Biological response to endodontic treatment in one versus two-visit: a systematic review and meta-analysis of animal studies.

OBJECTIVES: To perform a systematic review of animal studies that compared the histopathological characteristics between teeth with apical periodontitis after endodontic treatment in one or two visits. MATERIALS AND METHODS: This systematic review was registered on the International Prospective Register of Systematic Reviews (PROSPERO) - CRD42022340849. Studies were collected from PubMed/MEDLINE, LILACS, EMBASE, Livivo, SciELO, Web of Science, Scopus, and Cochrane Library and manual and gray literature searches. Animal studies that evaluated histological characteristics after endodontic treatment of teeth with apical periodontitis in one or two visits were included. Risk of bias analysis of the included studies was performed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) tool. Data synthesis of the included studies with quantitative data was performed, and meta-analysis was conducted with the Comprehensive Meta-Analysis software, using the random effects model and odds ratio (OR). RESULTS: Eighteen studies met the inclusion criteria (Kappa = 0.891). Meta-analyses indicated values in inflammatory infiltrate intensity with effect size of 5.5% (95% CI: 0.020-0.148; p < 0.001), periodontal ligament thickness: 25.6% (95% CI: 0.134-0.487; p < 0.001), dentin resorption: 13% (95% CI: 0.015-1.141; p = 0.066), cementum resorption: 7.1% (95% CI: 0.015-0.325; p = 0.001), bone resorption: 1.4% (95% CI: 0.002-0.130; p < 0.001), mineralized tissue resorption: 42.8% (95% CI: 0.110-1.671; p = 0.222), biological apical sealing: 13.1% (95% CI: 0.055-0.314; p < 0.001), and presence of microorganisms: 10.3% (95% CI: 0.014-0.747; p = 0.025). CONCLUSIONS: When considering animal studies, the two-visit endodontic treatment, using calcium hydroxide-based intracanal medication, resulted in better biological repair characteristics. CLINICAL RELEVANCE: A two-visit endodontic treatment with calcium hydroxide-based intracanal medication yields superior histopathological outcomes.

Referred pain is associated with greater odontogenic spontaneous pain and a heightened pain sensitivity in patients with symptomatic irreversible pulpitis.

BACKGROUND: Symptomatic irreversible pulpitis often results in heightened reactions to thermal stimuli such as pain evoked by a cold stimulus, and spontaneous odontogenic pain (unprovoked pain). OBJECTIVE: This study primarily compared the clinical manifestations of odontogenic spontaneous pain and pain provoked by cold stimulus specifically focusing on their sensory discriminative characteristics (intensity, duration and quality) between symptomatic irreversible pulpitis patients with and without referred pain. METHODS: Twenty-three patients with symptomatic irreversible pulpitis with referred pain and 12 patients without referred pain were included in this cross-sectional study. The following outcomes were assessed: odontogenic spontaneous pain and its descriptors; pain evoked by cold stimulus and qualitative sensory testing before and after local anaesthesia; referred pain location; use of analgesic medication; complementary anaesthesia efficacy. T-test, chi-squared and McNemar tests were applied to the data (p < .50). RESULTS: Patients with referred pain presented a greater odontogenic pain intensity (p < .05) when considered the average of the last 24 h. These patients also showed higher pain rating and pain descriptors (p < .05). Intensity and duration of the pain evoked by cold stimulus in the non-affected contralateral tooth at baseline were higher for patients with referred pain (p < .05). CONCLUSION: Symptomatic irreversible pulpitis patients with referred pain present greater odontogenic spontaneous pain and a heightened pain sensitivity. Therefore, patients with referred pain seem more complex from a pain severity perspective, supporting the clinical utility of discriminating symptomatic irreversible pulpitis with and without referred pain.

Publication trends of the Journal of Esthetic and Restorative Dentistry: A bibliometric analysis.

