Search Results (254)

Background/Objectives: The aim of this study was to compare the effectiveness of the Reciproc Blue (RB) and MicroMega Remover (MR) systems in removing root canal filling material and to evaluate the effect of passive ultrasonic irrigation (PUI) on remaining filling material (RFM) using micro-computed tomography (micro-CT)-based three-dimensional (3D) analysis. Methods: Forty single-rooted mandibular premolar teeth were included in the study. The root canals were prepared up to size F2 using the ProTaper Gold rotary file system and obturated with the lateral compaction technique. After the initial micro-CT scan, the teeth were randomly divided into four groups: Group RB, Group MR, Group RB + PUI, and Group MR + PUI (n = 10). Following retreatment, a second micro-CT scan was performed. The percentage of RFM was calculated, and statistical analyses were performed using Kruskal–Wallis and Mann–Whitney U tests with Bonferroni correction. A rank-based factorial analysis was additionally performed (p < 0.05). Results: RFM was observed in all groups. No significant difference was found between the RB (7.37%) and MR (7.31%) systems (p > 0.05). However, the groups treated with PUI (RB + PUI and MR + PUI) showed significantly lower RFM values than the groups without PUI (p = 0.001). Factorial analysis revealed no significant effect of file system or file system × PUI interaction, whereas PUI significantly reduced RFM (p < 0.001). Conclusions: The RB and MR systems demonstrated similar effectiveness in removing root canal filling material. Although complete canal cleanliness could not be achieved, under the in vitro conditions of the present study, PUI significantly reduced the amount of micro-CT-measured RFM. Full article

Background and Objectives: Warm injectable gutta-percha techniques may improve three-dimensional filling of complex canal anatomy, but heat transfer to the external root surface may threaten periodontal tissues when the 47 °C threshold is exceeded. This in vitro study quantified external root-surface temperature changes during obturation with the Woodpecker FI-G/FI-P system and compared manufacturer preset temperatures with actual device output. Materials and Methods: Twenty extracted single-rooted human teeth standardized to 18 mm were prepared and assigned to obturation at 180 °C (Group A, n = 10) or 230 °C (Group B, n = 10). Infrared thermography recorded coronal, middle, and apical root-surface temperatures. A second device-based experiment measured FI-G and FI-P output at preset temperatures of 150 °C, 180 °C, 200 °C, and 230 °C. Results: The 230 °C setting produced significantly higher middle-third temperatures than the 180 °C setting (41.84 ± 5.52 °C vs. 36.99 ± 3.21 °C; p = 0.027; Cohen’s d = 1.07), whereas coronal and apical differences were not significant. The highest external root-surface value was 49.6 °C, and 3/10 specimens obturated at 230 °C exceeded 47 °C in the middle third. A significant coronal-to-middle gradient reversal was observed at 230 °C (p = 0.045). Device measurements showed strong attenuation between preset and output temperatures: at 230 °C, the FI-G tip base reached 150.0 °C but the tip apex reached 51.3 °C, while FI-P plugger tips reached 120.0 °C. Conclusions: The 180 °C setting produced a more predictable thermal profile, whereas 230 °C increased localized middle-third overheating risk. These in vitro findings support cautious temperature selection, especially in teeth with reduced dentin thickness or compromised root anatomy. Full article

The aim of this study was to evaluate the effect of two laser-assisted disinfection techniques on the porosity and bond strength (BS) of a new premixed calcium silicate sealer. Forty extracted human single-rooted premolars with one root canal were prepared up to 50/05. Samples were randomly assigned to the groups (n = 10 each): 1. shock wave-enhanced emission of photoacoustic streaming (SWEEPS) (20 mJ, 15 Hz, 0.60 W, pulse duration 25 µs), 2. diode laser (975 nm, 1.5 W), 3. conventional needle and syringe irrigation (CI), and 4. control (C), with no final irrigation protocol. Root canals were filled with a premixed calcium silicate sealer using the single-cone obturation technique. Micro-CT scans were performed after two weeks to determine the presence of voids in the filling. Dentinal discs from the middle third were prepared for push-out testing. Kruskal–Wallis and post hoc Dunn tests were used, with significance set at 5%. Micro-CT analysis detected porosity in all samples, with no significant differences among the groups (p > 0.05). SWEEPS showed the highest BS values (median 3.233 MPa) and outperformed CI and C (median 1.923 and 1.989 MPa) (p < 0.05) overall. SWEEPS enhanced the BS compared with CI. Voids were present in all experimental groups. Full article

