Root Canal Preparation Research Articles

ENDODONTIC TREATMENT OF DECIDUOUS LOWER MOLAR DUE TO AGENESIS OF THE PERMANENT TOOTH GERM

The objective of this study was to describe the preparation of root canals with a rotary system in a lower molar (85). A 23-year-old female patient was referred to the office of an endodontic specialist for endodontic therapy of her primary lower molar (85). During the clinical examination, he reported pain on vertical percussion and occluso-distal composite resin restoration. Radiographic examination revealed deep restoration close to the distal pulp horn and agenesis of tooth 46. The probable diagnosis was acute apical periodontitis. Exploration of the root canals is carried out with a #10 C-pilot file, based on the apparent length of the tooth. Electronic odontometry was performed with the apex locator (Iroot Apex). The preparation of the root canals was carried out with a Prodesign Logic #30.05 file in the three root canals. During the preparation of each canal, 2% Chlorhexidine gel was used to facilitate the action of the nickel-titanium instruments. The filling of the root canals, carried out in the same session with the calibrated MX single cone technique (Tanari) associated with Bio-C Sealer cement (bioceramic cement). Clinical and radiographic follow-up, carried out two years after filling the canals, determined the success of endodontic therapy. It is concluded that the endodontic treatment of deciduous teeth must be carried out in accordance with the technical standards of endodontics, aiming at sanitization, modeling and hermetic filling, determining reabsorption of the bioceramic cement extravasated at the time of filling, which has been proven during 2 years of maintenance. completion of endodontic therapy.

Minimally invasive endodontic treatment through the labial/buccal cervical approach - protocol and case series.

Traditional access cavity preparation involves removing the roof of the pulp chamber and smoothing the dentin bulges at the root canal orifice, thereby creating straight-line access. However, this may damage more healthy dental tissue and reduce the tooth's fracture resistance. This case series presents a novel minimally invasive endodontic protocol for one maxillary canine and four mandibular premolars, which required root canal therapy due to labial/buccal cervical decay that caused pulpitis or periapical periodontitis. Our treatment protocol includes the following steps: preoperative assessment, removing decay in the labial/buccal cervical region, preparing an endodontic access cavity utilizing the affected region, establishing a working-length reference line using resin, cleansing the pulp horn with ultrasonic retro-preparation tip, root canal preparation, disinfection, obturation through the labial/buccal cervical access, and final resin restoration. Ideal root canal obsturation outcomes were achieved in all cases, while avoiding the abrasion of tooth tissue at the pulp chamber roof, caused by traditional endodontic access cavity methods. Minimally invasive endodontic treatment through the labial/buccal cervical approach offers clinicians new insights and options for endodontic access design.

Unveiling the mechanical performance of partially replaced coronal restorations in root canal-treated teeth: an in-vitro study

ObjectivesTo compare the mechanical performance of partially replaced (repaired) intra-coronal restorations to totally replaced ones in root canal-treated teeth.MethodsThirty maxillary second premolars were selected according to strict criteria, mounted on moulds, and had mesio-occluso-distal (MOD) cavities prepared. Resin composite restorative material was used to perform the initial restoration, followed by aging procedures using thermo-mechanical cycling fatigue to replicate six months of intraoral aging. The specimens were then randomly divided into two groups: a totally replaced restoration (TR) group (n = 15), which involved the preparation of a traditional endodontic access cavity after the complete removal of the pre-existing coronal filling; and a partially replaced restoration (PR) group (n = 15), which involved accessing the tooth through the pre-existing restoration without completely removing it. Root canal preparation and filling procedures were conducted, and the access cavity was sealed with a new resin composite restoration, followed by a new thermo-mechanical cycling aging procedure. Finally, the specimens were submitted to a static fracture test to measure specimen fracture strength and determine the failure mode pattern (repairable fracture or irreparable fracture). Chi-square and t-tests were used for statistical analysis.ResultsSignificant differences between the groups regarding their mechanical resistance were found. The average failure load of the TR group was 1115.13 N and 1330.23 N in the PR group (p = 0.002). Regarding the failure modes, the TR group exhibited eight irreparable fractures, while the PR group had four (p = 0.136).ConclusionsPartially replaced restorations presented higher fracture strength and led to fewer irreparable fractures when compared to totally replaced restorations in root canal-treated teeth.