OBJECTIVE: The Journal of Esthetic and Restorative Dentistry (JERD) stands out as one of the most prominent international journals publishing research in esthetic dentistry. This study analyzed articles published by JERD since the year 2000 through bibliometric analysis. METHODOLOGY: The search was conducted in January 2024 using Scopus. The following data were extracted from the articles: citation count, year, language, access type, funding agency, study design, theme (general and specific), country, institution, authors, and keywords. The VOSviewer software was used to generate collaborative network maps among the data. Dimensions were consulted to measure altmetric data. Google Trends was used to investigate the global popularity of JERD research. RESULTS: A total of 1394 articles were included in this analysis. Citation count ranged from 0 to 625 (average: 16.9). Articles were published between 2000 and 2023. Laboratory studies were more prevalent (n = 850), with the most investigated general theme being restorative procedures (n = 882), and the highlighted specific theme being the use of composite resin (n = 327). The United States had the highest number of articles (n = 640), with the diverse distribution among other countries. The most common keyword was "cad/cam" (n = 63). VOSviewer demonstrated high collaboration among countries. Intense mentions were identified primarily on Facebook. According to Google Trends, Egypt was the country that searched for JERD the most. CONCLUSIONS: JERD exhibited significant growth in the number of published articles and their diversity by topics, types, origin (country), number of citations, and impact factor. CLINICAL SIGNIFICANCE: The JERD is a journal that publishes studies influencing clinical practice. Identifying the key characteristics of this journal is essential for charting future paths.

Effectiveness of a new endodontic irrigation system for removing smear layer and dissolving simulated organic matter.

OBJECTIVES: The study aimed to evaluate the potential for the dissolution of organic tissue in areas of simulated complexity and cleaning of root canal walls of the new iVac® endodontic irrigation system. MATERIAL AND METHODS: Thirty mandibular premolars were evaluated by scanning electron microscopy before and after biomechanical preparation. Then, they were distributed according to the final irrigation protocol into groups with conventional irrigation, ultrasonic agitation with metallic insert (UA), and iVac® system, and new photomicrographs were obtained. For tissue dissolution analysis, glass capillaries filled with catgut were attached to the cervical and apical thirds of twenty-one prototyped upper incisors. They were weighed before and after the previously mentioned irrigation protocols. The data were statistically compared with a significance level of 5%. RESULTS: The final irrigation provided greater cleaning of the root canal walls in the cervical, middle, and apical thirds of the root canals (P < 0.05), with no statistically significant difference between UA and iVac®, regardless of the analyzed thirds. Both ultrasonic irrigation protocols dissolved a significantly greater volume than the conventional irrigation protocol (P < 0.05), with no difference between the two protocols (P < 0.05). CONCLUSIONS: The iVac® system showed root canal wall cleaning and tissue dissolution similar to UA with a metallic insert, and both were superior to conventional irrigation. CLINICAL RELEVANCE: The new irrigation system iVac is more effective than conventional irrigation and has similar root canal wall cleaning and tissue dissolution to UA.

Influence of conservative endodontic access cavities on instrumentation of oval-shaped straight root canals.

AIM: To evaluate the influence of the design of endodontic access cavities on the percentage of unprepared areas of canal walls and flexural fatigue of instruments activated by reciprocating movement in oval-shaped straight root canals of extracted teeth. METHODOLOGY: Forty-two mandibular incisors with oval canals were scanned by a microcomputed tomography (micro-CT) device for homogeneous selection and distribution of the samples. Then, the teeth were divided into two groups (n = 21) according to the design of access cavity being tested: ultraconservative endodontic access cavity (UltraAC) and traditional access cavity. The canals were accessed with the aid of a surgical microscope, instrumented with the WaveOne Gold Medium system and irrigated with 2.5% NaOCl and 17% EDTA. The unprepared areas of the canal wall were analysed by overlaying images before and after instrumentation and expressed as percentages. micro-CT data were analysed using t-test, Mann-Whitney and Wilcoxon tests. The endodontic instruments used during instrumentation were subjected to static flexural fatigue testing using an artificial stainless steel canal with a 60° angle of curvature and a radius of 5 mm, located 5 mm from the tip of the instrument. The instruments were activated until fracture occurred, and the time in seconds for the fracture was recorded using a digital timer. The number of cycles to fracture was calculated and analysed statistically. For flexural fatigue data, an anova test complemented by a Tukey range test was used. The significance level of 5% was used for all analyses. RESULTS: There was no significant difference between the groups related to unprepared areas by the instrument during canal preparation (p > .05). The difference in flexural fatigue resistance between the groups was not significant. CONCLUSION: The use of UltraAC did not interfere with the canal instrumentation of extracted mandibular incisors with straight and oval canals. There was no difference in the flexural fatigue resistance of the instruments in relation to access cavity design.

Effect of obturation technique on penetration of calcium silicate-based sealer into dentinal tubules after endodontic retreatment of mandibular premolars.

