This study evaluated the effect of ProTaper Next (PTN), ProTaper Universal Retreatment (PTR) and hybrid instrumentation (HI) for canal filling removal on the fracture resistance (FR), mode of failure (MoF), and filling removal time.

Ninety-six, mandibular premolars were decoronated and randomly divided into 6 groups (n = 16), as follows: sound (S), untreated canals; prepared teeth (P), canals only prepared to ProTaper Universal finishing instrument (F4); endodontically-treated (ET), prepared and obturated canals using the single-cone technique; and groups PTN, PTR, and HI where filling was removed using PTN, PTR, or HI respectively. FR under vertical loading; MoF and time were assessed. Data were analyzed (Significance level [α] = 0.05).

There was a significant difference in FR among all groups (p < 0.001) (HI < P < PTN < S < ET < PTR). HI showed lower FR than S, ET and PTR, and P showed lower FR than PTR (p < 0.05). For experimental groups, there was a significant difference between every group pair (p < 0.05) No significant difference was found regarding MoF distribution (p > 0.05). HI required the highest filling removal time, while PTR required the least (p < 0.05 between every group pair).

The effect of filling removal on FR may depend on the filling removal technique/system used. PTR could be faster and protect against fracture followed by PTN; HI could adversely affect FR. FR may be associated with filling removal time.

This study aimed to assess the impact of a glide-path on the shaping ability of 2 single-file instruments and to compare the centering ability, maintenance of original canal curvatures and area of instrumentation in simulated S-shaped root canals.

Forty simulated S-shaped root canals were used and were prepared with One Curve (group OC), One G and OC (group GOC), Reciproc Blue (group RB) and R-Pilot and RB (group PRB) and scanned before and after instrumentation. The images were analyzed using AutoCAD. After superimposing the samples, 4 levels (D1, D2, D3, and D4) and 2 angles (Δ1 and Δ2) were established to evaluate the centering ability and modification of the canal curvatures. Then, the area of instrumentation (ΔA) was measured. The data were analyzed using 2-way analysis of variance and Tukey's test for multiple comparisons (p < 0.05).

Regarding the centering ability in the apical part (D3, D4), the use of the glide-path yielded better results than the single-file groups. Among the groups at D4, OC showed the worst results (p < 0.05). The OC system removed less material (ΔA) than the RB system, and for Δ1, OC yielded a worse result than RB (p < 0.05).

The glide-path improved the centering ability in the apical part of the simulated S-shaped canals. The RB system showed a better centering ability in the apical part and major respect of the canal curvatures compared with OC system.

This study aimed to evaluate the effectiveness of final irrigation with cold saline solution after endodontic treatment compared with saline solution at room temperature against postoperative pain following endodontic treatment.

A broad search was performed in the PubMed, Web of Science, Scopus, Cochrane Library, Virtual Health Library (LILACS), and Grey Literature databases. Two independent reviewers performed data extraction, risk of bias using the Cochrane methodology, and certainty of evidence using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach.

Eight studies were included in qualitative synthesis. Intracanal cryotherapy favored the reduction of postoperative pain in the systematic review. Four studies were included in meta-analyses. The meta-analysis showed that intracanal cryotherapy reduced postoperative pain in teeth with symptomatic apical periodontitis (SAP) at 24 hours. There was no association between intracanal cryotherapy and control (room temperature) groups in teeth with normal periapical tissue with respect to postoperative pain at 24 hours and 48 hours.

Intracanal cryotherapy was effective in reducing postoperative pain after endodontic treatment in teeth with SAP.

This study evaluated 2 nickel-titanium rotary systems and a complementary protocol with an ultrasonic tip and a small-diameter instrument in flattened root canals.

