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Background Endodontic ledge (EL) formation is the most common complication of endodontic treatment. Although various etiological factors have been identified, canal curvature is the most significant variable correlated with EL formation. The aim of this micro-computed tomographic (micro-CT) study was to evaluate EL position in the mesial canals of the lower molars in relation to the degree of canal curvature. Methods Forty intact mandibular first molars with independent mesial canals with 20°–40° primary mesio-distal curvature, 10°–30° buccal-lingual canal curvature and 4 P Results The α angles appeared inversely proportional to canal curvatures in the buccal-lingual and mesio-distal projections. The mean α angle was 36.4° (standard deviation 10.64; 95% confidence interval 34.1–40.9). Conclusion Within the limitations of this study, endodontic ledges develop in the opposite direction to the three-dimensional canal curvature and their position is influenced by the degree of curvature. Clinically, the α angle values may be related to the recommended direction to manage endodontic ledges.

Many dental components (lower incisors, mesial roots of the lower molars, upper bicuspids, the mesiobuccal root of the upper bicuspids, the mesiobuccal root of the upper first molars) have two root canals at cavity level to which two main canals correspond. These two canals either have two separate apical foramina or they merge in the apical third and have a single apical foramen. The endodontist's failure to recognize the latter anatomical characteristic results in deformation of the shared portion of the root canal and laceration of the apical foramen. This in turn leads to disappearance of the tapering cone shape, which acts as a "stop" for the filling material during condensation.

To evaluate the influence of operator experience on adhesive technique and to assess the clinical performances of two different adhesive systems.90 cervical lesions in 42 subjects, with a mean age of 52.4 years (range between 32-63) were selected. Lesions were divided into two groups according to operator experience (n = 42 restorations performed by a skilled operator, n = 48 restorations performed by five unexperienced operators) and further divided into two subgroups according to the adhesive system used: three-step etch-and-rinse (Optibond FL) or one step self-etch (G-Bond). Adhesives were applied according to manufacturers' instructions. Subjects underwent follow-up at 12, 24, and 36 months and restoration retention, enamel and dentin marginal integrity, marginal discoloration, caries occurrence, post-operative sensitivity, and preservation of tooth vitality were evaluated according to USPSH criteria. ANOVA test was performed to evaluate the influence of the adhesive system, the operator experience, and aging on restorations.Operator experience (expert vs. inexperienced), aging time (12, 24, or 36 months), and the adhesive system (self-etch vs. etch-and-rinse) all affected the results statistically, as did the interaction between the adhesive system and operator experience.

The aim of this in vitro study was evaluate the effect of application of synthetic hydroxyapatite on fiber post bond strength to radicular dentine. Forty, single-root teeth were endodontically treated and an 8 mm post space was prepared. Specimens were randomly placed in four groups (n = 10 in each) and treated using the following fiber post luting procedures: group 1, 17% EDTA + Panavia SA; group 2, 17% EDTA + Teethmate Desensitizer + Panavia SA; group 3, All-Bond Universal + Duo-Link Universal; and group 4, All-Bond Universal + Teethmate Desensitizer + Duo-Link Universal. Fiber posts were luted in the post space and light-cured for 120 s using a light-emitting diode (LED) lamp. After 7 d of storage at 37°C, the teeth were cut into 1-mm-thick slices, which were subjected to a push-out test until failure using a universal testing machine. Two specimens per group were prepared for scanning electron microscopy analysis. An energy-dispersive X-ray spectroscopy detector was used for elemental analysis of the specimen surface. The results were statistically analyzed using one-way anova. The fiber post bond strength was statistically significantly increased after the application of Teethmate Desensitizer to post space walls, either with a 10-MDP-containing self-adhesive cement or with a universal adhesive. Scanning electron microscopy and EDAX analysis showed that Teethmate Desensitizer created a calcium phosphate precipitate over post space dentinal tubules, which significantly improved the bond strength of the fiber post luted with 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-containing adhesive systems.

Introduction A coronal seal is fundamental for a positive outcome to endodontic therapy. In this in vitro study, we evaluated the adaptation of composite resins in postendodontic restorations using optical coherence tomographic (OCT) imaging. Our null hypothesis was that there would be no difference in marginal adaptation to the pulp chamber floor between resin composites of different viscosities. Methods Thirty intact upper molars extracted for periodontal reasons were selected, endodontically treated, and filled with gutta-percha. The excess gutta-percha was entirely removed from the pulp chamber floor, and teeth were randomly divided into 3 groups (n = 10) according to the material used for the restoration: group 1: 0.5-mm horizontal layer of flowable composite followed by nanohybrid composite, group 2: bulk layering of bulk fill flowable composite; and group 3: oblique layering of nanohybrid composite. The degree of adaptation to the cavity floor was assessed using OCT imaging, and images were analyzed with the software program ImageJ (National Institutes of Health, Bethesda, MD) to assess the marginal gap between the composite and the pulp chamber floor. Collected data were statistically analyzed using analysis of variance testing, and statistical significance was set at P

Purpose: To evaluate the influence of a three-step etch-and-rinse versus a two-step self-etch adhesive system on immediate post-operative sensitivity. Methods: In total, 204 subjects with one posterior tooth affected by a primary carious lesion were recruited. The subjects were randomly divided into two groups, based on the two multi-step adhesive systems used: Group A (All Bond 3) and Group B (Clearfil Protect Bond). The same skilled operator carried out the restorations using a nano-hybrid composite (Venus Diamond) in oblique stratification. Each increment was light-cured for 20 seconds with a LED lamp (Translux Power Blue). Subjects received a three-level thermal sensitivity questionnaire for post-operative sensitivity ratings. The evaluations were recorded daily for 7 days. Scores were analyzed using the McNemar test and postoperative trends were analyzed with the Friedman test (P< 0.05). All (100%) enrolled subjects completed the follow-up visits. There was no statistically significant difference between the two groups in post-operative sensitivity trends. In both groups, increased post-operative sensitivity was found at Dl, which then decreased significantly during the observation period. Results: The results of this in vivo study showed that both of the tested adhesives, etch-andrinse or self-etch, provided effective dentin sealing, preventing subjects from experiencing post-operative sensitivity in the treatment of medium-depth cavities.