Search Results (234)

This systematic review aimed to evaluate whether cross-sectional geometry is associated with cyclic fatigue resistance of nickel–titanium (NiTi) endodontic instruments and to identify the geometric and materials-related features most frequently associated with improved fatigue performance. The protocol was prospectively registered on the Open Science Framework (OSF). PubMed, Scopus, Embase, Web of Science, and WorldCat were searched in April 2026 in accordance with PRISMA 2020. Eligible studies were comparative in vitro investigations that explicitly evaluated cross-sectional geometry or a related geometric parameter as a prespecified study factor and reported quantitative cyclic fatigue outcomes. Of 107 screened records, 66 full-text reports were assessed and 23 studies were included in the qualitative synthesis. Twenty-two studies had a medium risk of bias and one had a low risk of bias according to the Quality Assessment Tool for In Vitro Studies (QUIN). Cyclic fatigue resistance was most often reported as time to fracture or number of cycles to failure. Instruments with reduced metal mass, smaller core volume, lower cross-sectional area, and greater flexibility tended to demonstrate higher fatigue resistance in curved canals. S-shaped and double-S-shaped cross-sections were most consistently associated with favorable outcomes; however, this association is more plausibly related to reduced bending stiffness and canal-wall contact forces than to increased intrinsic material fatigue strength. Flat-side designs did not show a consistent advantage. The evidence was limited by heterogeneous testing protocols and residual confounding by alloy, heat treatment, taper, manufacturing, surface condition, and kinematics. No meta-analysis or quantitative dimensional correlation was feasible because testing conditions and detailed geometric parameters were inconsistently reported. Full article

Background/Objectives: Pulp necrosis in immature permanent teeth arrests root development, leaving an open apex, thin, divergent dentinal walls, and an unfavorable crown-to-root ratio that predisposes the tooth to fracture and complicates endodontic management. An apical barrier using hydraulic calcium silicate cements has become the first-line orthograde approach for these teeth when regenerative procedures are not indicated or feasible. This narrative review synthesizes current evidence on the complete clinical pathway for apical barrier placement in immature permanent teeth, with particular emphasis on the procedural determinants of barrier formation. It also critically appraises where the evidence is robust and where it remains uncertain. Methods: The relevant English-language literature on root development, the etiology of pulp necrosis in immature teeth, diagnosis, isolation, apical barrier methods, calcium silicate materials, and treatment outcomes was reviewed through targeted searches of PubMed/MEDLINE, Scopus, Web of Science, the Cochrane Library, and Google Scholar through June 2026. The literature search was completed in June 2026; therefore, studies published after this date were not included. Evidence was narratively synthesized according to the clinical sequence of diagnosis, treatment selection, isolation, disinfection, barrier formation, restoration, follow-up, and evidence gaps. Throughout, an explicit distinction was maintained between clinical and laboratory evidence. Results: Sensibility testing is widely considered unreliable in immature teeth, complicating diagnosis. Isolation is often challenging because of traumatic crown loss. Successful treatment depends on adequate chemical disinfection, judicious minimal instrumentation, a well-condensed apical barrier of at least 4–5 mm, and a definitive coronal seal that also addresses the weak cervical dentin. Calcium silicate cements—principally MTA, Biodentine, and pre-mixed bioceramic putties—achieve high clinical success. Observational evidence further suggests, as a hypothesis requiring prospective confirmation, that material choice may be less decisive than operator experience and the quality of the coronal restoration. Conclusions: Apical barrier placement with hydraulic calcium silicate cements is a predictable orthograde preservation approach for non-vital immature permanent teeth, particularly when regenerative endodontic procedures are not indicated, not feasible, or unlikely to yield predictable clinical outcomes. Well-designed randomized clinical trials with standardized reporting are needed. Full article