OBJECTIVE: Confocal laser scanning microscopy (CLSM) was used to investigate the penetration of endodontic sealers into the dentinal tubules after retreatment using two different obturation techniques. MATERIALS AND METHODS: Thirty mandibular premolars were prepared up to instrument F3 (ProTaper Universal, Dentsply) and filled with Endofill using the single cone technique. The canals were retreated using Mtwo instruments. Reobturation was performed with the Bio-C sealer mixed with a fluorophore dye (Fluo-3) using either the lateral condensation technique (group LC) or the single cone technique (group SC) (n = 15). Teeth were sectioned 2, 4, and 6 mm from the apex and analyzed with CLSM to assess the penetration of the sealer into the canal perimeter and the maximum depth of penetration of the sealer into the dentinal tubules. Data were analyzed using ANOVA and the Student-t and Holm-Sidak tests. RESULTS: In the apical segment, the penetrated perimeter was significantly higher in the LC group than in the SC group (p < 0.05); no significant difference was found in the middle and cervical segments (p > 0.05). In terms of penetration depth, no significant differences were found for any of the segments studied (p > 0.05). CONCLUSION: The LC technique promoted a higher percentage of canal circumference penetrated by the sealer than the SC technique in the apical segment after endodontic retreatment. CLINICAL RELEVANCE: CLSM demonstrated that the LC technique promoted a higher percentage of canal perimeter penetrated by the Bio-C sealer than the SC technique in the apical segment of mandibular premolars after retreatment.

Evaluation of foramen locating accuracy of an endodontic motor integrated with electronic foramen employing optimal glide path kinematics.

OBJECTIVE: This study aimed to evaluate the accuracy of the auto apical function in the maintenance of the apical limit of instrumentation during glide path procedures when associated to OGP kinematics of Tri Auto ZX2, compared to the continuous rotation of the same motor, as well as Root ZX II and VDW Gold. MATERIALS AND METHODS: Forty-eight extracted human mandibular single-rooted premolars were selected. After endodontic access, cervical pre-flaring was performed using size 30, 0.10 taper rotary instruments, and the apical foramen size was standardized to 200 µm. Teeth were randomly divided into four groups (n = 12) according to the device and kinematics. For all the groups, the Auto Apical Stop function (AAS) was set to the 0.0 mark. Glide path instruments size 25, .01 taper were activated inside the canals until the apical limit was reached. Then, the files were fixed with cyanoacrylate to the teeth and decoupled from the equipment. Data were statistically analyzed in GraphPad Prism 6.0 software with the significance set at 5% (Kruskal-Wallis tests). RESULTS: There was no difference in the mean deviation between the groups. No significant difference was found among the groups when the distributions and percentages of differences between the file tip and the apical foramen were compared (P > 0.05). CONCLUSION: The use of auto apical function at the 0.0 mark of all tested devices provided an adequate control of the apical limit during glide path preparation. Foramen locating accuracy of Tri Auto ZX2 in OGP kinematics was similar to those of Tri Auto ZX2, Root ZX II, and VDW Gold in continuous kinematics. CLINICAL RELEVANCE: Clinical strategies in canal negotiation and glide path as OGP motion associated to electronic foramen locators could reduce iatrogenic risk of deviation and file fractures and create an easier initial preparation to facilitate endodontic procedures.

Effect of association of non-steroidal anti-inflammatory and antibiotic agents with calcium hydroxide pastes on their cytotoxicity and biocompatibility.

OBJECTIVES: Evaluate the cytotoxicity and biocompatibility of calcium hydroxide paste [Ca (OH)2] associated with 5% diclofenac sodium, ibuprofen, or amoxicillin. MATERIALS AND METHODS: Pre-osteoblast-like cells were cultivated and the MTT test was used to determine the cytotoxicity of the paste extracts after time intervals of 24, 48, 72 h, and 7 days. Tubes containing Ca (OH)2 pastes associated with the drugs and empty tubes were implanted in subcutaneous tissue of 30 rats. After 7 and 30 days, the specimens were removed and submitted to histological analysis. The data obtained were submitted to Kruskal-Wallis and Dunn tests (p ≤ 0.05). RESULTS: All the Ca (OH)2 pastes promoted cell viability after all periods. At 7 days, there was greater inflammatory tissue reaction adjacent to the implants. At 30 days, there was a significant reduction in the number of inflammatory cells, and increase in fibroblasts in all groups. In this period, a lower number of inflammatory cells and a higher number of fibroblasts were observed in the capsules adjacent to the association with diclofenac, when compared with the other mixtures (p ≤ 0.05); the capsule thickness was greater at 7 days than at 30 days. CONCLUSIONS: The Ca (OH)2 pastes associated with the drugs were not cytotoxic and presented biocompatibility after implantation in rat subcutaneous tissues. CLINICAL RELEVANCE: Ca (OH)2 pastes with anti-inflammatory or antibiotic may be clinical alternatives as intracanal medication to reduce resistant microorganisms in root canal system.