Comparison of volumetric analysis between conventional and rotary files in the preparation of root canals in primary molars—an in vitro study

BackgroundTo compare and evaluate the efficacy of canal preparation and volumetric filling of primary molars instrumented by conventional hand K-file, ProAF baby rotary file and Kedo-S square file using cone beam computed tomography.Materials and methodsThirty freshly extracted human primary second molars were randomly divided into 3 groups of 10 teeth each. After access opening and working length determination, preoperative volume analysis was done using cone beam computed tomography (CBCT). The canals were then instrumented by either hand K-files, Pro AF Baby rotary files and Kedo-S square rotary files. Post operative volume analysis was performed using CBCT. All the canals were obturated using Metapex and scanned again using CBCT. Mean values of the pre- and post-operative canal volumes were analyzed using one-way ANOVA. Inter- and intra- group volumetric changes were analyzed statistically by post hoc test.ResultsThe mean difference in volume after canal preparation and obturation was the highest in the hand K-file group, followed by Pro AF Baby Gold group and the least in the Kedo-S square group. Inter and intra group comparison showed statistically significant differences for all the file groups used.ConclusionKedo- S square showed the least difference in preparation volume and better obturating volume compared to Pro AF baby gold file systems.

Effect of intracanal cryotherapy on post-operative pain in single-visit endodontic retreatment: a randomized clinical trial

BackgroundThis randomized clinical trial aimed to evaluate the effect of intracanal cryotherapy with 2–4 °C normal saline irrigation on post-operative pain after single-visit non-surgical root canal retreatment.MethodsForty-six single-rooted, single-canal teeth requiring non-surgical root canal retreatment were randomly assigned to two groups (n = 23): a cryotherapy group and a control group. All the treatments were completed during a single visit. A combination of nickel-titanium and stainless-steel files was used for the removal of gutta-percha and root canal preparation, and irrigation was performed using 5.25% NaOCl and 17% EDTA. The cryotherapy group had a final irrigation temperature of 2–4 °C for 5 min before root canal obturation, whereas the control group received irrigation at room temperature. Post-operative pain levels were assessed via the Numerical Rating Scale at 6, 18, 24, 48, 72, and 168 h (up to 7 days). The number of analgesics consumed at the same intervals was also recorded. Statistical analysis was performed using the Chi-Square test, Mann-Whitney test, and Independent Samples test, with the significance level set at 0.05.ResultsThere was a statistically significant difference in post-operative pain between the cryotherapy group and the control group at 6 h after treatment (P < 0.05). However, post-operative pain levels were not significantly different at 18, 24, 48, 72, or 168 h after treatment (P > 0.05). Additionally, there was no statistically significant difference between the groups in terms of analgesic intake (P > 0.05).ConclusionIntracanal cryotherapy can effectively reduce short-term post-operative pain, but it has no effect on long-term pain or the need for analgesics.

Microtomographic Analysis of the Biomechanical Performance of Thermally Treated Instruments in Flattened and Curved Root Canals.

This study aimed to evaluate, using micro-computed tomography (microCT), the impact of various mechanized systems on the geometry of the root canal system (RCS) and dentin thickness in mandibular first molars. The hypothesis proposed that different systems would produce significant variations in RCS preparation. Mesial and distal canals of mandibular molars were selected and divided into five groups (n=10) based on the system used: 2Shape (25.06), Reciproc Blue (25.08), ProTaper Ultimate (25.08), ProTaper Next (25.06), and Univy New (25.06). Biomechanical preparation was performed following each manufacturer's instructions. MicroCT scans were conducted before and after preparation to assess three-dimensional parameters (volume, surface area, SMI, and prepared root canal walls) and two-dimensional parameters (area, perimeter, diameters, roundness, and transportation). ProTaper Ultimate exhibited the greatest volume increase in mesial canals (1.73 ± 0.19), while ProTaper Next demonstrated the highest increase in distal canals (1.95 ± 0.25). Furthermore, ProTaper Ultimate resulted in the greatest dentin removal and the largest post-preparation area. Reciproc Blue achieved the best results for roundess and had the lower unprepared walls (15.3 ± 6.97). All systems produced comparable outcomes, with ProTaper Ultimate yielding the greatest volume increase and dentin removal, indicating a less conservative preparation. Reciproc Blue provided optimal roundness and minimized unprepared root canal wall surfaces.

