Single session of Nd:YAG laser intracanal irradiation neutralizes endotoxin in dental root dentin.

Endotoxins released in the dental root by Gram-negative microorganisms can be neutralized by calcium hydroxide, when this medication is applied inside the root canal for at least seven days. However, several clinical situations demand faster root canal decontamination. Thus, for faster endotoxin neutralization, endodontists are seeking additional treatments. The in vitro study tested whether or not intracanal Nd:YAG laser irradiation would be able to neutralize endotoxin within the human dental root canal in a single session. Twenty-four human teeth with one root were mounted between two chambers. After conventional endodontic treatment, root canals were contaminated with Escherichia coli endotoxin. Then they were irradiated or not (controls) in contact mode with an Nd:YAG laser (1.5 W, 15 Hz, 100 mJ and pulse fluency of 124 J/cm2). The endotoxin activity was measured using the limulus lysate technique and data were statistically compared (p≤0.05). The concentration of active endotoxin measured in the negative control group was significantly lower than that of the positive control group (p=0.04). The concentrations of endotoxin in both irradiated groups were significantly lower than that of the positive control group (p=0.027) and similar to that of negative control group (p=0.20). A single session of intracanal Nd:YAG laser irradiation is able to neutralize endotoxin in the dental root tissues.

Qualitative SEM/EDS analysis of microleakage and apical gap formation of adhesive root-filling materials.

OBJECTIVE: The aim of this study was to compare the correspondence between gap formation and apical microleakage in root canals filled with epoxy resin-based (AH Plus) combined or not with resinous primer or with a dimethacrylate-based root canal sealer (Epiphany). MATERIAL AND METHODS: Thirty-nine lower single-rooted human premolars were filled by the lateral condensation technique (LC) and immersed in a 50-wt% aqueous silver nitrate solution at 37ºC (24 h). After longitudinal sectioning, epoxy resin replicas were made from the tooth specimens. Both the replicas and the specimens were prepared for scanning electron microscopy (SEM). The gaps were observed in the replicas. Apical microleakage was detected in the specimens by SEM/energy dispersive spectroscopy (SEM/EDS). The data were analyzed statistically using an Ordinal Logistic Regression model and Analysis of Correspondence (α=0.05). RESULTS: Epiphany presented more regions containing gaps between dentin and sealer (p<0.05). There was correspondence between the presence of gaps and microleakage (p<0.05). Microleakage was similar among the root-filling materials (p>0.05). CONCLUSIONS: The resinous primer did not improve the sealing ability of AH Plus sealer and the presence of gaps had an effect on apical microleakage for all materials.

Qualitative SEM/EDS analysis of microleakage and apical gap formation of adhesive root-filling materials

OBJECTIVE: The aim of this study was to compare the correspondence between gap formation and apical microleakage in root canals filled with epoxy resin-based (AH Plus) combined or not with resinous primer or with a dimethacrylate-based root canal sealer (Epiphany). MATERIAL AND METHODS: Thirty-nine lower single-rooted human premolars were filled by the lateral condensation technique (LC) and immersed in a 50-wt% aqueous silver nitrate solution at 37ºC (24 h). After longitudinal sectioning, epoxy resin replicas were made from the tooth specimens. Both the replicas and the specimens were prepared for scanning electron microscopy (SEM). The gaps were observed in the replicas. Apical microleakage was detected in the specimens by SEM/energy dispersive spectroscopy (SEM/EDS). The data were analyzed statistically using an Ordinal Logistic Regression model and Analysis of Correspondence (α=0.05). RESULTS: Epiphany presented more regions containing gaps between dentin and sealer (p<0.05). There was correspondence between the presence of gaps and microleakage (p<0.05). Microleakage was similar among the root-filling materials (p>0.05). CONCLUSIONS: The resinous primer did not improve the sealing ability of AH Plus sealer and the presence of gaps had an effect on apical microleakage for all materials.

Microbiologic endodontic status of young traumatized tooth.

Traumatic dental injuries could expose the dentin and, even the pulp, to the oral environment, making possible their contamination. The presence of microorganisms causes pulpal disease and further a tecidual clutter in the periradicular region. The therapy of periradicular pathosis is the consequence of a correct diagnoses which depends on the knowledge of the nature and complexity of endodontic infections. As there is no information on the microbiology of primary endodontic infection in young teeth, the aim of the current study was to investigate the microbiologic status of root canals from permanent young teeth with primary endodontic infection. Twelve patients with the need for endodontic treatment participated in the study. The selected teeth were uniradicular and had an incomplete root formation. They had untreated necrotic pulp. After the access preparation, nineteen microbiologic samples were obtained from the root canals with sterile paper points. Afterwards, the paper points were pooled in a sterile tube containing 2 ml of prereduced transport fluid. The samples were diluted and spread onto plates with selective medium for Enterococcus spp. and for yeast species and onto plates with non-selective medium. A quantitative analysis was performed. The mean number of cultivable bacterial cells in the root canals was 5.7 × 10(6). In four samples (21.05%) black pigmented species were recovered and the mean number of cells was 6.5 × 10(5). One specimen (5.25%) showed the growth of Enterococcus species and the mean number of cells in this case was of 1.5 × 10(4) . The results showed a root canal microbiota with similar design as seen in completely formed teeth.

In vitro analysis of the penetration of methylene blue dye in human radicular dentin using different methods of impregnation.

The purpose of the present study was to verity whether different conditions of contact with a dye solution would result in different levels of the impregnation by the marker agent in human radicular dentin. The root canals of 60 upper human canines were immersed in methylene blue dye (0.5%, pH 7.0) for 24 h under six different conditions: passive immersion; pre-agitation for 10 min using an endodontic ultrasound; pre-agitation for 10 min using a cleaning ultrasound; 25-mmHg vacuum for 10 min followed by passive immersion; 30-mmHg and 650-mmHg vacuum for 24 h. The roots were longitudinally sectioned and dye impregnation was assessed by a trained and calibrated examiner, using the Q 550 IW image analyser (Leica Qwin, Cambridge, England). The measurements were analysed with anova and Tukey test. The results revealed no significant difference among the different methods for dye impregnation. In the cervical third, impregnation with 30 mmHg was significantly more effective than with endodontic ultrasound or 25 mmHg. At the apical third, no differences were observed between any of the dye impregnation methods. The comparison of different thirds revealed a statistically significant difference between the cervical and apical and the middle and apical thirds, but not between the cervical and middle thirds.