Enterococcus faecalis is a bacterial species often found in root canals with failed endodontic treatment. Alkaline pastes are widely used in Endodontics because of their biocompatibility and antimicrobial activity, but this microorganism can resist alkalinity. The purpose of this study was to evaluate in vitro the alkaline pH resistance of E. faecalis for different periods up to 14 days. Samples were obtained from the oral cavity of 150 patients from the Endodontic clinic. The pH of the experimental tubes (n=84) was first adjusted with 6M NaOH to pH values of 9.5, 10.5, 11.5 and 12.5 (21 tubes per pH). Twenty clinical isolates and the ATCC 29212 strain were tested. The 5 positive controls and experimental tubes of each pH were inoculated with 10 µL of bacterial suspension and incubated at 36 °C for 24, 48 and 72 h, 7 and 14 days. For each period, the turbidity of the medium was visually compared with a 0.5 McFarland standard. The presence of the microorganism was confirmed by seeding on M-Enterococcus agar. Four tubes containing BHI broth adjusted to the tested pHs were incubated for 14 days to verify if pH changes occurred. The pH of inoculated BHI broth was also measured on day 14 to determine if the microorganism acidified the medium. The growth of all E. faecalis strains occurred at pH 9.5 to 11.5 in all periods. Although turbidity was not observed at pH 12.5, there was growth of 13 and 2 strains at 24 and 48 h, respectively, on M-Enterococcus agar. No tube showed growth at pH 12.5 after 72 h. It was concluded that E. faecalis can survive in highly alkaline pH, and some clinical isolates require 72 h at pH 12.5 to be killed.

The aim of this study was to evaluate, by confocal laser scanning microscopy (CLSM), the effect of Ca(OH) 2 dressing on the depth of dentinal tubule sealer penetration and the percentage of sealer-dentin adaptation in the coronal, middle, and apical thirds of teeth filled with methacrylate-based resin sealer (Epiphany). Methods: A total of 30 extracted single-rooted human mandibular incisors were instrumented up to file #40.04 (ProFile), with 1.0% NaOCl as irrigating solution. The teeth were randomly divided into three groups (n = 10): GI = no Ca(OH) 2 dressing (control group); GII = Ca(OH) 2 for 14 days + removal with saline solution and #40 K-file; and GIII = similar to Group II plus 17% EDTA for dressing removal. The Epiphany sealer was labeled with Rhodamine B dye, and all canals were filled with the Epiphany system. Three sections of each tooth were sectioned and viewed under 5X and 40X magnifications. Results: ANOVA and Tukey tests showed significantly lower values of sealer penetration depth in the apical third compared to the middle and coronal thirds (p < 0.05). The deepest sealer penetration was observed in the coronal and middle thirds of Group II. Groups II (93%) and III (86%) had the highest percentage of adaptation compared with Group I (78%) (p < 0.05). Conclusions: Ca(OH) 2 favors the depth of methacrylate-based sealer penetration and the percentage of sealer-dentin adaptation in teeth filled with the Epiphany system.

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Aim:This study aimed to describe the morphological and morphometric aspects of fused mandibular second molars with radicular shallow grooves using micro-computed tomography (CT).Materials and Methods:Eighty-eight mandibular second molars with fused roots were scanned in a micro-CT scanner at a voxel size of 19.6 μm. After reconstruction, only molars without C-shaped roots and presenting shallow radicular grooves were selected. 30 molars were chosen for further analysis. Canal cross-sections were classified according to Fan's modified classification (C1, C2, C3, and C4) and morphometric parameters at the apical region, examination of accessory foramina and tridimensional configuration were evaluated.Results:Three-dimensional reconstructions indicated a higher prevalence of merging type (n = 22). According to Fan's modified classification, the C4 configuration was predominant in the 3 apical mm. Roundness median values revealed a more round-shaped canals at 3 mm (0.72) than at 2 (0.63) and 1 (0.61) mm from the apex. High values of major and minor diameters were observed in the canals of these evaluated sections. In addition, few accessory apical foramina were observed at 1 and 2 mm from the apex. The average distance between last accessory foramina and the anatomic apex was 1.17 mm. A less complex internal anatomy is found when a mandibular second molar presents fused roots with shallow radicular grooves. The merging type canal was frequently observed. Moreover, the C4 configuration was predominant at a point 3 mm from the apex and presented rounded canals, large apical diameters, and few accessory foramina. The cervical and middle thirds presented C3 and C1 canal configurations most frequently.Conclusion:A minor morphological complexity is found when fused mandibular second molars present shallow radicular grooves.

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Periodontite apical induzida em cães. Efeito do tratamento endodôntico. Estudo microbiológico, tomográfico e de microscopia confocal.