Comparison of Canal Transportation by Two Rotary Systems, Neoniti vs. Wave One, Both Used with Reciprocal Motion

Objectives: Preserving the original canal morphology is the ideal goal during root canal preparation. This study aimed to compare canal transportation at various cross-sections using the Neoniti and Wave One Gold rotary systems, both applied with reciprocal motion. Materials and Methods: Forty acrylic S-shape canal simulator endo-blocks were used in this study. Two preparation protocols were applied: (1) Proglider (#16/0.02) followed by Wave One Gold (#20/0.07) and (2) GPS followed by A1#20 (reciprocal motion). The canals were dyed before and after preparation, and images were captured from both stages using blocks. These images were then superimposed using Adobe Photoshop to assess differences, and measurements were taken with Digimizer image analysis software. The data was analyzed using an independent samples T-test, with statistical significance set at P&lt;0.05. Results: Transportation was significantly greater in the middle third of the canal simulator in the group that was treated with Proglider (#16/0.02) followed by Wave One Gold (#20/0.07). However, no significant differences were observed in the coronal or apical thirds. Conclusion: While the manufacturer of Neoniti recommends using this system with continuous rotational motion, it can also be effectively utilized with reciprocal motion, yielding satisfactory results while respecting the canal anatomy.

Assessment of a Light-Curable Hydrogel to Be Used for Root Canal Obturation.

Root canal obturation involves filling of the chemomechanically prepared root canal space. Despite reduced microbial load, residual bacteria can still lead to reinfection and treatment failure. Currently, obturation techniques use a combination of gutta-percha and sealer, which requires the preparation of the root canal to specific sizes and tapers to enable the fitting of customized cones. This study aims to characterize the physical, chemical, and antimicrobial properties of a new light-curable injectable material (OdneFill, Switzerland) used to obturate the root canal. Odnefill and 2 root canal sealers (AH Plus and BioRoot RCS) were characterized by scanning electron microscopy (SEM) and energy-dispersive spectroscopy following exposure to chlorhexidine, sodium hypochlorite, and water. The flow, film thickness, radiopacity, solubility, and contact angle were evaluated. The susceptibility to microbial degradation was assessed by weight changes after contact with bacterial enzymes (lipase and cholesterol esterase). A multispecies biofilm composed of Streptococcus mutans, Enterococcus faecalis, Fusobacterium nucleatum, and Veillonella dispar was used to assess changes to the material microstructure (SEM). Further, bacterial viability in contact with the materials was evaluated using live/dead staining and confocal microscopy. A direct contact assay was carried out, and the utilization of the materials as a carbon source for the bacterial biofilm was also assessed. Statistical analysis was performed using 1-way analysis of variance and Tukey post hoc tests (P = 0.05). OdneFill was composed of an organic matrix with zirconium oxide filler. It exhibited comparable physical properties to AH Plus and BioRoot RCS and was stable in contact with irrigating solutions and with the bacterial enzymes (cholesterol esterase and lipase). Its antimicrobial characteristics were better than those of AH Plus when placed in contact with a multispecies biofilm. Based on the findings, OdneFill presents itself as suitable root canal-filling material and warrants further clinical investigation.

SIZE OF APICAL CONSTRICTION IN DIFFERENT TYPES OF PERMANENT TEETH

Background: The final size of the apical root canal preparation has been a contraversion issue for a long time. The enlargement of the apical portion of the root canal may severely affect endodontic prognosis. Preparation of the apical zone to a larger file size may negatively affect the ability to control the filling material during root canal obturation. An excessively expanded apical zone increases the risk of overfilling, which has been shown to be associated with a reduced success rate. This article aims to review research papers on the anatomical natural diameter of the apical root canal constriction, which is the endpoint of the endodontic preparation and should determine the appropriate size of the apical and root canal preparation. Review Results: In the review, we have included various scientific articles from recent years that comment on the size and shape of the apical constriction in different groups of teeth. We have summarized the results in graphs that give a visual idea of ​​the differences in the sizes of the different apical constrictions. Conclusion: The root apex is morphologically a challenging zone. The endodontist should have detailed knowledge of anatomic variation and mechanics challenges involved in treating apical third to manage endodontic therapy effectively. More research is needed to elucidate the influence of the size of the apical constriction on the apical stop preparation.

