Genetic damage in human peripheral lymphocytes exposed to antimicrobial endodontic agents

Objective. Formocresol, paramonochlorophenol, or calcium hydroxide have been widely used in dental practice to eradicate bacteria and consequently to produce root canal disinfection. Taking into consideration strong evidence for a relationship between DNA damage and carcinogenesis, the purpose of the present study was to evaluate the genotoxic effects of antimicrobial endodontic compounds in human peripheral lymphocytes by single-cell gel ( comet) assay. This technique detects DNA strand breaks in individual cells.Study design. A total of 10 mu L of the tested substance solution (formocreso1, paramonochlorofeno1, and calcium hydroxide at 100-mu g/mL concentration) was added to human peripheral lymphocytes from 10 volunteers for 1 hour at 37 degrees C. The negative control group was treated with vehicle control (PBS) for 1 hour at 37 degrees C, as well. For the positive control group, lymphocytes were exposed to hydrogen peroxide at 100 mu M during 5 minutes on ice.Results. No DNA breakage was detected after a treatment of peripheral lymphocytes by formocresol, paramonochlorophenol, or calcium hydroxide at 100 mu g/mL.Conclusions. In summary, our results indicate that exposure to formocresol, paramonochlorophenol, or calcium hydroxide may not be a factor that increases the level of DNA lesions in human peripheral lymphocytes as detected by single-cell gel (comet) assay.

Evaluation of the Effects of Endodontic Materials on Fibroblast Viability and Cytokine Production

Introduction: Recently, a new sealer composed of Portland cement named Endo-CPM-Sealer was developed. The aim of this study was to investigate the effects of Endo-CPM-Sealer (EGEO SRL, Buenos Aires, Argentina), Sealapex (Sybron Endo, Glendora, CA), and Angelus MTA (Angelus, Londrina, Brazil) on cell viability and cytokine (interleukin [IL]-1 beta and IL-6) production by mouse fibroblasts. Methods: Millipore culture plate inserts with polyethylene tubes filled with materials were placed into 24-well cell culture plates with mouse fibroblasts. Cells cultured with only empty polyethylene tubes were used as the control. After 24 hours, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was used to evaluate the cell viability. For cytokine assay, mouse fibroblasts were incubated in 24-well flat-bottom plates with set material disks at the bottom. Cells cultured without the material disks served as the negative control. After 24 hours of incubation, culture media were collected for cytokine evaluation by using an enzyme-linked immunosorbent assay. The data were statistically analyzed by analysis of variance and Bonferroni correction. Results: Endo-CPM-Sealer, Sealapex, and Angelus MTA did not inhibit the cell viability. All materials induced IL-6 releasing, but the amount was not statistically significant compared with the control group. Angelus MTA induced IL-1 beta releasing significantly more than the control. Conclusions: All materials were not considered cytotoxic in fibroblast culture. (J Endod 2009;35:1577-1579)

Release of formaldehyde by 4 endodontic sealers

Objective. The purpose of this study was to evaluate the release of formaldehyde by some root canal filling materials. Study design. Two older endodontic sealers, AH 26 and Endomethasone, and 2 recently available sealers, AH Plus and Top Seal, were analyzed. Infrared and electronic spectroscopy were used to determine formaldehyde content after set of the materials. Results. Analysis showed that the AH 26 and Endomethasone sealers released formaldehyde. Although the AH Plus and Top Seal sealers have similar chemical composition, they released formaldehyde in a minimal concentration. Conclusions. The AH 26 and Endomethasone sealers released formaldehyde after setting; however, a minimum release was observed for the AH Plus and Top Seal sealers. Copyright © 1999 by Mosby, Inc.

Evaluation of apical sealing of three endodontic sealers

Aim: The apical sealing ability of three different endodontic sealers was evaluated in extracted teeth using dye penetration. Methodology: The root canals of 99 extracted human maxillary central incisors were prepared sequentially 2 mm beyond the apical foramen with a size 55 Nitiflex file. The teeth were divided into three experimental groups and obturated by lateral condensation of cold gutta-percha and one of the following sealers: group 1, zinc oxide and eugenol sealer (Fill Canal); group 2, glass ionomer sealer (Ketac-Endo) and group 3, epoxy resin sealer (AH Plus). The teeth were covered with nail varnish to within 1 mm of the apical foramen and immersed in 2% methylene blue in a reduced pressure environment for 24h. After this period, the teeth were washed and cut longitudinally for apical leakage analysis. The values were obtained from the maximum depth of leakage as well as the average between the maximum and minimum values observed for each group. Results: Statistical evaluation of the results showed no significant difference in the leakage between Fill Canal and Ketac-Endo (P > 0.05). Leakage with AH Plus was significantly less (P < 0.01) than with the other sealers. Conclusions: All three sealers allowed some leakage to occur. Leakage with AH Plus was significantly different than with Fill Canal or Ketac-Endo.

