Comparing post-obturation of apical microleakage following the use of different intracanal chelators

Objectives: different chelators may be used during root canal treatment, offering various advantages including lubricant effect inside the canal and smear layer removal. However, chelator residues in narrow root canals can lead to apical microleakage. The aim of this in-vitro study was to compare apical microleakage following the use of three root canal chelators via fluid filtration method in root canals instrumented with ProTaper rotary system

Methods: sixty-eight distobuccal canals of maxillary first molars were randomly divided into six groups of four experimental [n=15] and a positive and a negative control group [n=4]. In groups one to three, RC-Prep, 17% EDTA and Glyde File Prep were used as chelators, respectively and sodium hypochlorite [NaOCl] was used as irrigant in all groups except for group four. In group four, root canals were instrumented without chelators and only saline was used for irrigation. Root canals in all groups were prepared using ProTaper rotary system up to F[2] file and filled using cold lateral condensation technique with gutta-percha and AH26 sealer. Apical microleakage was assessed by fluid filtration method. The data were subjected to Kruskal-Wallis test

Results: no significant differences were noted among the experimental groups regarding apical microleakage [p>0.05]. However, preparations with RC Prep+ NaOCl and Glyde File Prep+ NaOCl yielded the highest and the lowest values of apical microleakage, respectively

Conclusion: use of different chelators did not cause statistically significant difference in apical microleakage of root canals

Cytoxicity of root canal antiseptics used in dental practice on L929 fibroblasts: calcium hydroxide powder vs. 2% chlorhexidine solution

Chlorhexidine solution is one of the widely used mouth antiseptic liquid that prevents teeth tissue damage and also has application as a root canal antiseptic. In this study, cytotoxicity of 2% chlorhexidine solution is compared with another root canal antiseptic, calcium hydroxide powder. Cell cytotoxicity of both chemicals was assessed on cultured L929 fibroblastic cell line for 1, 12, 24, 48 and 72 hours using MTT assay [Methyl tetrazolium bromide assay]. Untreated L929 cells were used as a negative control group. MTT results were recorded by ELISA reader and analyzed using one-way ANOVA statistical tests. Cytotoxicity of studied chemicals showed significant difference in various dilutions and times [1, 12, 24, 48 and 72 h]. The highest cytotoxic effect of 2% chlorhexidine solution was observed in concentration of 0.016% for 72 h. Treatment of cells with 0.016% of 2% chlorhexidine liquid and calcium hydroxide powder for 72 hours showed 80% and 45% cytotoxicity, respectively. Cytotoxicity of calcium hydroxide is significantly less than 2% chlorhexidine liquid and then application of calcium hydroxide powder as root canal antiseptic is recommended

Comparing microleakage in root canals obturated with nanosilver coated gutta-percha to standard gutta-percha by two different methods

Favorable apical seal of root filling materials is a crucial factor for a successful root canal treatment. The aim of this in vitro study was to compare bacterial and dye microleakage of two root canal filling materials including standard gutta-percha and nanosilver coated gutta-percha, and to evaluate the agreement between results of these two methods. Fifty-eight extracted single-rooted teeth were randomly divided into two experimental groups of 26 each, and two control groups of three each. After decoronation, root canals were instrumented by crown-down technique. Obturation was conducted using standard gutta-percha in one of experimental groups and nanosilver-coated gutta-percha in another group. AH26 sealer was used as the sealer in both experimental groups. Bacterial leakage was investigated after 60 days using Enterococcus [E.] faecalis microbial strains, and dye leakage was assessed during 72 hours using 1% methylene blue. The data were statistically analyzed by Chi-square test, Kaplan-Meier survival analysis, and Cohen's Kappa. There was 84% bacterial leakage in standard gutta-percha group and 76% in nanosilver gutta-percha group. Complete dye leakage occurred in 24% and 27% of standard and nanosilver gutta-percha groups, respectively. The above difference between groups was not significant. In the samples with leakage, recorded times of leakage were not significantly different. There was no significant measure of agreement between dye and bacterial penetration along root-end fillings. There was a poor agreement between dye and bacterial leakage methods. Leakage results produced by nanosilver gutta-percha were comparable to those by standard gutta-percha. Considering the antibacterial effects of nanosilver coated gutta-percha, use of this type of gutta-percha might be more efficacious in endodontic treatments

In vitro evaluation of the antibacterial activity of three root canal sealers

Antibacterial activity is one of the desirable properties of an ideal sealer. This study aimed to compare the antimicrobial effect of three different sealers, i.e. resin [AH26], calcium hydroxide [Apexit] and zinc oxide eugenol [ZOE] based sealers. Direct contact test with agar diffusion was used in this in vitro study. The freshly mixed sealers were AH26, Apexit and pure ZOE. They were prepared according to manufacturer's instruction and placed in prepared wells of 30 agar plates inoculated with Streptococcus [S] mutans and Prevotella [P] melaninogenicus [15 samples for each microorganism]. All plates were incubated for 7 days [196 hour] at 37C under anaerobic conditions, and zones of inhibition were measured after 3 days, 5 days and 7 days. The data were analyzed using Kruskal-Wallis and Friedman tests. In all determined intervals, the antibacterial activity of AH26 was significantly greater than other test materials [P<0.001]. ZOE sealer had moderate effect on test microorganisms, whilst Apexit showed the lowest antibacterial activity on S. Mutans and no antibacterial activity on P. melaninogenicus. The ascending sequence of bacterial growth inhibition zones was as AH26>Pure ZOE>Apexit

Relation between pulpal neuropeptides and dental caries

Dental pulp has neural fibers that produce neuropeptides like Substance P [SP] and calcitonin gene-related peptide [CGRP]. The inflammation of dental pulp can lead to an increase amount of SP and CGRP release, especially in symptomatic irreversible pulpitis. Therefore, it can be assumed that neuropeptides have some role in the progression of inflammation of the dental pulp. The aim of this study was to determine the relation between the presence and concentration of neuropeptides in dental pulps of carious teeth caries. For this purpose, pulpal tissues were collected from 40 teeth [20 carious and 20 intact]. Pulpal samples were cultured for 72 hours. ELISA reader was used for the detection of SP and CGRP in supernatant fluids. Statistical analysis was made by Mann-Whitney U and Chi square tests. SP and CGRP were present in 65% and 20% of inflamed pulpal samples, respectively and 40% and 5% of normal pulpal samples, respectively. Level of SP was significantly higher in inflamed pulp samples compared to intact pulps; however, there was no statistical difference when the other groups and neuropeptides were compared. The mean concentration of SP in normal pulps was 3.4 times greater than that of CGRP; interestingly in inflamed pulps the concentration of SP was 22.3 times greater than CGRP. We can conclude that in inflamed dental pulps, the concentration of SP is higher than CGRP. It can be hypothesized that CGRP has less effect on the inflammatory changes of dental pulps