Thirty-two human maxillary second premolars with flattened canals (buccolingual diameter ≥4 times larger than the mesiodistal diameter) at 9 mm from the radiographic apex were selected. The root canals were prepared by ProDesign Logic (PDL) 30/0.01 and 30/0.05 or Hyflex EDM (HEDM) 10/0.05 and 25/0.08 (n = 16), followed by application of the Flatsonic ultrasonic tip in the cervical and middle thirds and a PDL 25/0.03 file in the apical third (FPDL). The teeth were scanned using micro-computed tomography before and after the procedures. The percentage of volume increase, debris, and uninstrumented surface area were analyzed using the Kruskal-Wallis, Dunn, Wilcoxon, analysis of variance/Tukey, and paired and unpaired t-tests (α = 0.05).

No significant difference was found in the volume increase and uninstrumented surface area between PDL and HEDM (p > 0.05). PDL had a higher percentage of debris than HEDM in the middle and apical thirds (p < 0.05). The FPDL protocol resulted in less debris and uninstrumented surface area for PDL and HEDM (p < 0.05). This protocol, with HEDM, reduced debris in the middle and apical thirds and uninstrumented surface area in the apical third (p < 0.05).

High percentages of debris and uninstrumented surface area were observed after preparation of flattened root canals. The HEDM, Flatsonic tip, and 25/0.03 instrument protocol enhanced cleaning in flattened root canals.

The aim of this study was to evaluate the shaping ability of the TruShape and Reciproc Blue systems and the apical extrusion of debris after root canal instrumentation. The ProTaper Universal system was used as a reference for comparison.

Thirty-three mandibular premolars with a single canal were scanned using micro-computed tomography and were matched into 3 groups (n = 11) according to the instrumentation system: TruShape, Reciproc Blue and ProTaper Universal. The teeth were accessed and mounted in an apparatus with agarose gel, which simulated apical resistance provided by the periapical tissue and enabled the collection of apically extruded debris. During root canal preparation, 2.5% sodium hypochlorite was used as an irrigant. The samples were scanned again after instrumentation. The percentage of unprepared area, removed dentin, and volume of apically extruded debris were analyzed. The data were analyzed using 1-way analysis of variance and the Tukey test for multiple comparisons at a 5% significance level.

No significant differences in the percentage of unprepared area were observed among the systems (p > 0.05). ProTaper Universal presented a higher percentage of dentin removal than the TruShape and Reciproc Blue systems (p < 0.05). The systems produced similar volumes of apically extruded debris (p > 0.05).

All systems caused apically extruded debris, without any significant differences among them. TruShape, Reciproc Blue, and ProTaper Universal presented similar percentages of unprepared area after root canal instrumentation; however, ProTaper Universal was associated with higher dentin removal than the other systems.

The reliability and educational quality of videos on YouTube for patients seeking information regarding instrument separation in root canal treatment were evaluated.

YouTube was searched for videos on instrument separation in root canal treatment. Video content was scored based on reliability in terms of 3 categories (etiology, procedure, and prognosis) and based on video flow, quality, and educational usefulness using the Global Quality Score (GQS). Descriptive statistics were obtained and the data were analyzed using analysis of variance and the Kruskal-Wallis test.

The highest mean completeness scores were obtained for videos published by dentists or specialists (1.48 ± 1.06). There was no statistically significant difference among sources of upload in terms of content completeness. The highest mean GQS was found for videos published by dentists or specialists (1.82 ± 0.96), although there was no statistically significant correlation between GQS and the source of upload.

Videos on YouTube have incomplete and low-quality content for patients who are concerned about instrument separation during endodontic treatment, or who experience this complication during endodontic treatment.

This micro-computed tomographic (CT) study aimed to compare the shaping abilities of ProTaper Next (PTN), One Shape (OS), and One Curve (OC) files in 3-dimensionally (3D)-printed mandibular molars.

In order to ensure standardization, 3D-printed mandibular molars with a consistent mesiobuccal canal curvature (45°) were used in the present study (n = 18). Specimens were instrumented with the OC, OS, or PTN files. The teeth were scanned pre- and post-instrumentation using micro-CT to detect changes of the canal volume and surface area, as well as to quantify transportation of the canals after instrumentation. Two-way analysis of variance was used for statistical comparisons.

