Pilar Baca

Enterococcus faecalis Biofilms Eradication by Root Canal Irrigants

The aim of this study was to evaluate the minimal biofilm eradication concentration (MBEC) of sodium hypochlorite (NaOCl), chlorhexidine (CHX), EDTA, and citric and phosphoric acids after 1, 5, and 10 minutes of exposure to biofilms of Enterococcus faecalis. The biofilms grew in the MBEC high-throughput device for 24 hours at 37 degrees C and were exposed to 10 serial two-fold dilutions of each irrigating solution. The viable cell counts were log(10) transformed, and a concentration of an irrigant was considered to eradicate the biofilms when it produced a reduction of > or = 5 logarithmic units. NaOCl was the most effective agent, capable of eradicating the biofilms after 1 minute at a concentration of 0.00625%. CHX eradicated biofilm after 5 minutes at 2%. EDTA and citric and phosphoric acid solutions were not effective against the biofilms at any concentration or time tested.

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.

Sealant and Fluoride Varnish in Caries: a Randomized Trial:

Little is known about the effect of discontinuation of sealant or fluoride varnish. The purpose of this study was to compare sealant with fluoride varnish in the prevention of occlusal caries in permanent first molars of children over a nine-year period: 4 yrs for program evaluation plus 5 yrs of discontinuation. A clinical trial was conducted on three groups of six- to eight-year-old schoolchildren: a control group (n = 45); a group (n = 37) in which sealant was applied and reapplied up to 36 mos; and a group (n = 38) in which fluoride varnish was applied and re-applied up to 42 mos. Percent caries reduction was studied in these initially healthy molars with complete occlusal eruption: 129 (control), 113 (sealant), and 129 (varnish) molars met inclusion criteria. Of these, 76.7%, 26.6%, and 55.8% had developed occlusal caries at 9 yrs, which implies caries reductions of 65.4% (SE = 8.5%) for sealants vs. control and 27.3% (SE = 10.2%) for varnish vs. control. Furthermore, the varnish program was not effective during the discontinuation period.

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.

The Influence of dft Index on Sealant Success: A 48-month Survival Analysis

Early loss of pit and fissure sealants is considered to be primarily dependent on inadequate isolation of the tooth from salivary contamination during application. Gradual additional loss is considered to be caused by occlusal wear, shearing forces, and marginal failure. Our hypothesis is that the caries risk of the child may be an additional factor in sealant loss. The objective of this study was to analyze the influence of caries history in primary teeth (dft index) on the success of sealants. Delton light-polymerized sealant was applied in 104 six- to eight-year-old children, followed for four years on a six-month-visit basis. All sound permanent first molars were sealed during the study. A survival analysis was used to describe sealant success over time. A Cox proportional hazards regression model was built to test the influence on sealant success of the dft index and site of sealant application (mandibular occlusal surface, maxillary fossae, and maxillary disto-lingual fissure), controlling for some potential confounders. Sealant half-life was 46 months. Site and dft index were related to sealant survival. The maxillary fossae showed the best retention, followed by the mandibular occlusal site and the maxillary disto-lingual fissure. The higher the dft, the higher the risk of sealant failure. This study has implications for sealant study designs and public sealant programs.

Effect of chlorhexidine-thymol varnish on root caries in a geriatric population: A randomized double-blind clinical trial

OBJECTIVES Little is known about the effect of Cervitec, a chlorhexidine-thymol varnish, on root caries. Our objective was to determine whether a 3-monthly application of Cervitec over 1 year would limit the progress of existing root caries lesions and reduce the incidence of dental root caries in a group of dentate institutionalized elderly, as a complement to their usual oral hygiene practices. METHODS A double-blind randomized clinical trial was conducted in 68 subjects (34 per group) in two residences in Almería (Spain). Twenty-one subjects with 60 root caries lesions and 25 with 65 lesions, in the Cervitec and placebo groups, respectively, completed the study. Varnishes were applied twice in the first week, 1 month later, and every 3 months until the end of the study. Clinical parameters associated with established lesions were determined at baseline and after 6 and 12 months, as was the incidence of root caries lesions. RESULTS The clinical evolution of lesions was significantly better in the Cervitec group as opposed to the placebo group in terms of width, height, color, and texture. The increase in root caries was significantly lower (p=0.039) in the Cervitec group. CONCLUSION According to these results, Cervitec may help to control established root lesions and reduce the incidence of root caries lesion among institutionalized elderly.

