Abstract Sodium hypochlorite (NaOCl) is a widely used endodontic irrigant; however, accidental extrusion beyond the apical foramen can result in severe soft tissue injury. This report describes a NaOCl accident in a 32-year-old medically fit male who was referred for completion of root canal treatment of the right mandibular first premolar associated with a chronic sinus tract. The patient’s chief concern was a persistent sinus tract and discharge despite previous treatment. Clinical examination and tracing of the sinus tract through a periapical radiograph confirmed a chronic apical abscess in a tooth with previously initiated therapy. During irrigation with 5.25% NaOCl through a side-vented needle under rubber dam isolation, the patient experienced immediate pain and bleeding, consistent with NaOCl extrusion. A cone beam computed tomography scan confirmed intact root anatomy with no apical perforation. Prompt management included cessation of NaOCl irrigation, copious saline irrigation, incision and drainage, calcium hydroxide placement, and close follow-up. Subsequent visits demonstrated complete healing of the sinus tract, and the tooth was obturated and restored. Six-year follow-up showed a functional, asymptomatic tooth with radiographic evidence of complete periapical healing. This case emphasizes the importance of early recognition, appropriate management, and preventive strategies for NaOCl accidents, particularly in teeth with sinus tracts and complex anatomy.
Abstract Introduction: The current study investigated the anatomical relationship between the root apices of mandibular posterior teeth and the mandibular canal, assessing the impact of gender and age on these parameters through cone-beam computed tomography (CBCT) in an Eastern Saudi Arabian subpopulation. Materials and Methods: In the current retrospective study, 102 CBCT scans of Saudi patients (57 females and 45 males; aged 20–60 years) with intact mandibular posterior teeth were analyzed. Scans were obtained using a NewTom scanner and analyzed in multiplanar reconstruction views. The distance between the root apex and the mandibular canal was assessed for both the first and second molars, as well as the premolars. Two endodontists and one oral radiologist performed measurements, demonstrating excellent intra- and interexaminer reliability (intraclass correlation coefficient = 0.95). Independent t -test and Pearson’s correlation were used for gender and age comparisons. The level of significance ( P value) was set at 0.05. Results: Males showed greater mean root apex-to-mandibular canal distances for all teeth, especially in premolars. Significant gender difference was observed at the left second molar (Left mandibular second molar [LL7]; P = 0.043), with borderline significance at the left first premolar (Left mandibular first premolar [LL4]; P = 0.050). Patient age did not significantly correlate with root-to-canal distance. Conclusion: The study identified gender-based differences in the proximity of mandibular posterior tooth roots to the mandibular canal, with females exhibiting shorter root-to-canal distances at the left second molar and first premolar. In addition, the distance to the mandibular canal was not significantly correlated with age.
Abstract Introduction: Reciprocating nickel–titanium (NiTi) instruments demonstrate improved cyclic fatigue resistance compared with continuous rotation, largely due to thermomechanical processing that modifies phase transformation behavior. This systematic review synthesized metallurgical evidence on reciprocating NiTi instruments and examined the relationship between phase constitution and mechanical performance under clinically relevant temperature conditions. Materials and Methods: Six electronic databases and gray literature were searched. Laboratory studies evaluating phase transformation and metallurgical characteristics of reciprocating NiTi instruments using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, or transmission electron microscopy were included. Considerable heterogeneity was observed in instrument systems, temperature protocols, and reported outcomes. Therefore, meta-analysis was not performed. Findings were synthesized narratively. Results: Fourteen studies met the inclusion criteria. Heat-treated instruments exhibited distinct transformation temperature profiles, with several systems retaining martensitic and/or R-phase fractions at intracanal temperature (34°C). Instruments with Af temperature near or above intracanal temperature were generally more flexible and demonstrated greater cyclic fatigue resistance. In contrast, instruments predominantly austenitic at this temperature showed increased stiffness and shorter fatigue life. Mechanical behavior reflected interactions among phase constitution, instrument geometry, and surface characteristics, including manufacturing defects that may act as crack initiation sites. Conclusions: Phase constitution at intracanal temperature is a major determinant of reciprocating NiTi instrument performance. Heat-treated systems that retain martensitic and/or R-phase fractions near clinical temperature generally demonstrate greater flexibility and improved cyclic fatigue resistance. However, performance is also strongly influenced by instrument design and surface integrity.
Abstract Introduction: Dentin solubility influences the durability of endodontic treatment, as excessive demineralization may compromise long-term tooth stability. Trace element incorporation has been shown to alter dentin mineral properties, but systematic evaluation of their effects remains limited. This study aimed to develop a digital twin model to predict dentin solubility in response to trace element incorporation to optimize endodontic biomaterials. Materials and Methods: Thirty dentin specimens were treated with trace elements, and the solubility was measured under controlled conditions. The five elemental concentration predictors were standardized using StandardScaler. A Random Forest regression model was trained on 80% of the data and evaluated on the remaining 20% as a holdout test set, with performance assessed using mean squared error (MSE) and coefficient of determination metrics. Feature importance analysis identified the most influential elements. Results: The model achieved strong predictive performance ( R 2 = 0.74; MSE = 0.031). Feature importance analysis identified strontium and barium as the most influential predictors of solubility (26% and 23% of model importance), and produced the greatest reduction in solubility (6.00% ±0.16% and 6.20% ±0.16%, respectively) compared to control (7.10% ±0.16%). One-way analysis of variance confirmed statistically significant differences among groups ( P < 0.0001), and Tukey post hoc testing validated that all trace element groups differed significantly from control ( P < 0.001). Conclusions: Within the limits of this pilot study, the digital twin model was able to predict dentin solubility based on trace element composition and to identify elements associated with reduced solubility. These findings support the feasibility of using data-driven modeling as a screening tool to guide future studies in endodontic biomaterial development.
Abstract Introduction: This study assessed the effectiveness of different solutions in reestablishing apical patency during nonsurgical endodontic retreatment performed by a senior undergraduate dental student. Materials and Methods: 54 extracted human mandibular premolars with straight canals were prepared and obturated using a gutta-percha cone placed 2 mm short of the working length, ensuring that the apical 2 mm were filled exclusively with AH Plus sealer. After 5 weeks, retreatment was performed using the ProTaper retreatment system. The teeth were randomly assigned to three groups ( n = 18) according to the solution used: 3% sodium hypochlorite (NaOCl – control), orange oil (OOil), and a mixture of methylethylketone (MEK) with tetrachloroethylene (TCE). The data were analyzed using the Kruskal–Wallis and Fisher’s exact tests. Results: Patency was successfully re-established in 100% of the OOil group, 50% of the NaOCl group, and 72.2% of the MEK/TCE group, with the corresponding median times of 36 s, 44 s, and 118 s. No statistically significant differences regarding time were observed between groups. There was a significant association between the groups and the success rate of apical patency reestablishment, with the OOil and MEK/TCE groups showing higher success. Conclusions: Apical patency in straight canals obturated with AH Plus sealer can be more effectively achieved using solvents such as OOil or a MEK/TCE mixture, by a senior undergraduate student.