Mineral trioxide aggregate repair of lateral root perforations

This study was conducted to observe the healing process of intentional lateral root perforation repaired with mineral trioxide aggregate (MTA). Forty-eight root canals of dogs' teeth were instrumented and filled. After partial removal of the filling, an intentional perforation was made with a bur in the lateral area of the root. The perforations were repaired with MTA or Sealapex (control group). Histological analysis occurred 30 and 180 days after treatment. Results showed no inflammation and deposition of cementum over MTA in the majority of the specimens. In the 180-day period, Sealapex exhibited chronic inflammation in all the specimens and slight deposition of cementum over the material in only three cases. In conclusion, MTA exhibited better results than the control group. Copyright © 2001 by The American Association of Endodontists.

Radiographic evaluation of periradicular repair after endodontic treatment of dog's teeth with induced periradicular periodontitis

Eighty-four root canals of premolars from six dogs were left open for 7 days, and then sealed and followed for 45 days until periradicular periodontitis developed. The root canals were then treated endodontically using 5.25% sodium hypochlorite as the irrigating solution. After instrumentation, all root canals were filled with a calcium hydroxide-based antibacterial dressing (Calen PMCC or Calasept) that was left in place for 30 days. After this period the root canals were filled with gutta-percha cones and a root canal sealer (Sealapex or AH Plus)-group I: Calen PMCC + Sealapex; group II: Calasept + Sealapex; group III: Calen PMCC + AH Plus; and group IV: Calasept + AH Plus. Periapical radiographs of the teeth were made after root canal filling and after 90, 180, 270, and 360 days. Radiographic images were digitalized by scanning, and the Mocha program was used to measure the periapical lesions. Analysis showed that the lesions of groups I to III were statistically similar reduction in size, whereas group IV had a smaller reduction in lesion size (p < 0.05). Copyright © 2001 by The American Association of Endodontists.

Apical and periapical repair of dogs' teeth with periapical lesions after endodontic treatment with different root canal sealers.

The aim of this study was to evaluate the apical and periapical repair after root canal treatment of dogs' teeth with pulp necrosis and chronic periapical lesion using different root canal sealers. After periapical lesion induction, forty-four root canals of 3 dogs were submitted to biomechanical preparation using 5.25% sodium hypochlorite as an irrigating solution. A calcium hydroxide dressing (Calen PMCC) was applied for 15 days and the root canals were filled using the lateral condensation technique with gutta-percha points and Sealapex, AH Plus or Sealer Plus for sealing. After 180 days, the animals were sacrificed by anesthetic overdose and the obtained histological sections were stained with hematoxylin-eosin for optical microscopic analysis of the apical and periapical repair. The groups filled with Sealapex and AH Plus had better histological repair (p < 0.05) than the group filled with Sealer Plus, that had unsatisfactory results.

Antimicrobial endodontic compounds do not modulate alkylation-induced genotoxicity and oxidative stress in vitro

Objective: To investigate if formocresol, paramonochlorophenol, or calcium hydroxide modulate the genotoxic effects induced by the oxidatively damaging agent hydrogen peroxide (H 2O 2) or the alkylating agent methyl methanesulfonate (MMS) in vitro by using single cell gel (comet) assay. Study design: Chinese hamster ovary (CHO) cells in culture were exposed directly to formocresol, paramonochlorophenol, or calcium hydroxide (adjusted to 100 μg/mL) for 1 hour at 37°C. Subsequently the cultures were incubated with increasing concentrations (0-10 μmol/L) of MMS in phosphate-buffered solution (PBS) for 15 minutes at 37°C or of H 2O 2 at increasing concentrations (0-100 μmol/L) in distilled water for 5 minutes on ice. The negative control cells were treated with PBS for 1 hour at 37°C. The parameter from the comet assay (tail moment) was assessed by the Kruskal-Wallis nonparametric test followed by a post hoc analysis (Dunn test). Results: Clear concentration-related effects were observed for the genotoxin-exposed CHO cells. Increase of MMS-induced DNA damage was not significantly altered by the presence of the compounds tested. Similarly, no significant changes were observed when hydrogen peroxide was used with the endodontic compounds evaluated. Conclusion: Formocresol, paramonochlorophenol, and calcium hydroxide are not able to modulate alkylation-induced genotoxicity or oxidative DNA damage as depicted by the single cell gel (comet) assay. © 2006 Mosby, Inc. All rights reserved.