Objectives: Commercial artificial teeth (AT) and three-dimensional printed teeth (3DPT) have been increasingly used in preclinical endodontic education; however, limitations regarding anatomical realism, tactile sensation, and procedural simulation continued to be reported. This study assessed students’ and evaluators’ perceptions regarding AT and PolyJet™ 3DPT fabricated with RGD525™, compared with natural teeth (NT), together with the quality of endodontic procedures performed using both artificial models. Methods: Undergraduate dental students with no previous experience using AT or 3DPT performed standardized endodontic procedures on both artificial models. Students and evaluators completed questionnaires regarding anatomical realism, tactile sensation, radiographic characteristics, educational applicability, and model preference. Procedural quality and errors were independently assessed radiographically by evaluators. Results: AT received more favorable perceptions regarding external anatomy, whereas 3DPT were more positively evaluated for internal anatomy, radiopacity, resistance of root canal walls and tactile sensation during instrumentation (p ≤ 0.002). NT remained the preferred training model, followed by 3DPT, while AT received the lowest preference ratings (p < 0.001). Evaluators consistently perceived 3DPT as more similar to NT than AT. Regarding treatment outcomes, 3DPT showed significantly higher scores for endodontic preparation, verifier fitting, and root canal filling (p < 0.05), while presenting significantly fewer procedural errors than AT (p < 0.001). Conclusions: PolyJet™ 3DPT fabricated with RGD525™ demonstrated promising applicability for preclinical endodontic training, combining favorable perceptions, fewer procedural errors, and potential for low-cost large-scale in-house production. Nevertheless, improvements in material realism and tactile simulation are still required. Full article

Background: This study evaluated the effects of flattening the side of the bending resistance and torsional resistance of nickel–titanium files through finite element analysis of a novel flattened file and a standard nonflattened file. Methods: For torsion analysis, the tip of the file was fixed at 3 mm, generating a torque of 2.5 N·mm at the handle. For bending analysis of curved root canals (45° and 60°), the handle was kept fixed, a force of 1 N was applied at the tip, and the file was fixed at 3 mm. Results: The standard nonflattened file exhibited better torsional resistance. In contrast, the novel flattened file showed improved flexibility under 45° bending. Under this condition, lower maximum von Mises stress was observed in the flattened design compared with the standard file. At 60° bending, stress distribution varied with loading orientation, and higher stress concentrations were observed in the flattened file under specific bending directions, indicating reduced bending resistance under large deformation conditions. Conclusions: Since lateral flattening may reduce the cyclic resistance of files, caution should be exercised in the clinical use of such files. Full article

Background: The primary goal of root canal treatment is the prevention and healing of apical periodontitis through the meticulous elimination of pathogenic bacteria and infected tissues. Within this framework, apical patency remains a fundamental yet debated clinical concept. Objectives: This review aims to evaluate the clinical significance of maintaining apical patency, its influence on postoperative discomfort, and the technical strategies required for predictable negotiation. Methods: We performed a comprehensive review of existing literature, including clinical studies and recent meta-analyses, focusing on the correlation between patency maneuvers and postoperative pain, the role of preoperative CBCT imaging, and the efficacy of specialized negotiation instruments and motor kinematics. While patency facilitates thorough debridement, evidence regarding its impact on postoperative pain is conflicting, with recent meta-analyses suggesting it may actually alleviate discomfort intensity. Preoperative CBCT was identified as essential for identifying complex anatomy, such as the MB2 canal. Furthermore, the use of specialized files and reciprocating motor modes enhances the predictability of glide path establishment. Conclusions: Although failure to achieve patency does not always dictate a negative outcome, it is associated with improved long-term healing. Clinicians should prioritize “Anatomical Patency”—respecting original morphology—over forceful “Operative Patency” to ensure procedural integrity and clinical success. Full article