Influence of cervical preflaring and root canal preparation on the fracture resistance of endodontically treated teeth.

BACKGROUND: Evaluate the fracture resistance of endodontically treated teeth after cervical preflaring and root canal preparation and to assess the volume of the root canal and the amount of remaining root dentin before and after cervical preflaring. METHODS: Forty-four mandibular incisors were selected using micro-CT scanning and distributed into 4 groups (n = 11) according to the instrument used for cervical preflaring: control group - no cervical preflaring; Gates Glidden - burs size #2 and #3; WXN - 25.07 Navigator instrument; and Easy - 25.08 ProDesign S instrument. Coronal opening was performed, and the canals were prepared with Wave One Gold Primary and filled with an epoxy-resin based sealer and gutta-percha cones. Micro-CT scans were performed before and after root canal instrumentation. All images were reconstructed and assessed for the thickness of mesial and distal root dentin at 3 mm and 5 mm from the cement -enamel junction and for the volume of cervical portion of the canal after preparation. Fracture resistance test was performed applying compressive loads at a crosshead speed of 0.5 mm/min, applied on the palatal aspect of specimens at 135° along the long axis of the tooth. The data were analyzed using ANOVA and Tukey's test (P = .05). RESULTS: Cervical preflaring and canal preparation reduced the dentin thickness (P < .05) and increased the canal volume (P < .05) in all groups at 3 mm an 5 mm. Cervical preflaring with Gates Gliden burs reduced the fracture resistance of endodontically treated teeth (P < .05). CONCLUSIONS: All instruments reduced the dentin thickness and increased the canal volume in the cervical at 3 mm and 5 mm. Gates Glidden reduced fracture resistance of mandibular incisors submitted to cervical preflaring, whereas NiTi instruments did not. CLINICAL RELEVANCE: Cervical preflaring assumes particular importance previously to the root canal preparation because it minimizes the occurrence of operative accidents, and permits more accurate determination of working length and the apical diameter.

Comparison of efficiency of the retreatment procedure between Wave One Gold and Wave One systems by Micro-CT and confocal microscopy: an in vitro study.

INTRODUCTION: To compare, by Micro-CT and confocal laser scanning microscopy (CLSM), the ability of the Wave One Gold and Wave One systems to remove filling material from mesial canals of mandibular molars, effective time spent; quantity of extruded material, and percentage of sealer in the dentinal tubules after retreatment and re-obturation procedures. MATERIALS AND METHODS: Ten first mandibular molars (n = 20 mesial canals) were prepared and filled with gutta-percha and Endofill sealer mixed with Rhodamine B dye using the single cone technique. After 7 days, the canals were scanned using a high-definition micro-computer tomography with 19-mm voxel size and divided into two groups (n = 10) according to the system used in retreatment: group 1, Wave One (WO), and group 2, Wave One Gold (WG). After removing filling material with the primary file of each system, the WO 40/.08 and WG 35/.06 files were used. After using each file, a new scanning was performed and the residual filling material and extruded filling material were measured. The effective time spent to remove the canal filling was measured after each instrument. After retreatment, the teeth were re-obturated with gutta-percha and AH Plus sealer mixed with fluorescein dye using the single-cone technique. The roots were sectioned at 2, 4 and 6 mm and analysed by CLSM to measure the percentage of remaining sealer and the sealer of the new root canal filling. The data were statistically compared (P < 0.05). RESULTS: Both systems presented a similar volume of filling material remaining in the canals after the use of the two instruments, similar residual and new material in the dentinal tubules, and similar extrusion of material (P > 0.05). When using WO 25, the operator spent significantly less effective time than when using WG 25 (P < 0.05); however, use of WG 35 and WO 40 required a similar time to remove filling material from the canals (P > 0.05). CONCLUSIONS: Neither of the two systems removed all the filling material. The WG system presented similar ability in removing filling and extruded material in comparison with WO system. The effective time spent was shorter for WO 25 than for WG 25. CLINICAL RELEVANCE: Wave One Gold can be an alternative to perform retreatment considering that in comparison with Wave One, there was no difference in filling material removal capacity and extruded materials. There was only difference in the effective time spent, in which the operator spent more time with WG 25 than with WO 25.