In vitro antimicrobial activity of endodontic sealers, MTA-based cements and Portland cement.

The aim of this study was to evaluate the antimicrobial activity of different root-end filling materials - Sealer 26, Sealapex with zinc oxide, zinc oxide and eugenol, white and gray Portland cement, white and gray MTA-Angelus, and gray Pro Root MTA - against six different microorganism strains. The agar diffusion method was used. A base layer was made using Müller-Hinton agar (MH) and wells were formed by removing the agar. The materials were placed in the wells immediately after manipulation. The microorganisms used were: Micrococcus luteus (ATCC9341), Staphylococcus aureus (ATCC6538), Escherichia coli (ATCC10538), Pseudomonas aeruginosa (ATCC27853), Candida albicans (ATCC 10231), and Enterococcus faecalis (ATCC 10541). The plates were kept at room temperature for 2 h for prediffusion and then incubated at 37 degrees C for 24 h. Triphenyltetrazolium chloride 0.05% gel was added for optimization, and the zones of inhibition were measured. Data were subjected to the Kruskal-Wallis and Dunn tests at a 5% significance level. The results showed that all materials had antimicrobial activity against all the tested strains. Analysis of the efficacy of the materials against the microbial strains showed that Sealapex with zinc oxide, zinc oxide and eugenol and Sealer 26 created larger inhibition halos than the MTA-based and Portland cements (P < 0.05). On the basis of the methodology used, it may be concluded that all endodontic sealers, MTA-based and Portland cements evaluated in this study possess antimicrobial activity, particularly the endodontic sealers.

Susceptibility of strict and facultative anaerobes isolated from endodontic infections to metronidazole and β-lactams

Endodontic infections are mixed aerobic-anaerobic infections and several microbial groups associated to these pathologies are also involved in orofacial infections. The goal of this study was to evaluate the susceptibility of microorganisms isolated from endodontic infections to β-lactams and metronidazole and verify the production of β-lactamases. Clinical specimens were collected from 58 endodontic infections of 52 patients. The microorganisms were isolated in selective and non-selective culture media, under anaerobiosis and aerobiosis, and identified using biochemical methods. In the susceptibility tests, it was used an agar dilution method, and Wilkins-Chalgren agar enriched with blood, hemin and menadione for the anaerobes, while Mueller-Hinton agar was employed for the facultative anaerobes. The production of β-lactamases was evaluated through the biological and chromogenic cephalosporin methods. All tested isolates were sensitive to imipenem and 99.3% to amoxicillin/clavulanate association, while 16.1% showed resistance to amoxicillin and penicillin G, and 4.89% to cefoxitin. Resistance to metronidazole was just found in facultative anaerobes. Production of β-lactamases was detected in 18.2% of the isolates and presented a correlation with resistance to β-lactams.

The effect of endodontic materials on the optical density of dyes used in marginal leakage studies

The aim of this study was to determine the effect of the exposure of different endodontic materials to different dye solutions by evaluating the optical density of the dye solutions. Seventy-five plastic tubes were filled with one of the following materials: AH Plus, Sealapex, Portland cement, MTA (Angelus and Pro Root) and fifteen control plastic tubes were not. Each specimen of material and control was immersed in a container with 1 ml of each dye solution. A 0.1 ml-dye solution aliquote was removed before immersion and after 12, 24, 48 and 72 hours of each specimen immersion to record its optical density (OD) in a spectrophotometer. Statistical analysis was performed with ANOVA and Tukey tests (5%). No significant difference was found among any of the solution OD values for AH Plus cement. Portland cement promoted different OD values after 12 hours of immersion. MTA-Angelus cement presented different OD values only for 2% rhodamine B and the MTA-Pro Root cement presented different OD values in all 2% rhodamine B samples. Sealapex cement promoted a reduction in the India Ink OD values. Dye evaluation through OD seems to be an interesting method to select the best dye solution to use in a given marginal leakage study.