A Comparative Study of Temperature Variations in Incisor Root Surfaces During Root Canal Preparation Using Various Rotary Systems and Irrigation Protocols.

Background/Objectives: This study investigates the temperature changes on the external root surface during root canal preparation using different rotary systems and assesses the impact of irrigation temperatures. Methods: Sixty extracted human maxillary incisors were divided into four groups based on the rotary system used: ProTaper Next (Dentsply Sirona, Ballaigues, Switzerland), Reciproc Blue (VDW GmbH, Munich, Germany), WaveOne Gold (Dentsply Sirona, Ballaigues, Switzerland), and TruNatomy (Dentsply Sirona, Ballaigues, Switzerland). These systems differ in cutting efficiency and design. Temperature measurements during instrumentation and irrigation were recorded using a FLIR E60bx thermal camera (Teledyne FLIR LLC, Hudson, NH, USA). Irrigations were conducted with sodium hypochlorite at room temperature and heated to 60 °C. Results: The ProTaper Next group exhibited the highest average temperature increase during instrumentation (5.2 °C), followed by WaveOne Gold (4.3 °C), Reciproc Blue (3.7 °C), and TruNatomy (2.8 °C). During irrigation with heated sodium hypochlorite, temperature rises recorded were 6.8 °C for ProTaper Next, 5.9 °C for WaveOne Gold, 5.2 °C for Reciproc Blue, and 4.1 °C for TruNatomy. Statistical analysis revealed a significant negative correlation between dentin thickness and temperature rise, with r-values ranging from -0.62 to -0.87 across the groups. No significant correlation was found between canal diameter and temperature change, indicating that the canal's size does not influence the thermal impact as much as the properties of the rotary system and irrigation temperature. Conclusions: Different rotary systems produce varying levels of temperature increases on the external root surface, influenced significantly by the thickness of the dentin and the temperature of the irrigation solution. These variations necessitate careful selection of instrumentation and irrigation protocols to minimize potential thermal damage to surrounding periodontal tissues.

The effect of different activation irrigations on intracanal smear layer removal: a vitro study.

To compare the effect of syringe irrigation technique, passive ultrasonic activation technique, EDDY activation technique and Er,Cr,YSGG laser activation technique on smear layer removal in root canals in vitro. Forty mandibular first premolars with single canal were collected from patients in Qingdao Stomatological Hospital affiliated to Qingdao University. After root canal preparation with ProTaper Universal to F3, they were randomly divided into four groups (n = 10) according to different activation irrigations for the final washing: syringe irrigation (SI), passive ultrasonic activation (PU), EDDY activation (EDDY) and Er,Cr,YSGG laser activation (YSGG). Finally, all the crowns of them were cut off and the root length was trimmed to 15mm. The roots were split longitudinally and observed with scanning electron microscope (SEM) for assessment of smear layer removal in different parts of the root canal. All groups showed similar effects for cleaning the root canals in the coronal thirds (P > 0.05). For cleaning the root canals in the middle thirds, PU group, EDDY group and YSGG group showed similar effects, (P> 0.05). They were more effective than SI group (P < 0.05). For cleaning the root canals in the apical thirds, PU group and EDDY group showed similar effects (P> 0.05). They were more effective than SI group (P < 0.05). YSGG group was more effective than other groups (P < 0.05). Er,Cr,YSGG laser activation technique can remove smear layer of root canals effectively. The cleaning effect of the passive ultrasonic activation technique, EDDY activation technique is better than that of syringe irrigation technique.

Micro-computed tomographic evaluation of dentinal microcracks in response to progressive taper enlargement in root canals of maxillary molars.