Effect of temperature on the cyclic fatigue resistance of thermally treated reciprocating instruments.

OBJECTIVES: The aim of this study was to evaluate the impact of body temperature on the cyclic fatigue resistance of different NiTi alloys used for the manufacturing of Reciproc Blue R25 (RB 25.08; VDW, Munich, Germany), X1 Blue File 25 (X1 25.06; MK Life Medical and Dental Products, Porto Alegre, Brazil) and WaveOne Gold Primary (WOG 25.07; Dentsply Maillefer, Ballaigues, Switzerland). MATERIALS AND METHODS: Sixty instruments of the RB 25.08, X1 25.06 and WOG 25.07 systems were used (n = 20). Cyclic fatigue tests were performed at room temperature (20° ± 1 °C) and at body temperature (37° ± 1 °C). The instruments were reciprocated until fracture occurred in an artificial stainless steel canal with a 60° angle and a 5-mm radius of curvature. The time to fracture (TTF) was recorded. Also, the number of cycles to fracture (NCF) was calculated. Data were analysed using one-way ANOVA and Tukey's tests for inter-group comparison at both temperatures and for the reduction of cyclic fatigue at body temperature. For intra-group comparison at the different temperatures, the unpaired t test was used. RESULTS: The cyclic fatigue test at 20 °C showed that RB 25.08 and X1 25.06 presented significantly higher TTF and NCF than WOG 25.07 (P < 0.05). At 37 °C, all groups presented significant reduction of TTF and NCF (P < 0.05). RB 25.08 presented significant higher TTF than WOG 25.07 (P < 0.05). Regarding the NCF, there was no significant difference among the groups (P > 0.05). The WOG 25.07 presented the lowest percentage reduction of cyclic fatigue (P < 0.05). CONCLUSION: The body temperature treatment caused a marked reduction of the cyclic fatigue resistance for all reciprocating instruments tested. The RB 25.08 and X1 25.06 systems presented similar results at both temperatures tested. However, WOG 25.07 presented the lowest percentage reduction in fatigue resistance at body temperature. CLINICAL RELEVANCE: The cyclic fatigue resistance of NiTi reciprocating instruments has been evaluated at room temperature. However, the fatigue resistance significantly decreases upon exposure to body temperature, which could affect the mechanical behaviour of the NiTi instruments during root canal preparation.

Cyclic fatigue and torsional strength of three different thermally treated reciprocating nickel-titanium instruments.

OBJECTIVES: The aim of this study was to evaluate the cyclic and torsional fatigue resistance of the reciprocating single-file systems Reciproc Blue 25.08 (VDW GmbH, Munich, Germany), Prodesign R 25.06 (Easy Dental Equipment, Belo Horizonte, Brazil), and WaveOne Gold 25.07 (Dentsply/Tulsa Dental Specialties, Tulsa, OK, USA). MATERIALS AND METHODS: Sixty reciprocating instruments of the systems Reciproc Blue R25 (RB #25 .08 taper), Prodesign R (PDR #25 .06 taper), and WaveOne Gold (WOG #25 .07 taper) (n = 20) were used. Cyclic fatigue resistance testing was performed by measuring the time to failure in an artificial stainless steel canal with a 60° angle of curvature and a 5-mm radius located 5 mm from the tip (n = 10). The torsional test (ISO 3630-1) evaluated the torque and angle of rotation at failure of new instruments (n = 10) in the portion 3 mm from the tip. The fractured surface of each fragment was also observed using scanning electron microscopy (SEM). In addition, a supplementary examination was performed to measure the cross-sectional area of each instrument 3 and 5 mm from the tip. The data were analyzed using one-way ANOVA and Tukey's test, and the level of significance was set at 5%. RESULTS: The cyclic fatigue resistance values of PDR 25.06 were significantly higher (P < 0.05). RB 25.08 showed higher fatigue resistance than WOG 25.07 (P < 0.05). The torsional test showed that PDR 25.06 had lower torsional strength (P < 0.05). No differences were observed between RB 25.08 and WOG 25.07 (P > 0.05). PDR 25.06 showed higher angular rotation values than RB 25.08 and WOG 25.07 (P < 0.05). RB 25.08 presented higher angular rotation than WOG 25.07 (P < 0.05). The cross-sectional area analysis showed that PDR 25.06 presented the smallest cross-sectional areas at 3 and 5 mm from the tip (P < 0.05). CONCLUSION: PDR 25.06 presented the highest cyclic fatigue resistance and angular rotation until fracture compared to RB 25.08 and WOG 25.07. In addition, RB 25.08 and WOG 25.07 had higher torsional strength than PDR 25.06. CLINICAL RELEVANCE: In endodontic practice, thermally treated reciprocating instruments have been used for the root canal preparation of curved and constricted canals; therefore, these instruments should present high flexibility and suitable torsional strength to minimize the risk of instrument fracture.

