María Paloma González-Rodríguez

Eradication of Enterococcus faecalis biofilms by cetrimide and chlorhexidine.

INTRODUCTION Enterococcus faecalis is the most commonly isolated bacteria from root canals of teeth with persistent periapical periodontitis. Its ability to grow as a biofilm impedes the elimination of E. faecalis by using irrigating solutions. The purpose of this study was to assess the efficacy of cetrimide and chlorhexidine (CHX), alone and in association, in combined and alternating form, in eradicating biofilms of E. faecalis. METHODS Biofilms grown in the MBEC-high-throughput device for 24 hours were exposed to irrigating solutions for 30 seconds and 1 and 2 minutes. Eradication was defined as 100% kill of biofilm bacteria. The Student t test was used to compare the efficacy of the associations of the 2 irrigants. RESULTS Cetrimide eradicated E. faecalis biofilms at concentrations of 0.5%, 0.0312%, and 0.0078% at 30 seconds and 1 and 2 minutes of contact time, respectively. CHX did not eradicate the biofilms at any of the concentrations (4% initial concentration) or times assayed. The association of 0.1% and 0.05% cetrimide with any concentration of CHX, whether in combined or alternating application, effectively eradicated E. faecalis biofilms at all the contact times tested. Eradication was also achieved with 0.02% and 0.01% cetrimide at 2 minutes. Statistical analysis revealed significantly better results with alternating rather than combined use of cetrimide and CHX (P < .05). CONCLUSIONS The associated use of cetrimide and CHX provided better results than their applications as single agents against E. faecalis biofilms, and the alternating application was significantly more effective than the combined mode of application.

Effectiveness of the EndoActivator System in Removing the Smear Layer after Root Canal Instrumentation

INTRODUCTION Elimination of the smear layer after root canal instrumentation requires the use of irrigating solutions. This cleaning can be completed with passive ultrasonic or sonic irrigation. The aim of this study was to evaluate the effectiveness of the EndoActivator System in removing the smear layer after rotary root canal instrumentation, with and without a final flush of 17% ethylenediaminetetraacetic acid (EDTA) solution, in coronal, middle, and apical thirds. METHODS Forty single-canal teeth were decoronated and randomly divided into 4 groups (n = 10). The groups were instrumented by using Mtwo System. EndoActivator was used with a final rinse of 1 mL of 17% EDTA or 4% NaOCl for 1 minute. The roots were longitudinally split and were grooved in the coronal, middle, and apical thirds. Scanning electron microscopy digital photomicrographs at 400x were taken to evaluate the amount of smear layer in each third. RESULTS The NaOCl/EndoActivator group did not remove any smear layer of the root canal wall (100% in the coronal, middle, and apical thirds). In the groups that used 17% EDTA (with or without EndoActivator), the smear layer was eliminated completely (100%) in the coronal third, but the amount of removal was less in the other two thirds. The comparisons between NaOCl versus NaOCl/EndoActivator groups and EDTA/NaOCl versus EDTA/EndoActivator/NaOCl groups showed no significant differences in root canal thirds. CONCLUSIONS The EndoActivator System did not enhance the removal of smear layer as compared with conventional Max-I-Probe irrigation with NaOCl and EDTA.

Residual and Antimicrobial Activity of Final Irrigation Protocols on Enterococcus Faecalis Biofilm in Dentin

INTRODUCTION The use of root canal irrigating solutions exerting antimicrobial activity and prolonged residual activity is desirable in order to control dentin infection and delay reinfection of the root canal. The aim of this study was to evaluate the residual antimicrobial activity and the capacity to eradicate Enterococcus faecalis biofilm of different irrigating solutions, alone and in combination, in a dentin-volumetric test. METHODS Solutions of 2.5% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), 0.2% cetrimide (CTR), 17% ethylendiaminetetraacetic (EDTA), 7% maleic acid (MA), and regimens of 2.5% NaOCl followed by 17% EDTA or 7% MA and 0.2% CTR or 2% CHX were used to determine their residual activity by exposing treated dentin blocks to E. faecalis for 24 hours. Antimicrobial activity was assayed on 3-week biofilm formed on dentin blocks. Results of residual activity and antimicrobial activity were respectively expressed as the inhibition percentage of biofilm formation and the kill percentage of biofilm. RESULTS A 2% CHX and 0.2% CTR solution showed 100% biofilm inhibition; 2.5% NaOCl showed the lowest residual activity (18.10%). The kill percentage of 2.5% NaOCl and 0.2% CTR was 100% followed by 7% MA and 2% CHX, whereas 17% EDTA was the least effective (44%). Solutions of 7% MA or 17% EDTA followed by 0.2% CTR or 2% CHX showed 100% residual and antimicrobial activity. CONCLUSIONS A 0.2% CTR solution alone and the combinations in which 2% CHX or 0.2% CTR was the final irrigating solution achieved the maximum residual and antimicrobial activity.