Objectives: To compare the geometric design, metallurgical properties, mechanical performance, and irrigation dynamics of Reciproc Minima (M20 and M25) and Reciproc Blue R25 instruments. Methods: One hundred and eighty instruments (n = 60/group) were evaluated. Geometry was analyzed using stereomicroscopy, scanning electron microscopy, and 3D surface scanning. Metallurgical characteristics were assessed by energy-dispersive X-ray spectroscopy and differential scanning calorimetry. Mechanical performance tests (n = 10/group) included cyclic fatigue, torsional resistance, bending resistance, buckling resistance, and cutting efficiency. Irrigation dynamics were examined through computational fluid dynamics simulations based on a micro-CT-derived mandibular molar model prepared according to each system and combined with open-ended, side-vented, or double side-vented needles. Data were analyzed using one-way ANOVA or Kruskal–Wallis tests (α = 0.05). Results: The results showed that blade dimensions increased progressively from Minima M20 to Reciproc Blue R25. All instruments had S-shaped cross-sections and non-active tips. Energy-dispersive spectroscopy confirmed near-equiatomic NiTi composition, and similar phase transformation temperatures were observed across groups. Minima M20 showed the highest cyclic fatigue resistance (p < 0.0001), whereas Minima R25 exhibited greater angular deflection (p < 0.0001). Reciproc Blue R25 had the highest buckling resistance and lowest flexibility (p < 0.0001). M25 showed the lowest axial force, indicating the numerically highest cutting efficiency, but it did not differ significantly from Reciproc Blue R25 (p > 0.05). No needle delivered irrigant to working length. The open-ended needle achieved greater apical penetration, particularly with Reciproc Blue R25. Minima M20 generated the highest wall shear stress, and Reciproc Blue R25 the lowest apical pressure. Conclusions: Reciproc Minima and Reciproc Blue R25 showed similar metallurgical characteristics; however, differences in geometric design resulted in distinct mechanical behaviors and irrigation fluid dynamics. These findings suggest that low-taper reciprocating instruments may represent a conservative alternative in anatomically challenging canals, while clinicians should consider the associated differences in mechanical behavior and irrigation dynamics when selecting the most appropriate instrument. Full article

Bioceramic sealers have gained widespread acceptance in contemporary endodontics due to their favorable biological properties, dimensional stability, and bioactivity. However, their strong adhesion to dentinal walls and penetration into dentinal tubules may complicate removal during endodontic retreatment procedures. Additionally, the obturation technique may influence both the retreatability of root canal filling materials and the bond strength of sealers and resins to radicular dentin. Methods: One hundred extracted human single-rooted teeth were instrumented using the WaveOne Gold system and obturated with a bioceramic sealer using two techniques: single-cone (Group A, n = 50) and warm vertical compaction (Group B, n = 50). After sealer setting, retreatment procedures were performed using ProTaper Universal Retreatment files combined with passive ultrasonic irrigation. Scanning electron microscopy was used to evaluate smear layer removal and dentinal tubule obstruction. Eighty specimens were subsequently re-obturated with a bioceramic sealer and divided into four subgroups according to the obturation technique used before and after retreatment. A push-out bond strength test was performed on coronal, middle, and apical root sections. Statistical analysis was conducted using SPSS software with a significance level set at p ≤ 0.05. Results: No statistically significant differences were observed between the groups regarding the working time required for root filling removal (p > 0.05). However, significant differences were found in push-out bond strength values among the experimental groups (p < 0.05). Specimens obturated using warm vertical compaction showed significantly higher bond strength compared with the single-cone technique. Scanning electron microscopy observations revealed less residual bioceramic sealer on dentinal walls in the warm vertical compaction group. Conclusions: Within the limitations of this in vitro study, the warm vertical compaction technique demonstrated superior bonding performance and resulted in less residual bioceramic sealer after retreatment compared with the single-cone technique. Full article