Experimental maxillary sinus augmentation using a highly bioactive glass ceramic.

Physicochemical characteristics of a biomaterial directly influence its biological behavior and fate. However, anatomical and physiological particularities of the recipient site also seem to contribute with this process. The present study aimed to evaluate bone healing of maxillary sinus augmentation using a novel bioactive glass ceramic in comparison with a bovine hydroxyapatite. Bilateral sinus augmentation was performed in adult male rabbits, divided into 4 groups according to the biomaterial used: BO-particulate bovine HA Bio-Oss(®) (BO), BO+G-particulate bovine HA + particulate autogenous bone graft (G), BS-particulate glass ceramic (180-212 µm) Biosilicate(®) (BS), and BS+G-particulate glass ceramic + G. After 45 and 90 days, animals were euthanized and the specimens prepared to be analyzed under light and polarized microscopy, immunohistochemistry, scanning electron microscopy (SEM), and micro-computed tomography (µCT). Results revealed different degradation pattern between both biomaterials, despite the association with bone graft. BS caused a more intense chronic inflammation with foreign body reaction, which led to a difficulty in bone formation. Besides this evidence, SEM and µCT confirmed direct contact between newly formed bone and biomaterial, along with osteopontin and osteocalcin immunolabeling. Bone matrix mineralization was late in BS group but became similar to BO at day 90. These results clearly indicate that further studies about Biosilicate(®) are necessary to identify the factors that resulted in an unfavorable healing response when used in maxillary sinus augmentation.

Effect of ultrasonic tip and root-end filling material on bond strength.

OBJECTIVES: The objective of this study was to evaluate the bond strength of three root-end filling materials (MTAA-MTA Angelus, MTAS-experimental MTA Sealer, and ZOE- zinc oxide and eugenol cement) in retrograde preparations performed with different ultrasonic tips (CVD, Trinity, and Satelec). MATERIALS AND METHOD: Ninety 2-mm root sections from single-rooted human teeth were used. The retrograde cavities were prepared by using the ultrasonic tips, coupled to a device for position standardization. The specimens were randomly divided into nine groups: CVD MTAA; CVD MTAS; CVD ZOE; Trinity MTAA; Trinity MTAS; Trinity ZOE; Satelec MTAA; Satelec MTAS; Satelec ZOE. Each resin disc/dentin/root-end filling material was placed in the machine to perform the push-out test. The specimens were examined in a stereomicroscope to evaluate the type of failure. Data were submitted to statistical analysis using ANOVA and Tukey tests (α = 0.05). RESULTS: The highest bond strength was observed for the CVD tip irrespective of the material used (P < 0.05). There was no significant difference for the Trinity TU-18 diamond and S12 Satelec tips (P > 0.05). MTAA and MTAS showed highest bond strength. The most common type of failure was adhesion between the filling material and dentin wall, except for ZOE, where mixed failure was predominant. CONCLUSIONS: The CVD tip favored higher bond strength of the root-end filling materials. MTA Angelus and experimental MTAS presented bond strength to dentin prepared with ultrasonic tips. CLINICAL RELEVANCE: Root-end preparation with the CVD tip positively influences the bond strength of root-end filling materials. MTA Angelus and experimental MTAS present bond strength to be used as root-end filling materials.

Micro-CT Assessment of Filling Removal Effectiveness in the Apical Third of Curved Canals with Different Types of Anatomy.

Introduction: The aim of this study was to assess the effectiveness of filling removal material from the apical third of curved mesial root canals of mandibular molars. Reciprocating instrumentation followed by additional rotary instrumentation with instruments made of alloys with different heat treatments was evaluated. Materials and Methods: Thirty-six mesial roots of mandibular molars were divided into two groups: Group Class IV consisted of 16 roots with two independent canals, and Group Class II consisted of 20 roots with two canals that merged into one at their apical level. Each of these two groups were further divided into two subgroups, according to the additional rotary instrument used after the reciprocating instrumentation: Group RH and Group RM for Hyflex and Mtwo, respectively. After each procedural step, the roots were scanned by micro-tomography. After each step of filling removal, the Wilcoxon matched pair test and the Mann-Whitney test were used for the evaluation between groups. The significance level adopted was 5%. Results: Significant differences were observed between groups with different Class II and Class IV anatomies, regarding filling removal after Reciproc (P<0.05). After the use of an additional rotary instrumentation, no differences were observed between the two groups (P>0.05). Conclusions: In the apical third of mesial roots of mandibular molars with Class II anatomy, an additional rotary instrumentation was shown to be necessary for improving the removal of filling material after using the single-file reciprocating instrumentation technique.

