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.

Antimicrobial activity of endodontic sealers based on calcium hydroxide and MTA.

The aim of this study was to evaluate the antimicrobial activity of a new root canal sealer containing calcium hydroxide (Acroseal) and the root canal sealer based on MTA (Endo CPM Sealer), in comparison with traditional sealers (Sealapex, Sealer 26 and Intrafill) and white MTA-Angelus, against five different microorganism strains. The materials and their components were evaluated after manipulation, employing the agar diffusion method. A base layer was made using Müller-Hinton agar (MH) and wells were made by removing agar. The materials were placed into the wells immediately after manipulation. The microorganisms used were: Micrococcus luteus (ATCC9341), Staphylococcus aureus (ATCC6538), 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. The results showed that Sealapex and its base paste, Sealer 26 and its powder, Endo CPM Sealer and its powder, white MTA and its powder all presented antimicrobial activity against all strains. Intrafill and its liquid presented antimicrobial activity against all strains except P. aeruginosa and Acroseal was effective only against M. luteus and S. aureus.

Calcium hydroxide intracanal dressing removal with different rotary instruments and irrigating solutions: A scanning electron microscopy study

This study evaluated the efficacy of 2 types of rotary instruments employed in association with sodium hypochlorite (NaOCl) or EDTA in removing calcium hydroxide (CH) residues from root canals dentin walls. Forty-two mandibular human incisors were instrumented with the ProTaper System up to F2 instrument, irrigated with 2.5% NaOCl followed by 17% EDTA and filled with a CH intracanal dressing. After 7 days, the CH dressing was removed using 4 techniques: NiTi rotary instrument size 25, 0.06 taper (K3 Endo) and irrigation with 17% EDTA (Group 1), NiTi rotary F1 instrument (ProTaper) and irrigation with 17% EDTA (Group 2), NiTi rotary instrument size 25, 0.06 taper and irrigation with 2.5% NaOCl (Group 3) and NiTi rotary F1 instrument and irrigation with 2.5% NaOCl (Group 4). Two roots without intracanal dressing were used as negative controls. Teeth were evaluated by scanning electron microscopy, in the cervical and apical canal thirds. None of the techniques removed the CH dressing completely. In the apical and cervical thirds, F1 instrument was better than instrument size 25, 0.06 taper in removing CH residues (p<0.05), regardless of the final irrigating solution. No difference was found between the irrigating solutions in the groups of F1 instrument and of instrument size 25, 0.06 taper (p>0.05). The negative controls had no CH residues on the dentin walls. In conclusion, the ProTaper F1 instrument was better than K3 Endo instrument size 25, 0.06 taper in the removal of CH intracanal medication, regardless of irrigating solution used.

Dimensional alterations and solubility of new endodontic sealers

This study evaluated the dimensional alterations and the solubility of two experimental endodontic sealers based on Copaifera multijuga oil-resin (Biosealer) and castor oil bean cement (Poliquil), maintained in different storage solutions. Twenty specimens (3 mm diameter and 2 mm height) of each sealer were assigned to 2 groups (n=10) according to the storage solution: simulated tissue fluid (STF) or distilled water (DW). The specimens were stored in these solutions during 90 days, being removed every 30 days for weighting. The solutions were renewed every 15 days. The results were subjected to statistical analysis by Dunn's and Mann-Whitney tests (α=0.05). The solubility of Poliquil was higher in STF (38.4 ± 36.0) than in DW (28.4 ± 15.0), while Biosealer showed higher solubility in DW (34.61 ± 6.0) than in STF (18.59 ± 8.0). The storage solution influenced the behavior of sealers in relation to the weight variation (p=0.0001). Poliquil presented higher variation of weight independent of the solution (p=0.239). Biosealer also presented higher variation of weight regardless of the solution (p=0.0001). The solubility of Biosealer was different from that of Poliquil, but both sealers showed low solubility in STF. Under the tested conditions, neither of the materials were according to the ADA'S specification.

Influence of cutting instruments and adhesive systems on hybrid layer formation.

