50 ratios. Cell viability was assessed by methyl-thiazol-tetrazolium (MTT) and neutral red (NR) assays; type of cell death, by flow cytometry; cytoskeleton, by actin and α-tubulin fluorescence; and alkaline phosphatase (ALP) activity, by thymolphthalein release. The data were analysed by two-way ANOVA and Bonferroni tests (α = 0.05). RESULTS: MTT and NR assays revealed that 0.1% OCT had the lowest cytotoxicity (P < 0.05), followed by 2% CHX (P < 0.05). The 2.5% NaOCl, NaOCl/OCT 80 : 20 and NaOCl/OCT 50 : 50 solutions had intermediate cytotoxicity. NaOCl 5.25% and NaOCl/OCT 90 : 10 had the highest cytotoxicity (P < 0.05). The OCT group had a higher percentage of viable cells than the NaOCl and CHX groups (P < 0.05), and induced apoptosis at higher doses. The cytoskeleton alterations were observed at 0.12%, 0.6% and 2.02% for the NaOCl, CHX and OCT groups, respectively. The solutions did not induce ALP activity. CONCLUSION: Octenidine dihydrochloride was less cytotoxic, induced apoptosis at higher doses, caused few changes in the cytoskeleton and did not induce alkaline phosphatase activity. In addition, octenidine dihydrochloride reduced the cytotoxicity of 5.25% NaOCl when combined at 20 and 50%.

Penetration of sodium hypochlorite into root canal dentine: effect of surfactants, gel form and passive ultrasonic irrigation.

AIM: To assess the penetration of sodium hypochlorite (NaOCl) gel or NaOCl solutions with surfactants, and the effect of passive ultrasonic irrigation (PUI) on penetration into dentinal tubules. METHODOLOGY: Bovine incisor root canals were instrumented, the roots sectioned and the dentine blocks obtained were stained with crystal violet. Dentine blocks (n = 10 per group) were exposed to 3% NaOCl gel or 3% NaOCl solution for 10 and 20 min. Other dentine blocks (n = 10 per group) were exposed to Chlor-Extra (6% NaOCl + surfactant), 6% NaOCl, 2.5% NaOCl with 0.2% cetrimide and 2.5% NaOCl for 10 and 20 min. The penetration depth of irrigants into dentinal tubules was measured in micrometres by viewing the bleached crystal violet under a stereomicroscope. Additionally, bovine incisor root canals, instrumented and stained with crystal violet, were distributed into two groups (n = 10) and irrigated with 2.5% NaOCl with PUI or conventional syringe irrigation (CSI). The penetration depth of irrigants into dentinal tubules was assessed 3 and 7 mm from the apex. Statistical analysis was performed by ANOVA and Tukey tests (α = 0.05). RESULTS: There was significantly greater penetration of 3% NaOCl solution into dentinal tubules compared with the gel form (P < 0.05). There was no difference (P > 0.05) between 6% NaOCl and Chlor-Extra, and between 2.5% NaOCl and 2.5% NaOCl + cetrimide. PUI significantly increased the penetration depth of NaOCl into dentinal tubules when compared with CSI (P < 0.05). CONCLUSIONS: In extracted bovine incisors, NaOCl gel penetrated less into dentinal tubules than NaOCl solution. The addition of surfactants did not increase the penetration depth. The use of PUI significantly increased NaOCl penetration into dentinal tubules.

Evaluación de la conformación apical de los conductos radiculares con los Sistemas Mtwo y Protaper / Evaluation of the apical conformation of root Canals with Mtwo and ProTaper systems

Objetivo: Evaluar la capacidad de conservar la centricidad a nivel apical de los sistemas rotatorios ProTaper y Mtwo en conductos mesiales de molares inferiores. Metodología: Se emplearon 20 primeros molares inferiores recientemente extraídos con curvaturas superiores a los 20º de acuerdo al método de Schneider. Los especímenes fueron colocados individualmente en muflas de yeso y cubiertos con acrílico de autocurado y se realizaron dos cortes transversales a 1 mm del final del conducto radicular, corte 1 y el otro a 3 mm, corte 2. Un grupo de 20 conductos (G1) se instrumentó con el sistema ProTaper y el otro grupo de 20 conductos (G2) se instrumentó con el sistema Mtwo. La calidad de cada sistema para permanecer centrado en el conducto radicular fue determinada mediante el cálculo del cociente de centricidad. Resultados: Se evaluó el cociente de centricidad, mediante un análisis de varianza, que en valores absolutos, mostró diferencias significativas entre ambos métodos para ambos cortes, siendo el sistema Mtwo más eficiente en ambos casos que el Protaper (p<0,01). Conclusiones: Debido a que los dos sistemas se pueden atribuir a la técnica de instrumentación empleada y/o a las diferencias en el diseño de cada uno de ellos. Bajo las condiciones de este estudio ninguno de los dos sistemas respetó escrupulosamente la centricidad del conducto radicular mostrando Mtwo un mejor comportamiento que ProTaper (AU)

Aim: To assess the ability to preserve the centricity at apical level of the ProTaper and Mtwo rotatory systems in mesial canals of mandibular molars. Methodology: A total of twenty mesial roots from freshly mandibular first molars with two canals for each one and curvatures higher than 20º according to Schneider method were used. The specimens were place in gypsum muffle and then were covered with acrylic. Two cross-sections were perfomerd, the first one at 1 mm and the second one at 3 mm form the end of the radicular canal. The root were divided in two groups of 20 canals each one: Group 1(G1) was instrumented with ProTaper System and group 2 (G2) was instrumented with Mtwo System. The ability to maintain the centrality of each system was determined by the centricity ratio calculus. Results: The centricity ratio was evaluated through an analysis of variance that in absolute values showed significant defferences between the two methods in both cross-sections, being Mtwo system more efficient than Pro Taper system (p<0,01). Conclusions: Because the two instrumentation systems compared are manufactured by a similar alloy, the behavioral differences between each system can be attributed to the instrumentation technique used and/or to differences in the design of each one of them. Under the conditions of this study none of the two systems scrupulously respected the centricity of the canal showing Mtwo a better performance than ProTaper (AU)