Sodium hypochlorite (NaOCl), as the most commonly used irrigant solution, offers strong antibacterial and organic tissue dissolving properties and has the potential to express a strong corrosive effect. The aim of the study was to evaluate the effects of NaOCl on corrosion behavior and cyclic fatigue in five different types of NiTi rotary endodontic instruments. The study examined: ProTaper Universal, ProTaper Next, Twisted File, HyFlex CM, and BioRace, each with 24 samples. Each group was divided into a control subgroup and a subgroup exposed to electrochemical testing of corrosion in 5.25% NaOCl. All instruments were exposed to a cyclic fatigue test in artificial canals with a curvature angle of 60 degrees and radius of 2 mm. The corrosion potential of NaOCl was determined in all groups of instruments. ProTaper Universal had a significantly lower corrosion resistance than ProTaper Next (p < 0.05), Twisted File, BioRace, and HyFlex CM (p < 0.001). HyFlex CM showed significantly higher resistance to cyclic fatigue compared to all the other groups of instruments (p < 0.001). Surface corrosion reduced cyclic fatigue resistance in most of the instrument groups, except in heat-treated instruments with controlled memory. HyFlex CM has proven to have the highest resistance to corrosion and cyclic fatigue. Full article

Background/Objectives: The aim of the present investigation was to validate the diagnostic performance of the AI-based dental cloud software Diagnocat^® AIS (Version 1.0 (UDI: 860010268018), DGNCT LLC, Miami, FL, USA) regarding the detection possibilities of seven different endodontic findings on cone-beam computed tomography (CBCT) against a multi-rater consensus reference standard, and to characterize its calibration, threshold-optimized performance and clinical utility. Methods: 358 root-canal-treated teeth from 167 CBCT scans (167 patients) were retrospectively evaluated at a single private dental practice. From initially included 383 root-canal-treated teeth from 177 patients, 358 (93.5%) were recognized by the AI tool and entered the primary analysis. Two experienced dentists with a clinical focus on endodontics independently graded each tooth and disagreements were adjudicated by a senior expert. Seven different endodontic findings were evaluated: (i) apical (periapical) lesion; (ii) short root-canal filling (apical filling end >2 mm short of the radiographic apex); (iii) voids/lacunae in the root-canal filling; (iv) missed (un-instrumented/un-filled) canal; (v) overfilled root-canal filling (apical extrusion); (vi) apicoectomy (resected root apex with or without retrograde filling); and (vii) coronal restoration with a full-coverage crown. Diagnocat^® output was binarized at the manufacturer-fixed 0.50 probability threshold; sensitivity, specificity, predictive values, accuracy, area under the curve AUC (ROC), Cohen κ and Gwet AC1 were computed with 95% cluster-bootstrap confidence intervals (cluster = scan). Threshold optimization, probability calibration, GEE-based subgroup analyses, and decision-curve analysis were pre-specified. Results: Diagnostic performance varied by finding. AUCs were 0.984 for missed canal, 0.917 for overfilled root canal, 0.902 for short root filling, 0.893 for crown, 0.864 for apical lesion, 0.857 for apicoectomy and 0.761 for voids in the root filling. Apical-lesion sensitivity rose from 33.6% for sub-millimeter lesions to ≥80% for lesion measuring 1–5 mm. Re-tuning the decision threshold raised missed-canal sensitivity from 69.6% to 97.5%. Decision-curve analysis confirmed positive benefits for missed canal and root-filling-quality findings. Conclusions: The AI tool Diagnocat^® can be recommended as a focused screening adjunct in CBCT-based endodontic interpretation for missed canals, crowns, and gross root-filling-quality flaws. Sub-millimeter apical lesions and several less common findings (resorption, instrument fragment, retrograde filling) remain outside the reliable performance envelope of the current platform. Full article

