The evaluation of cytotoxicity and cytokine IL-6 production of root canal sealers with and without the incorporation of simvastatin: an invitro study.

BACKGROUND: Freshly mixed root canal sealers when proximate the periapical tissues, trigger varying degrees of cytotoxicity/inflammatory reactions. Simvastatin, a class of the drug statin, is a widely used cholesterol-lowering agent with additional anti-inflammatory activities. This study assessed the effects of simvastatin on cytotoxicity and the release of IL-6 (Interleukin-6) production when incorporated in zinc oxide eugenol and methacrylate resin-based sealers. METHODS: Experimental groups consisted of conventional zinc oxide eugenol and methacrylate based-EndoREZ sealers (ZE & ER respectively) and 0.5 mg/mL simvastatin incorporated sealers (ZES & ERS). L929 mouse fibroblast cells were exposed to freshly mixed experimental sealers and evaluated for cytotoxicity (MTT assay) and inflammation levels (inflammatory marker IL-6 for ELISA) at various time intervals (0h, 24h and 7th day). The values were compared to the cell control (CC; L929 cells alone) and solvent control (SC; L929 cells + DMSO) groups. All the experiments were conducted in triplicates and subjected to statistical analysis using IBM SPSS Statistics software. Non parametric tests were conducted using Kruskal-Wallis and Friedman tests for inter-group and intra-group comparisons respectively. Pairwise comparison was conducted by post hoc Dunn test followed by Bonferroni correction. P values < 0.05 were considered statistically significant. RESULTS: All the experimental groups (ZE, ER, ZES, ERS) exhibited varying degree of cytotoxicity and IL-6 expression compared to the control groups CC and SC. The cell viability for ZE and ER decreased on day 7 as compared to 24 h. ZES and ERS had higher viable cells (75.93% & 79.90%) compared to ZE and ER (54.39% & 57.84%) at all time periods. Increased expression of IL-6 was observed in ZE & ER (25.49 pg/mL & 23.14 pg/mL) when compared to simvastatin incorporated ZE & ER (ZES-12.70 pg/mL & ERS-14.68 pg/mL) at all time periods. Highest level of cytotoxicity and inflammation was observed in ZE compared to all the other groups on day 7. CONCLUSIONS: Addition of 0.5 mg/mL of simvastatin to the sealers (ZES and ERS) decreased the cytotoxicity in the freshly mixed state and reduces their inflammatory effect.

An in vitro evaluation of the effect of deep dry cryotreatment on the cutting efficiency of three rotary nickel titanium instruments.

CONTEXT: Cryogenic methods have been used to increase the strength of metals. AIM: The aim of this study was to evaluate the effect of deep dry cryotherapy on the cyclic fatigue resistance of rotary nickel titanium instruments. MATERIALS AND METHODS: Twenty K3, RaCe and Hero Shaper nickel titanium instruments, size 25, 0.06 taper, were taken for this study. Ten files were untreated (control group) and 10 files were deep dry cryogenically treated. Both the untreated and cryotreated files were subjected to cyclic fatigue evaluation. Cyclic fatigue was evaluated as the number of cycles it took for fracture of the instrument within a stainless steel shaping block of specific radius and angle of curvature. STATISTICAL ANALYSIS: Mean values were compared between different study groups by using one-way analysis of variance (ANOVA) with P < 0.05 considered as the level of significance. RESULTS: The results showed a significant increase in the resistance to cyclic fatigue of deep dry cryotreated NiTi files over untreated files. CONCLUSIONS: It may thus be concluded that deep cryotherapy has improved the cyclic fatigue of NiTi rotary endodontic files.

Duration-dependent susceptibility of endodontic pathogens to calcium hydroxide and chlorhexidene gel used as intracanal medicament: an in vitro evaluation.

The aim of this study was to evaluate the effective duration of antimicrobial activity of a calcium hydroxide-based medicament (Apex Cal) and 2% chlorhexidene gluconate gel against selected endodontic pathogens (Enterococcus faecalis, Candida albicans, Porphyromonas gingivalis, and Prevotella intermedia). The agar diffusion test was used to determine the antimicrobial activity. Chlorhexidene gluconate gel showed the largest inhibitory zones. The antimicrobial action of both medicaments decreased significantly with time, with calcium hydroxide showing no antimicrobial action after 72 hours. In conclusion, 2% chlorhexidene gel showed better antimicrobial activity than calcium hydroxide, and the effective antimicrobial action of both medicaments decreased after 48 hours.