Decalcifying effect of 15% EDTA, 15% citric acid, 5% phosphoric acid and 2.5% sodium hypochlorite on root canal dentine

AIM To evaluate and compare ex vivo the decalcifying effect of 15% EDTA, 15% citric acid, 5% phosphoric acid and 2.5% sodium hypochlorite on root canal dentine. METHODOLOGY Two 2-mm-thick slices were cut from the coronal third of the root of 10 human incisors. Each slice was sectioned into two equal parts. Specimens were assigned to one of four groups (n = 10) for immersion in 20 mL of either 15% EDTA, or 15% citric acid, 5% phosphoric acid or 2.5% NaOCl, for three time periods (5, 10 and 15 min). The concentration of Ca(2+) extracted from the dentine was measured by atomic absorption spectrophometry. The amount of calcium extracted was analysed using the Kruskal-Wallis test for global comparisons and the Mann-Whitney U-test for pairwise comparisons. RESULTS In the three time periods, 15% EDTA and 15% citric acid extracted the largest amount of calcium, with no significant differences between them. The 2.5% NaOCl solution extracted insignificant amounts of calcium, whereas 15% EDTA extracted 86.72% of the calcium in the first 5 min, and 15% citric acid and 5% phosphoric acid had a similar pattern of calcium removal (77.03% and 67.08% in first 5 min, respectively). CONCLUSIONS Solutions of 15% EDTA, 15% citric acid and 5% phosphoric acid decalcify root dentine, with most calcium extracted during the first 5 min of action. The efficacy of 15% citric acid and 15% EDTA solutions was significantly greater than that of 5% phosphoric acid solution at each time period (5, 10 and 15 min).

Topographical evaluation of the major apical foramen in permanent human teeth

AIM To determine the distance from the anatomical root apex to the major apical foramen and the position of the major foramen on the root apex. METHODOLOGY Crowns of 926 human teeth were sectioned at the cementum-enamel junction. Specimens were mounted on microscope slides for measurement parallel to the long axis of the teeth. The major foramen was identified as the largest-diameter opening at the root apex. A total of 1331 root specimens were evaluated using an optical stereomicroscope to an accuracy of 0.01 mm at 40 x (+/-10) magnification. The distance from the anatomical apex to the most apical point of the major foramen was measured, and its location (central, buccal, lingual, mesial and distal) was recorded. RESULTS The mean distance between the major foramen and the anatomical root apex was 0.69 mm; the mean distance was larger in posterior teeth (0.82 mm) and smaller in anterior teeth (0.39 mm). A wide range of anatomical apex to major foramen distances were observed in all tooth groups: the greatest distance was in maxillary molars (0.95 mm) followed by mandibular pre-molars (0.87 mm) and mandibular molars (0.80 mm). The major foramen was at the tip of the root in 40% of teeth. The most frequent deviations of the foramen were to the buccal (20%) and distal (14%). CONCLUSION In this sample of teeth without apical resorption the distance between the major foramen and the anatomical root apex was always <1 mm. Deviation of the major foramen from the anatomic apex varied widely amongst tooth groups.

Residual Effectiveness of Final Irrigation Regimens on Enteroccus faecalis-infected Root Canals

INTRODUCTION The application of a final irrigating solution that remains active over a fairly long period of time stands as one strategy for preventing bacterial recolonization or eliminating the bacteria that persist after root canal treatment. The aim of this study was to evaluate the residual antimicrobial activity of four final irrigation regimens in root canals contaminated with Enterococcus faecalis. METHODS Biofilms of E. faecalis were grown in uniradicular roots for 4 weeks. After preparing the roots chemomechanically, four final irrigation regimens were applied: (1) group EDTA-NaOCl, 17% EDTA followed by 5.25% sodium hypochlorite (NaOCl); (2) group MA-NaOCl, 7% maleic acid (MA) followed by 5.25% NaOCl; (3) group EDTA-CHX + CTR, 17% EDTA followed by 2% chlorhexidine (CHX) + 0.2% cetrimide (CTR); and (4) group MA-CHX + CTR, 7% MA followed by 2% CHX + 0.2% CTR. Samples were collected for 60 days to denote the presence of bacterial growth. The Fisher exact test was used to compare the percentages of specimens without E. faecalis regrowth. RESULTS All root canals in which the final irrigant was 5.25% NaOCl yielded positive cultures on the fifth day. Groups EDTA-CHX + CTR and MA-CHX + CTR with a final irrigation of 2% CHX + 0.2% CTR showed respective percentages of samples without regrowth of 72.1% and 66.8% at 60 days. There were no statistically significant differences between these groups. CONCLUSIONS The combination of 2% CHX + 0.2% CTR would be an effective alternative final irrigation regimen given its antimicrobial action over time.