Background: The objective was to synthesize and critically appraise systematic reviews with meta-analysis evaluating the association between irrigation, instrumentation, and obturation procedures and post-operative endodontic pain. Methods: An umbrella review was conducted following PRISMA guidelines. Electronic searches identified systematic reviews published between 2016 and 2025. Eligible studies are systematic reviews that include meta-analyses, published in English and correlating the presence of post-operative pain in 3 different critical stages of root canal treatments, namely irrigation, instrumentation and obturation. Methodological quality was assessed using the AMSTAR 2 tool. Outcomes included pain prevalence and intensity at different time points. Results: Out of 368 records, 25 systematic reviews with meta-analysis met the inclusion criteria: 9 on irrigation, 8 on instrumentation, and 8 on obturation. NaOCl concentrations, irrigant activation, and intracanal cryotherapy were repeatedly reported as being associated with reduced short-term post-operative pain. For instrumentation, most reviews reported lower pain with rotary systems, but two studies found no difference or favored reciprocating kinematics. Apical patency did not appear to increase pain and foraminal enlargement may increase early pain. No clinically consistent differences were observed between bioceramic/calcium silicate-based and resin-based sealers, although calcium silicate sealers seem to support periapical healing. However, the certainty of these findings was limited by heterogeneity, methodological weaknesses, and overlap among primary studies. Methodological limitations were identified across reviews, mainly related to no protocol registration (n = 4), incomplete reporting of excluded studies with justification (n = 11), limited assessment of publication bias, and poor reporting of funding sources for primary studies. Conclusions: Based on current evidence, irrigation, instrumentation, and obturation procedures may influence short-term post-operative pain. However, these findings remain tentative because of heterogeneity, methodological weaknesses, variable review quality, and overlap among primary studies. Further high-quality reviews and clinical trials are needed. Full article

Background/Objectives: Multimodal large language models (LLMs) are increasingly integrated into dental diagnostics. This study evaluated the ability of ChatGPT-4o and Gemini 3 Flash to visually identify endodontic instruments and assess their explanatory plausibility regarding instrument morphology. Methods: Standardized images of five endodontic file systems (Reciproc R25, Reciproc Blue, WaveOne Gold, MM One Shape, and XP-endo Finisher) were submitted to both models via their free tiers. Each image was evaluated 50 times per model (total n = 500) to assess both classification accuracy and response consistency. Visual recognition performance was measured using recall, precision, and F1-score, while the plausibility of morphological explanations was evaluated using a structured 3-point scale. Results: Gemini 3 Flash demonstrated significantly higher recognition performance compared to ChatGPT-4o (p < 0.001). The overall acceptable response rate was higher for Gemini 3 Flash (94.4%, [95% CI: 91.5–97.3%]) than for ChatGPT-4o (67.2%, [95% CI: 61.4–73.0%]; p < 0.001). Notably, Gemini 3 Flash showed strong performance in identifying complex instrument designs, whereas ChatGPT-4o exhibited marked limitations in recognizing certain non-standard geometries. Reliability analysis indicated higher consistency for Gemini 3 Flash (κ = 0.86, [95% CI: 0.81–0.91]) compared to ChatGPT-4o (κ = 0.51, [95% CI: 0.44–0.58]). Conclusions: Gemini 3 Flash outperformed ChatGPT-4o in both classification accuracy and consistency in this controlled visual identification task. While these findings highlight the potential of multimodal LLMs in endodontic workflows, their current performance variability limits direct, autonomous clinical application. Further validation under clinically realistic conditions is required before such systems can be considered reliable adjunctive tools. 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

Apical perforation is a possible complication during root canal treatment, often caused by instrumentation beyond the working length, and requires prompt, precise sealing. In immature teeth needing endodontic therapy, the same principles used for managing apical perforations apply. Despite the widespread use of calcium silicate cement (CSC)-based materials, there is limited evidence comparing the sealing performance of putty-type CSCs and injectable bioceramic sealers in apical perforations under standardized laboratory conditions. This study aimed to compare the sealing ability of Retro-MTA cement and Endoseal MTA sealer in standardized apical perforations using the fluid-filtration method. In this in vitro study, 34 extracted human maxillary central incisors were used and divided into two groups. In Group 1, apical perforations were sealed with Retro-MTA and obturated using warm vertical compaction. In Group 2, perforations were sealed with Endoseal MTA and obturated using the single-cone technique. Micro-leakage was assessed using the fluid-filtration method. Data were analyzed with an independent t-test (α = 0.05). All samples exhibited leakage after two weeks. However, Retro-MTA demonstrated significantly lower micro-leakage than Endoseal MTA (0.265 vs. 0.473 μL/min/cmH₂O; p < 0.001), corresponding to approximately a 44% difference in leakage values between the two materials. The findings indicate that Retro-MTA provides a superior apical seal and lower leakage rates than Endoseal MTA. Therefore, Retro-MTA appears to be the more effective material for sealing apical perforations and managing open apices, potentially providing more stable apical seal under controlled laboratory conditions. Full article