Impact of different agitation methods on smear layer cleaning of mesial canals with accentuated curvature.

Objectives: This study evaluated the impact of different methods of irrigant agitation on smear layer removal in the apical third of curved mesial canals of 3 dimensionally (D) printed mandibular molars. Materials and Methods: Sixty 3D-printed mandibular second molars were used, presenting a 70° curvature and a Vertucci type II configuration in the mesial root. A round cavity was cut 2 mm from the apex using a trephine of 2 mm in diameter, 60 bovine dentin disks were made, and a smear layer was formed. The dentin disks had the adaptation checked in the apical third of the teeth with wax. The dentin disks were evaluated in environmental scanning electron microscope before and after the following irrigant agitation methods: G1(PIK Ultrasonic Tip), G2 (Passive Ultrasonic Irrigation with Irrisonic- PUI), G3 (Easy Clean), G4 (HBW Ultrasonic Tip), G5 (Ultramint X Ultrasonic tip), and G6 (conventional irrigation-CI) (n = 10). All groups were irrigated with 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid. Results: All dentin disks were 100% covered by the smear layer before treatment, and all groups significantly reduced the percentage of the smear layer after treatment. After the irrigation protocols, the Ultra-X group showed the lowest coverage percentage, statistically differing from the conventional, PIK, and HBW groups (p < 0.05). There was no significant difference among Ultramint X, PUI-Irrisonic, and Easy Clean (p > 0.05). None of the agitation methods could remove the smear layer altogether. Conclusions: Ultramint X resulted in the most significant number of completely clean specimens.

Does the mixing method of AH Plus Jet affect its physicochemical and mechanical properties?

INTRODUCTION: The purpose of this study was to evaluate whether the mixing method of AH Plus Jet sealer affects its physicochemical and mechanical properties. METHODS: The properties of AH Plus Jet sealer were analyzed when mixed using either the Auto Mix Tip or manual mixing. The evaluated properties included radiopacity (n=5), initial and final setting times (n=5), flow (n=5), and solubility (n=3), following specifications outlined in ISO 6876/2012 and ADA Nº 57/2000. pH levels were measured at intervals of 3, 24, 72, and 168 hours (n=10). The push-out bond strength test was conducted using a universal testing machine and using bovine teeth (n=30). Failure modes were analyzed with stereomicroscopy. Porosity was evaluated under micro-CT (n=5) and scanning electron microscopy was also performed (n=5). One-way analysis of variance and Tukey, unpaired t-tests, or Mann-Whitney tests were used with a significance level of 5%. RESULTS: The Auto Mix exhibited a radiopacity value of 12.11 mmAl, whereas manual mixing resulted in 12.55 mmAl (P>0.05). For initial and final setting times, Auto Mix showed 901 minutes and 1779 minutes, respectively, while manual mixing recorded values of 631 minutes and 1504 minutes (P<0.05). In terms of flow, Auto Mix demonstrated higher values (25.26 mm) than manual mixing (21.71 mm) (P<0.05). No statistical differences were observed between the two methods for solubility and pH (P>0.05). Manual mixing presented a higher bond strength value (14.52 MPa) than Auto Mix (9.81 MPa) (P<0.05). The mixed failure mode was the most frequent outcome for both methods. The highest porosity was observed for Auto Mix (P<0.05). Scanning electron microscopy analysis revealed that manual mixing resulted in a smoother surface with fewer pores and smaller, more evenly distributed agglomerates compared to automatic mixing. CONCLUSION: The mixing method employed for AH Plus Jet sealer influences some physicochemical and mechanical properties of the material.

Biaxial flexural strength of hydrothermally aged resin-based materials.