Influence of cutting instruments and The aim of this study was to analyze the hybrid layer in noncarious dentin prepared by different cutting instruments and restored with composite resin. The cavities were randomly prepared in 40 specimens using a high-speed diamond bur (KG Sorensen 1013) and an ultrasonic tip (CVDentus C22). The cavities were restored with composite resin by varying the adhesive system between the Adper™ Single Bond (2 x 1 system, primer+adhesive) and the Prompt L-Pop™ (3 x 1 system, self-etching). The restorations were hemisected longitudinally and analyzed in the SEM (Scanning electron microscopy) in order to evaluate the hybrid layer and resinous tags characteristics, using scores ranging from 1 to 6. The Pearson test revealed a high correlation coefficient and good significance levels for both intra- and inter-raters values (r=0.90). The data were statistically analyzed using the Mann-Whitney test (P≤0.05). A larger proportion of regular hybrid layers with numerous tags were observed in the dentin prepared using the high-speed diamond burs and restored with a 2 × 1 adhesive system. Alternatively, the 3 × 1 adhesive system promoted the generation of a thin hybrid layer with few tags. After preparation using an ultrasonic tip revealed few or no tags after the preparation and 2 × 1 or 3 × 1 adhesive system application. The high-speed diamond burs produced a dentin surface that was more favorable to restorative material adhesion than the ultrasonic tips, regardless of the adhesive system used.

Antimicrobial effects of ozonated water on the sanitization of dental instruments contaminated with E. coli, S. aureus, C. albicans, or the spores of B. atrophaeus

Objectives: Ozone has been used as an alternative method for the decontamination of water, food, equipment and instruments. The objective of this study was to evaluate the antimicrobial effects of ozonated water on the sanitization of dental instruments that were contaminated by Escherichia coli, Staphylococcus aureus, Candida albicans and the spores of Bacillus atrophaeus. Methods: A total of one hundred and twenty standardized samples of diamond dental burs were experimentally contaminated with E. coli (ATCC 25922), S. aureus (ATCC 6538) and C. albicans (ATCC 18804) and the spores of B. atrophaeus (ATCC 6633) for 30min. After the contamination, the samples were exposed to ozonated water (10mg/L O3) for 10 or 30min. The control group was composed of samples that were exposed to distilled water for 30min. After the exposure to the ozonated water, 0.1mL aliquots were seeded onto BHI agar to count the colony-forming units per milliliter (CFU/mL) of E. coli, S. aureus, and B. atrophaeus. Sabouraud dextrose agar was used to count the CFU/mL of C. albicans. The results were subjected to an analysis of variance and the Tukey test. Results: For all of the microorganisms studied, the ozonated water reduced the number of CFU/mL after 10 and 30. min of sanitization, and this microbial reduction was dependent on the duration of the exposure to the ozonated water. E. coli exhibited the greatest reduction in CFU/mL (2.72-3.78. log) followed by S. aureus (2.14-3.19. log), C. albicans (1.44-2.14. log) and the spores of B. atrophaeus (1.01-1.98. log). Conclusion: The ozonated water was effective in reducing the CFU of E. coli, S. aureus, C. albicans and B. atrophaeus spores, suggesting that ozonated water can be used for the sanitization of dental instruments. © 2012 King Saud Bin Abdulaziz University for Health Sciences.

Antibiofilm activity, pH and solubility of endodontic sealers

Aim: To evaluate antibiofilm activity against Enterococcus faecalis, pH and solubility of AH Plus, Sealer 26, Epiphany SE, Sealapex, Activ GP, MTA Fillapex (MTA-F) and an experimental MTA-based Sealer (MTA-S). Methodology: Sealer samples were manipulated and stored for 2 or 7 days. Prepared sealers were evaluated by a modified direct contact test (DCT) for 5 h, 10 h or 15 h with biofilm previously induced on bovine dentine for 14 days. In the control group, the biofilm was not exposed to the sealers. The number of colony-forming units (CFU mL-1) in the remaining biofilm was determined. Sealer solubility was assessed by the percentage of mass loss after 15 h of immersion in distilled water. Sealer pH was measured at 5 h, 10 h and 15 h. Statistical analysis was performed using Kruskal-Wallis and Dunn or anova and Tamhane's T2 tests, at 5% significance. Results: At 2 days post-manipulation, the DCT showed that Sealapex and MTA-F were associated with a reduction in the number of bacteria in all 3 contact periods evaluated, compared with the control group (P < 0.05). At 7 days, Sealapex had the greatest antibiofilm action at 10 h and 15 h. Sealapex had the highest pH values 2 and 7 days post-manipulation. Regarding the solubility, at 2 days the highest values were observed for MTA-F, MTA-S, Sealapex and Activ GP (P < 0.05). At 7 days, MTA-S and MTA-F had greater solubility than the other materials (P < 0.05). AH Plus had the lowest solubility for both post-manipulation periods (P < 0.05). Conclusion: Sealapex and MTA-F were associated with a reduction in the number of bacteria in biofilms and had greater solubility. The high solubility and pH may be related to the antibacterial activity of these materials. © 2012 International Endodontic Journal.