The purpose of this investigation was to establish a clinical diagnosis of the cause of instrument fracture and to evaluate its impact on fragment removal success. One hundred cases of fractured endodontic instruments were analyzed to determine the relationship between fracture cause (flexion, torsion, or combined) and removal outcomes. A diagnostic protocol was developed to classify the fracture mechanism based on radiographic findings, clinical observations, and instrument-related parameters. Fragment length, intracanal location, and removal time were recorded. Torsion was the most frequent cause (54%), followed by combined fracture (33%) and flexion (13%). Flexion-related fragments were significantly longer, located in more accessible areas, and exhibited lower mechanical retention, resulting in shorter removal times (mean: 19.62 min). In contrast, torsion-related fragments were shorter, showed greater retention, and required longer removal times (mean: 32.98 min). Statistical analysis demonstrated a significant association between fracture cause, fragment location, and removal time. The fracture mechanism may serve as a predictive clinical factor for fragment removal difficulty. Early identification of this parameter can improve treatment planning and optimize clinical resource management. Full article

Introduction: Advancements in thermo-mechanical surface treatment of endodontic nickel–titanium (NiTi) instruments introduced another aspect of variation. Particularly related to their metallurgy, which influences their behaviour in relation to temperature. This is clinically significant, considering the variation in the temperatures inside the root canal during instrumentation. This study aimed to compare the effects of different temperatures on the bending stiffness, cyclic fatigue resistance, and cutting efficiency of two reciprocating heat-treated NiTi files: R-Motion (RM) and WaveOne Gold (WOG). Methodology: Bending stiffness was examined in a temperature-controlled water bath, measuring the maximum force in Newtons during a 3 mm tip horizontal displacement. The cyclic fatigue resistance was tested in a simulated stainless-steel canal (35° curvature, 6 mm radius) in dynamic mode at 22 °C, 37 °C, and 45 °C. Time to fracture (TTF) and length of fractured fragment were recorded, and representative samples were examined using scanning electron microscopy. The cutting efficiency was assessed using bovine bone slabs measuring 1.5 mm in thickness and 15 mm in width. The files were activated in reciprocation mode for three minutes while resting on the upper surface of the slab, while submerged in a water bath maintained at 22 °C, 37 °C, or 45 °C. The maximum cutting depth was measured in millimetres under magnification. Additionally, Differential Scanning Calorimetry (DSC) analysis was performed for three specimens of each file type. Results: RM exhibited significantly higher TTF, longer fractured fragments, and smaller cutting depths than WOG across all temperatures. The RM was significantly stiffer at 37 °C and 45 °C only. For each file type, increasing the temperature was associated with a significant increase in stiffness (p < 0.01), except for WOG between 22 °C and 37 °C (p = 0.199). The TTF was significantly higher in RM at 22 °C, while the TTF in WOG increased significantly with lower temperatures. No effect was observed on the length of the fractured fragment. Lower temperatures were also associated with reduced cutting efficiency in both files. Conclusions: Temperature has a significant impact on the properties and performance of RM and WOG and should be considered during instrumentation. File design has a greater influence on their strength and cutting ability than their transformation behaviour related to heat treatment. Full article