This study aimed to evaluate the aging effect (6 and 12 months), relative to baseline (0 months), on the dimensional accuracy, morphological stability, and shaping behavior of PolyJet™ 3D-printed teeth (3DPT) produced in two printing orientations (X and Y axes). Specimens (XA0, XA6, XA12, YA0, YA6, YA12) were analyzed using microcomputed tomography before and after root canal preparation with the ProTaper Gold^® system. Preoperative analysis included canal volume, centroid, total tooth volume, and total tooth area. Aging-related changes were observed, with significant differences between XA0 and XA12 (p < 0.05), whereas no differences were detected among Y-axis groups (p > 0.05). These findings indicate that X-axis specimens are not comparable over time, while Y-axis specimens maintain baseline consistency. Postoperative evaluation revealed significant differences across aging conditions for most endodontic preparation parameters. Within the limitations of this study, aging had a limited effect on dimensional accuracy but influenced the shaping behavior of 3DPT. Based on these findings, future studies using PolyJet™ 3DPT should report the printing batch and the storage time between fabrication and experimental use, as these factors may influence the comparability and reliability of the results. Full article

Background: Successful healing of chronic apical periodontitis after endodontic treatment requires a reduction in the size of the radiolucent area and the healing of the bone. This study aimed to compare the effects of different irrigation activation techniques on healing in single-rooted mandibular premolar teeth with periapical lesions of endodontic origin. Methods: A total of 132 systemically healthy patients with mandibular single-rooted premolar teeth and a periapical index (PAI) score ≥ 3 were assigned to five experimental groups (Sonic activation, Passive ultrasonic irrigation, Photon-Induced Photoacoustic Streaming, Shock Wave Enhanced Emission Photoacoustic Streaming and Manual dynamic activation) and a control group (Conventional Syringe Irrigation). After access cavity preparation, the canals were prepared up to three sizes larger than the initial apical diameter with 5 mL of 2.5% NaOCl used between each file. Final irrigation was performed via the assigned activation system. The root canals were obturated with gutta-percha in a single visit. The effects of the activation systems on healing were compared at 1-year follow-up. The primary outcome measure was the change in lesion diameter. PAI score and fractal dimension (FD) were evaluated as secondary outcomes. Results: At the 1-year follow-up, FD values significantly increased, PAI scores and lesion size decreased in all groups compared with baseline (p < 0.001). However, the increase in FD was comparable among the irrigation groups (p > 0.05). In contrast, lesion size reduction and PAI-based healing rates favored the laser-activated groups. The PAI scores and lesion size in the control group were significantly greater than that in the laser groups (p < 0.05). Conclusions: At the 1-year follow-up, all the groups presented similar FD increases, while the laser irrigation groups presented significantly greater reductions in lesion size than did the control group. Full article

The introduction of calcium-silicate-based sealers has renewed interest in simplified obturation protocols such as the single-cone technique, although warm techniques, including carrier-based obturation, are still considered the gold standard. The aim of this in vitro study was to compare the quality of root canal obturation achieved with single-cone and carrier-based techniques when used with the same calcium-silicate-based sealer. Thirty extracted mandibular molars were prepared using a standardized rotary instrumentation protocol and randomly assigned to two groups (n = 15 each): Group A was obturated using a carrier-based technique (Soft-Core obturators), while Group B was obturated with the single-cone technique. All canals were filled with the same calcium-silicate-based sealer (NeoSEALER Flo). Micro–computed tomography was used to evaluate the number and volume of voids of the obturation. Quantitative analysis showed that Group A exhibited a significantly lower number of voids (9.0 ± 5.0) and reduced total void volume (2.58 ± 0.8 mm³) compared with Group B (22.0 ± 10.1 voids; 4.71 ± 1.1 mm³; p = 0.00002 and p = 0.0026, respectively). Qualitative analysis confirmed that carrier-based obturation achieved a denser and more homogeneous filling, while the single-cone technique showed larger voids mainly in the coronal and middle thirds. Both techniques provided a reliable apical seal. Within the limitations of this in vitro study, carrier-based obturation demonstrated superior overall filling quality compared with the single-cone technique when used with a calcium-silicate-based sealer, particularly in the middle and coronal regions of the root canal. Full article