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.

Antimicrobial substantivity over time of chlorhexidine and cetrimide.

INTRODUCTION To reach an adequate control of dentin infection and to promote success in endodontic therapy, antimicrobial irrigating solutions with confirmed substantivity are recommended. The aim of the present study was to evaluate the antimicrobial substantivity against Enterococcus faecalis of a dentin-volumetric unit exposed for 1 minute to chlorhexidine (CHX) and cetrimide (CTR). METHODS Standardized coronal dentin blocks of human molars, with and without collagen, were treated for 1 minute with 0.2% and 2% CHX and 0.2% CTR. Afterwards, they were exposed to E. faecalis suspension to determine the antimicrobial substantivity over a period of 60 days. Results were analyzed by means of Kaplan-Meier survival analysis (P < .05). RESULTS A direct relationship was seen between CHX concentration and survival time, and the most statistically significant results were obtained in specimens with collagen. CTR showed intermediate survival values close to those of 2% CHX. CONCLUSIONS The present study shows that 2% CHX used for 1 minute provides the longest substantivity followed by 0.2% CTR when applied to a dentin-volumetric model.

Antimicrobial Activity of a Sodium Hypochlorite/Etidronic Acid Irrigant Solution

INTRODUCTION The aim of this study was to evaluate the antimicrobial activity of a 2.5% sodium hypochlorite (NaOCl)/9% etidronic acid (HEBP) irrigant solution on Enterococcus faecalis growing in biofilms and a dentinal tubule infection model. METHODS The antimicrobial activity of the solutions 2.5% NaOCl and 9% HEBP alone and associated was evaluated on E. faecalis biofilms grown in the Calgary biofilm model (minimum biofilm eradication concentration high-throughput device). For the dentinal tubule infection test, the percentage of dead cells in E. faecalis-infected dentinal tubules treated with the solutions for 10 minutes was measured using confocal laser scanning microscopy and the live/dead technique. Available chlorine and pH of the solutions were also measured. Distilled water was used as the control. Nonparametric tests were used to determine statistical differences. RESULTS The highest viability was found in the distilled water group and the lowest in the NaOCl-treated dentin (P < .05). Both NaOCl solutions killed 100% of the E. faecalis biofilms and showed the highest antimicrobial activity inside dentinal tubules, without statistical differences between the 2 (P < .05). The HEBP isolated solution killed bacteria inside dentinal tubules but did not present any significant effect against E. faecalis biofilms. The incorporation of HEBP to NaOCl did not cause any loss of available chlorine within 60 minutes. CONCLUSIONS HEBP did not interfere with the ability of NaOCl to kill E. faecalis grown in biofilms and inside dentinal tubules.

Three-dimensional evaluation of root canal morphology in lower second premolars of early and middle pleistocene human populations from atapuerca (Burgos, Spain)

The aim of this study is to describe the morphology of the roots and root canals of permanent lower second premolars (LP4s) with fully developed roots of five hominin groups: Homo sp. (ATE9-1 specimen) from Atapuerca-Sima del Elefante locality, H. antecessor (ATD6-4 and ATD6-125) from Atapuerca-Gran Dolina TD6 locality, H. heidelbergensis from Atapuerca-Sima de los Huesos locality, H. neanderthalensis from Krapina, Regourdou, and Abri Bourgeois-Delaunay localities, and two contemporary H. sapiens groups. The teeth were scanned by means of microtomography. The roots were divided into three virtual segments by three planes: cemento-enamel junction (CEJ), mid-root (MR), and mid-apex (MA). Volumetric and planar direct measurements of the whole teeth and each segment were taken. Descriptive statistical analyses and nonparametric Mann-Whiney test were performed to test for significant differences (P < 0.025) between groups. ATE9-1 and Gran Dolina-TD6 fossils present intricate radicular complexes that might be transitional between the morphologies of Australopithecus robustus and African early Homo and the derived conditions typically found in later Homo. In H. neanderthalensis and H. heidelbergensis, the root canals are wide, with small apical convergence. This trait is particularly pronounced in the Sima de los Huesos sample which may reflect a particularity of this population. Our study demonstrates the potential of hominin roots and root canals as untapped sources of taxonomic information when the tooth crown is fragmented. Future studies, including more fossil specimens and species will shed light in the polarity of the morphologies observed.