Molar-incisor malformation (MIM) is a developmental dental anomaly primarily affecting permanent first molars, often accompanied by structural irregularities such as cervical mineralized diaphragms (CMDs) and furcal channels. These anatomical complexities present significant challenges for endodontic treatment. This case report presents the endodontic management of a maxillary first molar diagnosed with MIM-a condition for which root canal treatment has rarely been reported. The affected tooth exhibited characteristic features of MIM, including underdeveloped roots, CMD, and an open furcal channel. Initial canal negotiation revealed four buccal canals, but the palatal canal could not be located via conventional access. A separate access approach enabled successful identification, disinfection, and obturation of the palatal canal. Follow-up imaging showed healing of the periapical lesion and favorable clinical outcomes. This case highlights the diagnostic and technical challenges in managing MIM-affected teeth and underscores the importance of advanced imaging, tailored access strategies, and careful material selection to achieve successful endodontic outcomes.
Objectives This systematic review and meta-analysis aimed to evaluate the existing literature and quantitatively analyze the cyclic fatigue resistance of original and replica-like nickel-titanium endodontic files. Methods A comprehensive search was conducted across four electronic databases up to July 6, 2025, following PRISMA guidelines (PROSPERO: CRD420251086699). The methodological quality of included studies was assessed using criteria adapted from previous in vitro systematic reviews. Publication bias was evaluated using Egger’s test and the trim-and-fill method. A random-effects meta-analysis was performed to compare the cyclic fatigue resistance of original and replica-like files using time to fracture (TTF) and number of cycles to fracture (NCF) as outcomes. These were expressed as standardized mean differences (SMDs) with 95% confidence intervals (CIs). Heterogeneity was analyzed using the I² statistic. Results A total of 14 studies involving 1,276 endodontic files (nine original and 31 replica-like types) were included. Based on TTF values, replica-like files showed significantly greater cyclic fatigue resistance than original files (SMD, –0.845; 95% CI, –1.268 to –0.423; p < 0.001). However, NCF-based analysis revealed no statistically significant difference (SMD, –1.532; 95% CI, –3.615 to 0.550; p = 0.149). Conclusions Replica-like files exhibited cyclic fatigue resistance comparable to original instruments and may be considered potential alternatives. However, due to high heterogeneity and methodological variability, these findings should be interpreted with caution.
Objectives:This in vitro study aimed to assess the fracture resistance of simulated stages of root maturation following regenerative endodontic treatment using a cyclic loading method. Methods:Ninety extracted maxillary central incisors were randomly allocated into three experimental groups representing different stages of root development, following revitalization: Group A for completely immature teeth immediately after treatment; Group B for teeth with apical closure, and Group C for teeth with apical closure and wall thickening. Two control groups were also included: Group D for intact teeth and Group E for simulated immature teeth without the bioceramic material. Following simulation of immature apices and treatment with a bioceramic material, all specimens were subjected to cyclic loading using a step-stress fatigue protocol until failure. The number of cycles to fracture and the peak load were recorded and statistically analyzed. Results:Statistically significant differences in loading forces were observed between the negative control group (Group D) and Groups A, B, and E (p < 0.05). However, no statistically significant differences were detected among the experimental groups. These results indicate that apical closure and dentinal wall thickening alone did not substantially improve mechanical reinforcement under cyclic loading conditions. Conclusions:Although intact teeth exhibited superior mechanical performance, apical closure and wall thickening alone were insufficient to enhance reinforcement under cyclic loading.
Objectives This study aimed to assess geometric characteristics in canal preparation using nickel-titanium (NiTi) files used for minimal invasiveness. Methods Thirty J-shaped simulated canals in resin blocks were instrumented with either TruNatomy (TR; Dentsply Sirona), EndoRoad (ER; Maruchi), or ProTaper Ultimate (PTU; Dentsply Sirona). The simulated canal blocks were scanned using microcomputed tomography before and after instrumentation. The scanned images were reconstructed, and the canal surface area was measured from 0.5 to 6.5 mm from the apex. Three-dimensional representative models of each group were rendered. The data were statistically analyzed using one-way analysis of variance and Kruskal-Wallis test at 95% significance level. Results TR showed a superior ability to maintain the canal’s center. TR demonstrated comparable apical preparation to PTU. ER showed a smaller and limited apical preparation than other systems, with a tendency for canal preparation toward the inner side of the curvature. PTU featured the largest prepared apical size among the file groups and tended to straighten the curvature by preparing the canal more towards the outward side. The surface area instrumented using each NiTi file showed statistically significant differences among the three groups at all levels except 0.5, 2.0, and 3.5 mm from the apex (p < 0.05). There was no statistically significant difference between TR and PTU at a level of 0.5 mm from the apex (p > 0.05). Conclusions While PTU is suitable for general canal preparation to facilitate irrigation and intracanal medication, TR and ER excel in preserving canal centering with minimal concern for canal transportation by minimally invasive preparation.
Objectives This study aimed to compare the magnitude of pulp space narrowing over time—measured as the change in pulp/tooth proportion from baseline—between mandibular molars treated with different types of vital pulp therapy (VPT) and their contralateral sound molars (controls). This study also investigated factors influencing the magnitude of pulp space narrowing in molars that have undergone VPT. Methods This retrospective cohort study involved the assessment of bitewing radiographs of VPT-treated molars and controls at baseline and follow-up. Using reference points and lines on the radiograph, pulp/tooth proportions were measured by examiners. The intraclass correlation coefficient (ICC) was used to report examiner reliability. The changes in pulp/tooth proportions from baselines were compared between subgroups using multilevel mixed effect linear regression and the Wald test. Results A total of 382 bitewing radiographs from 134 teeth were included. The follow-up period ranged from 6 to 84 months (mean, 27.12 ± 17.67 months). ICC values indicated good to excellent examiner reliability. Compared to the controls, changes in pulp/tooth proportion from baselines, indicating pulp space narrowing, were significantly greater in teeth with partial pulpotomy (at pulp chamber width) and coronal pulpotomy (at pulp canal width). Factors affecting the magnitude of pulp space narrowing included the more invasive type of VPT and the more severe preoperative diagnosis. Conclusions The magnitude of pulp space narrowing was greater in VPT-treated molars than in controls. The more invasive type of VPT and severe preoperative diagnosis were factors contributing to the magnitude of pulp space narrowing.