Cone-beam computed tomography (CBCT) is widely utilized in endodontics for evaluating root canal shaping outcomes, offering critical three-dimensional imaging capabilities. This study aims to assess the differences in apical and root canal preparation across various instrumentation techniques using CBCT. A systematic search of the Medline database (via PubMed) and Web of Science was performed up to 12 April 2025, yielding a total of 70 studies, with 45 full-text articles assessed for eligibility; 28 were included in the review. Studies showed great heterogeneity in experimental design, anatomical variables, and outcome measurements. The results indicate that rotary instruments, such as ProTaper Next^® and XP-Endo Shaper^®, were reported more frequently or showed favorable shaping trends in individual studies. Although rotary systems often appeared advantageous, conclusions were limited by study design variability and a lack of correlation with clinical outcomes. The evidence highlights the need for standardized methodologies and further research, especially on manual techniques. CBCT remains a valuable research tool despite inherent spatial resolution limitations. Full article

Background and Objectives: The anatomically demanding structure of curved root canals increases the technical difficulty of retreatment procedures. This study aimed to evaluate the retreatment efficacy of various rotary and reciprocating instruments in curved root canals obturated with cold and warm techniques regarding root canal filling material removal, apical transportation, and retreatment time. Materials and Methods: Sixty-four curved mesial root canals of mandibular molars with Vertucci type IV morphology were prepared using the ProTaper Gold system and obturated with AH Plus sealer using either the single-cone (SC) (n = 32) or continuous wave vertical compaction (CWC) (n = 32) technique. Each group was divided into four subgroups (n = 8) and retreated using MicroMega Remover (MM Remover), ProTaper Universal Retreatment (PTUR), Reciproc (Rec), and Hedstrom file systems. Micro-computed tomography was used to assess residual filling material volume and apical transportation. The time required for retreatment was recorded. The level of statistical significance was set at p < 0.05. Results: Across both obturation techniques, the MM Remover and PTUR groups demonstrated shorter retreatment times compared with the CWC–Hedstrom group (p < 0.05). No statistically significant differences were observed among the file systems in terms of filling material removal and apical transportation (p > 0.05). Conclusions: All tested instruments effectively preserved root canal anatomy within clinically acceptable apical transportation limits. The MM Remover and PTUR systems achieved significantly shorter retreatment times, indicating clinical advantages in efficiency. None of the evaluated systems achieved complete removal of the filling materials in either obturation technique. This study provides one of the first comparative evaluations of the MM Remover system, supporting its applicability in complex canal configurations. Full article

Objectives: This study evaluated the effect of three root canal filling material (RCFM) removal techniques—mechanical, thermo-mechanical, and chemico-mechanical—on the micro push-out bond strength of fiber posts to root dentin in endodontically treated teeth. Materials and Methods: Forty-five single-rooted human premolars were endodontically treated and randomly allocated into three groups (n = 15) according to the RCFM removal technique used during post-space preparation: mechanical, thermo-mechanical, or chemico-mechanical. Fiber posts were luted using a dual-cure resin cement. Roots were embedded in resin and sectioned into coronal, middle, and apical thirds. Micro push-out bond strength was measured using a universal testing machine. Failure modes were examined under a stereomicroscope and validated using scanning electron microscopy. Statistical analysis used two-way ANOVA and Chi-square tests (α = 0.05). Results: Both the thermo-mechanical and mechanical groups showed significantly higher bond strength values than the chemico-mechanical group (p < 0.001). Across all groups, the coronal third recorded the highest bond strength, while the apical third presented the lowest values (p < 0.001). Adhesive failure at the dentin–cement interface was the most frequent failure mode. Conclusions: The gutta-percha removal technique and the root canal region significantly influence fiber-post bond strength. Solvent-based chemico-mechanical methods may adversely affect adhesion quality. Clinical Relevance: Thermo-mechanical and mechanical removal techniques may provide more reliable post retention during retreatment procedures, improving adhesion and reducing the risk of post debonding in daily practice. Full article

