Aim This observational cohort study aimed: (i) to determine retrospectively after a 1‐ to 12‐year follow‐up period, the strength and independence of the association of various patient‐, tooth‐ and treatment‐related prognostic variables with the outcome of root canal treatment in patients with pre‐therapeutic apical periodontitis; and (ii) to establish the concordance between those predictors evaluated by both cone‐beam computed tomography (CBCT) and digital periapical radiography (DPR). Methodology The study cohort included 125 teeth in 84 individuals. The postoperative clinical signs/symptoms, plus DPR/CBCT‐PAI estimations, were used to determine the healing outcome. For statistical analysis, results were dichotomized into completely healed periapical structures versus persistent disease cases. The association between candidate predictor variables with persistent disease was analysed individually and adjusted for confounders using a multivariate binary logistic regression model. Results The success rate was 53.6%. After logistic regression analysis, mandibular tooth location, periapical lesion size >10 mm, poor quality of the coronal restoration, lack of magnification/illumination, lack of disinfection of gutta‐percha, time elapsed to definitive coronal restoration >1 week and poor density of root canal filling remained as robust predictors of failures. Concordance between DPR and CBCT scores varied from moderate to almost perfect agreement. Conclusions The findings of this study suggest that several tooth‐ and treatment‐related predictor variables, including tooth location, periapical radiolucency size, quality of the coronal restoration, magnification/illumination, disinfection of gutta‐percha, time elapsed to definitive coronal restoration, as well as, the density of root canal filling may act strongly and independently for determining the root canal treatment outcome in teeth with pre‐therapeutic apical periodontitis.

The findings of this study suggest that whilst the quality of both the coronal restoration and the root-end filling might be the foremost prognostic variables in periradicular surgery, there are synergistic biological interactive and mutually confounding effects with respect to root-end resection bevel and preoperative signs and/or symptoms that may be also associated with an increased proportion of failures after periradicular surgery.

Root canal treatment and non-vital bleaching of teeth with pulp canal obliteration may represent a complex challenge to the clinician. This report describes the usefulness of the computer-assisted dynamic navigation system for the root canal treatment of two cases of teeth with a history of traumatic injury, extensively obliterated root canals and crown discoloration. Clinical and cone-beam computed tomographic evaluations were completed prior to procedures and 12 months after treatment. Both cases were treated using a computer-assisted dynamic navigation system coupled to a high-speed handpiece in order to establish the location and orientation of the partially obliterated canal and endodontic access route planning. The system allowed an accurate localisation of the root canal with a conservative access cavity. At the 12month recall examination, the patients continue to be symptom-free, with a normal appearance of the mucogingival complex, adequate restoration of the tooth colour and intact periapical structures.

No abstract

Background: Nickel–titanium (NiTi) instruments have represented a great technological development that enabled endodontists conforming irregular-shaped root canals. Notwithstanding, the repeated use of these instruments may lead to the fracture without any prior visible warning signs. This study aimed to evaluate how multiple clinical instrumentation/sterilization cycles of two NiTi mechanized instruments can affect their microstructural, microchemical, and mechanical characteristics. Materials and Methods: In this observational descriptive study, a total of 140 NiTi instruments, 70 ProTaper Gold® (PTG) and 70 WaveOne Gold® (WOG) were analyzed. For each brand system, instruments were evaluated in the as-received condition (n = 10) and after one (n = 20), two (n = 20), and three (n = 20) instrumentation/sterilization cycles. Intraoperative instrumentation parameters were recorded for all used instruments. Afterward, the files were examined using scanning electron microscopy and energy-dispersive X-ray microanalysis. All of the instruments were tensile-fatigue tested until rupture in order to calculate the mechanical tensile strength and the maximum elongation percentage for the samples. Statistical analysis was completed using Chi-square, Kruskal–Wallis H-, or Mann–Whitney U-tests with a statistical significance set at P < 0.05. Results: Significant increasing changes in surface topography (P < 0.05, Chi-square test) and chemical composition (P < 0.05, Kruskal–Wallis H-test) in both brand systems through instrumentation/sterilization cycles were detected. In addition, values of mechanical tensile strength and maximum elongation percentage increased significantly through instrumentation/sterilization cycles in the PTG group, whereas only the median values of mechanical tensile strength increased significantly in the WOG group (all P < 0.01, Kruskal–Wallis H-test). Conclusion: Although multiple instrumentation/sterilization cycles may render NiTi instruments more flexible and fatigue resistant, the significant changes detected in their surface topography and chemical composition should preclude their repeated clinical use in the routine endodontic practice as prevention for breakage.