PURPOSE: The strength of temporary restorations plays a vital role in full-mouth reconstruction, and it can be impacted by the aging process. The aim of this in vitro study was to evaluate the biaxial flexural strength and fractographic features of different resin-based materials submitted to thermal aging. MATERIAL AND METHODS: One hundred and ninety-two resin disc-shaped specimens (6.5 mm in diameter and 0.5 mm in thickness) were fabricated and divided into six experimental groups according to the resin-based materials (Filtek Bulk-Fill flowable resin; J-Temp temporary resin; and Fuji Lining glass ionomer cement) and aging process (before and after thermal cycling). Biaxial flexural strength test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min before and after thermal cycling (5 °C and 55 °C, 5760 cycles, 30 s). The mechanical properties were assessed using Weibull parameters (characteristic strength and Weibull modulus) (n = 30). Fractured specimens were examined under a polarized light stereomicroscope to identify crack origin and propagation direction. The surface microstructure of the resin-based materials was assessed by scanning electron microscopy (n = 2). The Weibull modulus (m), characteristic strength, and reliability properties were calculated, and a contour plot was used to detect differences among groups (95% confidence interval). RESULTS: The Weibull modulus (m), characteristic strength, and reliability of the resin-based compounds were influenced by material type and thermal aging (p < 0.05). Weibull modulus (m) revealed no differences when comparing the materials and aging process (p > 0.05), except for the preceding aging period where Filtek Bulk-Fill exhibited higher values compared to J-Temp (p < 0.05). Filtek Bulk-Fill demonstrated superior characteristic strength and reliability compared to J-Temp and Fuji Lining before and after thermal cycling (p < 0.05). Fractography of the resin-based materials showed fractures originating from surface defects exposed to tensile side and their propagation toward the compressive side. Generally, no differences in surface microstructure were observed on micrographs before and after thermal aging for Filtek Bulk-Fill and Fuji Lining. However, the aging process developed flaws in J-Temp. CONCLUSION: Resin-based material composition resulted in different flexural strength performance, impacting the Weibull modulus (m), characteristic strength, and reliability of the resin-based restorations.

A Global Overview of Guided Endodontics: A Bibliometric Analysis.

INTRODUCTION: This review aimed to analyze the trend and main characteristics of articles related to guided endodontics (GE). METHODS: The search was conducted in May 2023 on Web of Science. GE-related articles were included, and conferences were excluded. Three researchers selected the articles and extracted: the number of citations; year and journal; design and study theme; authorship and institutions; country and continent. Collaborative networks were generated in the Visualization of Similarities Viewer software. The relationship between data was determined by Spearman's correlation. Google Trends was used to investigate the global popularity of GE research. RESULTS: The search resulted in 135 articles, of which 85 were included. The most cited article totaled 116 citations. The studies were published between 2016 and 2023, most frequently in 2022 (n = 22). The most prevalent journal was the Journal of Endodontics (n = 28). Case report (n = 38) was the most frequent study design. The most studied theme was the use of static GE for calcified canals (n = 27). Connert T was the author with the highest number of articles (n = 13). The University of Basel (n = 9) stood out. The most prevalent country was Brazil (n = 13). Europe was the most frequent continent (n = 38). Visualization of Similarities Viewer demonstrated an interaction between authors. There was a moderate positive correlation between citations and the impact factor (rho = .483). According to Google Trends, the United States was the country that most researched GE. CONCLUSIONS: Based on this review, a more significant research interest in GE was observed in Europe, addressing the application of GE in locating severely calcified root canals.

Influence of temperature on the torsional properties of two thermally treated NiTi rotary instruments.

This study aimed to evaluate the influence of temperature on torsional strength and angular deflection of two experimental NiTi rotary instruments manufactured from Blue and Gold thermal treatments and with identical cross-sections. A total of 40 experimental NiTi instruments 25.06 and with a triangular cross-section and manufactured from Blue and Gold thermal treatments were used (n=20). The torsional test was performed in the 3 mm from the tip of the instrument according to ISO 3630-1. The torsional test evaluated the torsional strength and angular deflection to failure at room temperature (21°C ± 1° C) and body temperature (36°C ±1°C). The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). Data were analyzed using an unpaired t test for inter and intra-group comparison and the level of significance was set at 5%. The results showed that the body temperature did not affect the torsional strength and angular deflection of the instruments when compared with room temperature (P>0.05). However, at body temperature, the Blue NiTi instruments presented significantly lower angular deflection in comparison with Gold NiTi instruments (P<0.05). There was no significant difference regarding the torsional strength of the instruments at body temperature (P>0.05). The temperature did not affect the torsional strength of the instruments manufactured from Blue and Gold technology. However, the Blue NiTi instruments presented significantly lower angular deflection than Gold instruments at 36°C temperature.