This study analyzed how different downward loads and rotational kinematics influence NiTi rotary instrumentation outcomes. Heat-treated NiTi instruments were used to prepare extracted human single-rooted premolars with a moderate canal curvature. Instrumentation was performed using an automated endodontic instrumentation device with controlled downward loading and torque/force sensing, under different downward load settings (1, 2, and 3 N), employing either continuous rotation (CR) or optimum torque reverse (OTR) motion, which is a torque-sensitive reciprocation. Instrumentation was completed without instrument fracture or ledge formation in all six groups. OTR-3N specimens displayed a significantly lower upward force (i.e., screw-in force) than OTR-2N specimens (p < 0.05). OTR-1N specimens required a significantly longer instrumentation time than CR-1N specimens and the other OTR specimens (p < 0.05). At 1 mm from the apex, CR-2N specimens showed a significantly larger canal-centering ratio (i.e., larger deviation) than OTR-2N specimens (p < 0.05). Overall, applying a downward load of 2–3 N in OTR mode provided shaping efficiency similar to CR, but with a reduced screw-in force and enhanced canal-centering in the apical region, supporting the use of OTR as a promising alternative to CR for curved canal preparation using heat-treated NiTi instruments. Full article

This study evaluated the push-out bond strength (PBS) and failure modes of fiber posts cemented with silane-containing self-adhesive resin cement (SARC) compared with conventional SARC and universal adhesive strategies, considering the effects of root section and aging. Ninety single-rooted human premolars were equally assigned to three cementation protocols: silane-containing SARC (PANAVIA SA Cement Universal), conventional SARC (RelyX Universal), and universal adhesive plus SARC (Scotchbond Universal Plus + RelyX Universal). Each group was divided into two aging subgroups: 24 h water storage and thermal cycling (10,000 cycles between 5 °C and 55 °C, 30 s dwell time; n = 15). After root canal treatment and post space preparation, glass fiber posts were cemented, and each root was sectioned to obtain six slices. PBS was measured using a push-out test, and failure modes were examined under stereomicroscopy. Data were analyzed using three-way ANOVA, post hoc tests, Spearman’s correlation, and logistic regression (α = 0.05). Cement type, root section, and aging significantly influenced PBS (p < 0.001). PBS decreased from coronal to apical sections, and thermal cycling reduced PBS in all groups. The universal adhesive plus SARC achieved the highest PBS, while conventional SARC had the lowest PBS. Cementdentin adhesive failures (FM2) predominated overall, with proportions varying between 43% and 90%, and higher PBS values were associated with fewer FM2 failures. The combination of a universal adhesive with SARC provided superior bonding compared to simplified protocols. Although silane-containing SARC improved bonding relative to conventional SARC, durable adhesion to radicular dentin remains challenging, particularly in apical regions. Full article

This study synthesizes novel photosensitizer calcination betaine hydrochloride carbon dots (CBCDs) to address the critical challenge of Enterococcus faecalis (E. faecalis) biofilms, a major cause of root canal treatment failure. To this end, this study investigates the effective elimination via reactive oxygen species (ROS) mediated by these CBCDs. CBCDs were prepared by calcining betaine hydrochloride and rigorously characterized for their structural and chemical properties using transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Their optical characteristics were also thoroughly analyzed through UV-Vis and fluorescence spectroscopy. The RNO-ID assay was performed to explicitly confirm ROS production, particularly verifying significant singlet oxygen (¹O₂) generation. Bactericidal efficacy of the CBCDs was comprehensively evaluated against planktonic E. faecalis and its formed biofilms. Live/dead staining was subsequently performed to observe their state after treatment. As a result, TEM confirmed nanosized CBCDs, and FTIR/XPS analyses identified crucial functional groups. Colony Forming Unit (CFU) assays revealed a dose-dependent reduction in E. faecalis viability, achieving complete eradication at 200 mg/L under light irradiation. Complete cell death and inactivation of the formed biofilms with increasing CBCD concentrations were also strongly evidenced by red fluorescence. The obtained results underscore CBCDs as highly effective photodynamic agents for the robust elimination of E. faecalis biofilms, offering a promising new strategy to combat persistent oral infections. Full article