Effectiveness of a Manual Glide Path on the Preparation of Curved Root Canals by Using Mtwo Rotary Instruments

INTRODUCTION Nickel-titanium rotary instruments reduce procedural errors and the time required to finish root canal preparation. The goal of this study was to evaluate the effectiveness of a manual glide path on the preparation of curved root canals with Mtwo rotary system. METHODS Forty buccal root canals with angles of curvature between 25 to 76 degrees were randomly divided into 4 groups (n = 10); 2 groups were instrumented with Mtwo instruments to the full length, and in the other 2 groups a glide path with #08-15 K files was performed before instrumentation with Mtwo system. Digital double radiographic technique was used to determine apical transportation and the change in angle of curvature. Also working time was calculated. RESULTS No statistically significant differences in the angle of canal curvature, apical transportation, and the working time were found between groups with glide path and no glide path. No significant differences were found when comparing the results of 3 variables between degrees of curvature. CONCLUSION The use of a manual glide path before Mtwo rotary system did not influence the apical transportation in curved root canals.

Dissolving efficacy of eucalyptus and orange oil, xylol and chloroform solvents on different root canal sealers

AIM To evaluate the solubility of five root canal sealers in orange oil, eucalyptol, xylol and chloroform solvents. METHODOLOGY The solubility of RoekoSeal, Sealer 26, Epiphany, Endomethasone and EZ-Fill sealers was assessed in orange oil, eucalyptol, xylol, chloroform and distilled water. Seventy-five samples of root canal sealers were prepared and then divided into five groups for immersion in solvent for 2, 5 or 10 min. The means of loss weight were determined for each material in each solvent at all immersion periods, and the values were compared by factorial analysis of variance (anova) and SNK multiple comparisons. RESULTS In the orange and eucalyptus oil groups, there was no significant difference among RoekoSeal, Sealer26, Epiphany and EZ-Fill at the three immersion periods (P > 0.05). With xylol, no significant differences were found at 5 and 10 min (P > 0.05) for each root sealer. Orange and eucalyptus oil solvents were as effective as chloroform at 2 min in dissolving all the root sealers. CONCLUSIONS Xylol was the most effective solvent followed by the chloroform and the essential oils (eucalyptol and orange oil). Orange oil behaved in a similar way to eucalyptus oil.

Eradication of enterococci biofilms by lactic acid aloneand combined with chlorhexidine and cetrimide

Objective: The antimicrobial activity of lactic acid (LA) alone or in combination with chlorhexidine (CHX) and cetrimide (CTR) against three Enterococcus faecalis strains, E. faecalis ATCC 29212, E. faecalis EF-D1 and E. faecalis U-1765, one Enterococcus durans strain and one dual-species biofilm was investigated. Study Design: The irrigating solutions tested were 20%, 15%, 10%, 5% and 2.5% LA, alone and in combination with 2% CHX and with 0.2% CTR. The biofilms were grown in the MBECTM high-throughput device for 24 hours and exposed to the solutions for 30 seconds and 1 minute. “Eradication” was defined as 100% bacterial kill. Results: Twenty percent LA eradicated all enterococci biofilms after 30 seconds contact time. The association of LA + 0.2% CTR achieved better results than LA alone, in contrast with the results obtained using LA + 2% CHX. E. durans was eradicated by all the tested solutions at 1 minute. The dual-species biofilm, E. faecalis ATCC 29212 + E. durans, gave intermediate values of the pure cultures. Conclusions: LA is capable of eradicating enterococci biofilm at a concentration of 20%. The combination of lower concentrations with 0.2% CTR achieved eradication after 1 minute. Key words:Biofilm, cetrimide, chlorhexidine, enterococcus durans, enterococcus faecalis.

Ex vivo microbial leakage after using different final irrigation regimens with chlorhexidine

Objective: To assess the influence of final irrigation protocols with chlorhexidine in the coronal leakage of Enterococcus faecalis in filled root canals. Material and Methods: Seventy single-root canals from extracted teeth were prepared using ProTaper instruments. The irrigation protocol accomplished an alternating irrigation with 5 mL of 2.5% sodium hypochlorite (NaOCl) and 17% EDTA between each file. The teeth were randomly divided into four experimental groups (n=15) according to the final irrigation regimen: group 1, without final irrigation; group 2, irrigation with 10 mL 2.0% chlorhexidine (CHX); group 3, with a final application of EC40TM; and group 4, irrigation with the combination (1:1) of 0.2% CHX + 0.1% cetrimide (CTR). All the teeth were mounted in a two-chamber apparatus and the coronal access was exposed to E. faecalis. The presence of turbidity in the BHI broth over a period of 180 days was observed. The Friedman test was used for statistical analysis. Results: EC40TM varnish showed the least leakage at 180 days, and was statistically similar to 2% CHX. No significant differences were observed between the group without final irrigation and the 2% CHX group or 0.2% CHX + 0.1% CTR. Conclusions: In this ex vivo study, EC40TM showed the longest delayed coronal leakage of E. faecalis, although without significant differences from 2% CHX.