Calcium silicate-based sealers are widely used in contemporary endodontics, but their strong interaction with dentinal substrates may complicate their removal during nonsurgical retreatment and potentially hinder canal disinfection. This ex vivo study evaluated the effectiveness of different irrigation activation techniques in removing a calcium silicate-based sealer from oval-shaped root canals. Sixty extracted single-rooted teeth were instrumented and obturated using the single-cone technique with NeoSealer Flo, followed by retreatment using a reciprocating system. Specimens were randomly assigned to four final irrigation protocols: conventional needle irrigation (CNI) with NaOCl/EDTA, ultrasonic activation (US), diode laser activation (LI), and Er:YAG laser activation using the SWEEPS mode (SW) (n = 15). Residual filling material was quantified before and after final irrigation using stereomicroscopic imaging and ImageJ (version 1.54) analysis. Dentinal surface morphology and residual sealer were further evaluated using SEM–EDS. Statistical analysis included one-way ANOVA and chi-square tests (p < 0.05). All protocols significantly reduced residual filling material compared with mechanical retreatment alone (US 15.08%, CNI 7.89%, LI 8.01%, SW 7.20%) (p < 0.01). US resulted in significantly greater sealer removal compared with CNI, LI, and SW, with mean differences ranging from 7.08% to 7.88% (p < 0.05). These findings indicate that irrigation activation enhances the removal of NeoSealer Flo calcium silicate-based sealer, with ultrasonic activation demonstrating greater effectiveness among the evaluated techniques, under the conditions of this experimental setup. Full article

Background/Objectives: Instrument fracture remains a significant complication in endodontics. This study compared the resistance to cyclic fatigue failure between rotary and reciprocating nickel–titanium file systems, as well as differences related to file size and taper. Methods: Nineteen rotary and reciprocating file types (n = 10 per group) were evaluated in three independent test series, harmonized according to file size and system. Cyclic fatigue testing was conducted using a static model with a stainless-steel artificial canal, with an internal diameter of 0.9 mm, a 75° curvature angle, and a fixed radius for each series. Files were operated using preset programs on the X-Smart Plus, Rooter X3000, and Sendoline Endo torque-controlled motors. Time to fracture was recorded digitally, and the total number of full rotations to failure was calculated. The fractured fragments were examined with scanning electron microscopy and fractographic analysis. The data were analyzed using linear models in Stata version 19, with significance set at p ≤ 0.05. Results: Reciprocating file systems demonstrated greater time-to-fracture fatigue resistance than rotary systems. However, these differences were diminished or, in some cases, eliminated when normalized to the number of complete rotations. Fractographic analysis indicated that fractures predominantly resulted from tensile stress rather than shear forces. Conclusions: Reciprocating kinematics generally enhanced fatigue resistance compared with continuous rotation. The results suggest that fatigue resistance in machine-driven nickel–titanium instruments cannot be predicted by motion type or file design alone but reflects a complex interaction between alloy composition, heat treatment, and cross-sectional geometry. Full article

Background: Successful root canal treatment depends on the synergy between mechanical instrumentation and chemical disinfection. The internal canal geometry, particularly taper configuration, critically influences irrigant flow and penetration. Conventional taper designs tend to displace irrigants coronally, creating stagnation zones and limiting cleaning efficacy. The MEA Inverse Taper^® technique introduces a reversed taper geometry designed to retain irrigant within the canal during shaping, forming a fluid reservoir termed the Radicular Tank (RT). This proof-of-concept study aimed to experimentally demonstrate the formation of the RT generated by the MEA Inverse Taper^® design and to compare its qualitative hydrodynamic and shaping behavior with a conventional rotary system (MTWO). Methods: Standardized transparent canal models were instrumented using either the MEA Inverse Taper^® or MTWO sequence. A 1% methylene blue dye served as a visual tracer to assess potential intracanal retention at successive shaping stages. Standardized photographic documentation and digital image superimposition were used to evaluate residual dye retention, canal morphology, and taper variation. Results: The MEA Inverse Taper^® sequence maintained residual dye in the coronal and middle thirds, confirming the formation of the RT. Compared with MTWO, it produced a more conservative taper, minimized coronal and apical displacement of dye, and preserved canal curvature, removing less coronal dentin. Conclusion: The MEA Inverse Taper^® technique creates a qualitative dye-retention phenomenon (Radicular Tank) that allows continuous instrumentation within a visually persistent dye environment. This novel concept may support disinfection efficiency, alongside preserving dentin structure and reducing mechanical stress on rotary instruments, representing a potential advancement in endodontic shaping and irrigation protocols. Full article