No statistically significant differences were found between the OC and OS groups in the changes of the canal volume and surface area before and after instrumentation (p > 0.05). The OC files showed significantly less transportation than the OS or PTN systems for the apical section (p < 0.05). In a comparison of the systems, similar values were found at the coronal and middle levels, without any significant differences (p > 0.05).

These 3 instrumentation systems showed similar shaping abilities, although the OC file achieved a lesser extent of transportation in the apical zone than the OS and PTN files. All 3 file systems were confirmed to be safe for use in mandibular mesial canals.

The purpose of this research was to identify the top 10 most-cited articles on the management of fractured or broken instruments and to perform a bibliometric analysis thereof.

Published articles related to fractured instruments were screened from online databases, such as Web of Science, Scopus, PubMed, and ScienceDirect, and highly cited papers, with at least 50 citations since publication, were identified. The most-cited articles were selected and analysed with regard to publication title, authorship, the journal of publication, year, institution, country of origin, article type, and number of citations.

The top 10 most-cited articles were from various journals. Most were published in the Journal of Endodontics, followed by the International Endodontic Journal, and Dental Traumatology. The leading countries were Australia, Israel, Switzerland, the USA, and Germany, and the leading institution was the University of Melbourne. The majority of articles among the top 10 articles were clinical research studies (n = 8), followed by a basic research article and a non-systematic review article.

This bibliometric analysis revealed interesting information about scientific progress in endodontics regarding fractured instruments. Overall, clinical research studies and basic research articles published in high-impact endodontic journals had the highest citation rates.

To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR), Mtwo-R, ProTaper Next (PTN), and Twisted File Adaptive (TFA) systems.

The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the negative control group. One hundred teeth were prepared, obturated, and then divided into 5 retreatment groups. The retreatment procedures were performed using the following files: PTR, Mtwo-R, PTN, TFA, and hand files. After filling material removal, apical enlargement was done using apical size 0.50 mm ProTaper Universal (PTU), Mtwo, PTN, TFA, and hand files. Digital images of the apical root surfaces were recorded before preparation, after preparation, after obturation, after filling removal, and after apical enlargement using a stereomicroscope. The images were then inspected for the presence of new apical cracks and crack propagation. Data were analyzed with χ² tests using SPSS 21.0 software.

New cracks and crack propagation occurred in all the experimental groups during the retreatment process. Nickel-titanium rotary file systems caused significantly more apical crack formation and propagation than the hand files. The PTU system caused significantly more apical cracks than the other groups after the apical enlargement stage.

This study showed that retreatment procedures and apical enlargement after the use of retreatment files can cause crack formation and propagation in apical dentin.

To determine the optimal timing for post space preparation of root canals sealed with epoxy resin-based AH Plus sealer in terms of its polymerization and influence on apical leakage.

The epoxy polymerization of AH Plus (Dentsply DeTrey) as a function of time after mixing (8, 24, and 72 hours, and 1 week) was evaluated using Fourier transform infrared (FTIR) spectroscopy and microhardness measurements. The change in the glass transition temperature (T_g) of the material with time was also investigated using differential scanning calorimetry (DSC). Fifty extracted human single-rooted premolars were filled with gutta-percha and AH Plus, and randomly separated into five groups (n = 10) based on post space preparation timing (immediately after root canal obturation and 8, 24, and 72 hours, and 1 week after root canal obturation). The extent of apical leakage (mm) of the five groups was compared using a dye leakage test. Each dataset was statistically analyzed by one-way analysis of variance and Tukey's post hoc test (α = 0.05).

Continuous epoxy polymerization of the material with time was observed. Although the T_g values of the material gradually increased with time, the specimens presented no clear T_g value at 1 week after mixing. When the post space was prepared 1 week after root canal obturation, the leakage was significantly higher than in the other groups (p < 0.05), among which there was no significant difference in leakage.

Poor apical seal was detected when post space preparation was delayed until 1 week after root canal obturation.