Physicochemical and mechanical properties of zirconium oxide and niobium oxide modified Portland cement-based experimental endodontic sealers

Aim: To evaluate the physicochemical and mechanical properties of Portland cement-based experimental sealers (ES) with different radiopacifying agents (zirconium oxide and niobium oxide micro- and nanoparticles) in comparison with the following conventional sealers: AH Plus, MTA Fillapex and Sealapex. Methodology: The materials were tested for setting time, compressive strength, flow, film thickness, radiopacity, solubility, dimensional stability and formaldehyde release. Data were subjected to anova and Tukey tests (P < 0.05). Results: MTA Fillapex had the shortest setting time and lowest compressive strength values (P < 0.05) compared with the other materials. The ES had flow values similar to the conventional materials, but higher film thickness (P < 0.05) and lower radiopacity (P < 0.05). Similarly to AH Plus, the ES were associated with dimensional expansion (P > 0.05) and lower solubility when compared with MTA Fillapex and Sealapex (P < 0.05). None of the endodontic sealers evaluated released formaldehyde after mixing. Conclusion: With the exception of radiopacity, the Portland cement-based experimental endodontic sealers presented physicochemical properties according to the specifications no 57 ANSI/ADA (ADA Professional Product Review, 2008) and ISO 6876 (Dentistry - Root Canal Sealing Materials, 2012, British Standards Institution, London, UK). The sealers had setting times and flow ability that was adequate for clinical use, satisfactory compressive strength and low solubility. Additional studies should be carried out with the purpose of decreasing the film thickness and to determine the ideal ratio of radiopacifying agents in Portland cement-based root canal sealers. © 2013 International Endodontic Journal.

Use of cone-beam tomography and digital subtraction radiography for diagnosis and evaluation of traumatized teeth treated with endodontic surgery and MTA. A case report

The aim of this paper was to report the diagnosis and evaluation of periradicular bone repair by using computed tomography and digital subtraction radiography in an endodontic surgery case treated with mineral trioxide aggregate (MTA). The patient had local swelling and fistula 7years after trauma in the upper jaw. Periapical lesion on tooth #12 and root resorption of tooth #11 were detected radiographically. Endodontic therapy and placement of intracanal medication were carried out. After 3months, with no improvement in the clinical signs and symptoms, computed tomography was performed, showing extensive apical bone resorption on tooth #12 and dental resorption promoting communication of the root canal with the periodontium of tooth #11. The patient was referred to endodontic surgery. After surgery and postoperative periods of 15, 30, 60, 90, and 120days, standardized radiographs were taken, digitized, and subjected to digital subtraction of the images using Adobe Photoshop CS software. Four years later, a cone-beam computed tomography was performed, showing bone repair and absence of root resorption at tooth #11. In this clinical case, digital subtraction radiography was effective for early detection of new bone formation and evolution of repair. © 2011 John Wiley & Sons A/S.

Avaliação dos sistemas MTwo Retratamento e ProTaper Universal Retratamento na remoção de guta-percha e novos cimentos endodônticos dos canais radiculares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da resistência à fadiga de instrumentos rotatórios do Sistema Pro Taper Universal por meio de ensaio dinâmico

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação microscópica do preparo apical de canais radiculares curvos pela instrumentação manual rotatória e mecanizada rotatória e oscilatória utilizando o sistema Protaper Universal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)