To investigate the development of dentinal microcracks resulting from the progressive enlargement of the buccal canals of maxillary molars with and without the MB2 canal employing instruments with the same tip and four different tapers. Twenty maxillary molars with (n = 10) and without (n = 10) the MB2 canal underwent micro-CT scanning. Their mesiobuccal and distobuccal canals were sequentially enlarged using nickel-titanium instruments with sizes 25/.03, 25/.05, 25/.06 and 25/.08v. Subsequent scans were conducted after each canal enlargement. The preoperative scans were coregistered with their respective datasets, and the cross-sectional images were carefully examined to identify dentinal defects. This process, conducted twice at two-week intervals, involved two examiners. Intra- and inter-examiner calibrations were validated using the Kappa index. The incidence of microcracks was reported as a percentage frequency. The intra- and inter-examiner Kappa values were 0.85 and 0.88, respectively, indicating excellent agreement. Dentinal microcracks were detected in 1206 out of 42 975 cross-sectional image slices (2.8%). Molars with MB2 canal exhibited more slices (4.5%) than teeth without MB2 (0.9%). Every dentinal microcrack observed in the images after root canal preparation was already present in the corresponding images takenbefore root canal preparation. The progressive enlargement of root canals using instruments with different tapers did not induce the formation of new dentinal microcracks in maxillary molars, regardless of the presence of the MB2 canal.

Comparative Retreatment Efficacy of Two Multi-File Systems with Different Access Cavity Designs: A Micro-Computed Tomography Study.

Background and Objectives: The access cavity design and instrumentation system could affect the remaining root canal obturation materials in root canal retreatment. This study aimed to evaluate the efficiency of two different multi-file systems in removing obturation materials with two different access cavities utilizing micro-CT scanning. Materials and Methods: Conservative access cavity (CAC) preparation was performed for 80 mandibular premolars. Then, root canal preparation was employed followed by obturation. The retreatment process began by dividing the samples into two separate groups: conservative (CAC) and traditional (TAC) access cavities. Subsequently, these groups were assigned to eight distinct subgroups (n = 10): Group 1; TAC and ProTaper retreatment system (PTR) with ProTaper Next (PTN); Group 2, TAC and PTR + ProTaper Ultimate (PTUL); Group 3, TAC and PTN; Group 4, TAC and PTUL; Group 5, CAC and PTR + PTN; Group 6, CAC and PTR + PTUL; Group 7, CAC and PTN; and Group 8, CAC and PTUL. The samples underwent micro-CT scans before and after the retreatment process, and the volume and percentages of remaining root canal filling material were calculated. Statistical analysis of the data was performed, and significance was determined at the 5% level. Results: The influence of the access cavity design (p = 0.500), the ProTaper system (p = 0.138), and the interaction of these variables (p = 0.513) was insignificant. However, group 3 (TAC and PTN) showed the highest percentage of remaining obturation materials at 29.53%, contrasting with group 6 (CAC and PTR + PTUL). Conclusions: Neither retreatment procedure succeeded in completely removing filling materials. Nevertheless, the impact of access cavity design, different multi-file systems, and their interaction on the remaining root canal obturation materials was deemed insignificant.

Comparative Evaluation of Crack Propagation During Root Canal Preparation in Primary Molar with Manual Instrumentation, ProTaper Universal and ProTaper Next Rotary File Systems: An in vitro Study.

Root canal preparation with rotary files causes dentinal cracks in root canals of primary teeth affecting their longevity. Nickel-titanium rotary files have been widely used for root canal preparation in primary teeth. The present study compared occurrence of dentinal microcracks in root canals of extracted primary molar teeth prepared using Hedstrom (H) files, ProTaper Universal rotary files, and ProTaper Next rotary file systems. In this in vitro experimental study, 80 primary molar mesial root canals were randomly divided into four groups of 20 canals each (n=20). Group I was prepared with H files. Group II was prepared with ProTaper Universal rotary files using shaping files SX and S2. Group III was instrumented with ProTaper Next rotary files X1 and X2 while Group IV was left unprepared and served as control. Roots were stained with 1% methylene blue solution and sectioned perpendicular to the long axis at 2mm, 4mm, and 6mm from the apical foramen. Slices obtained were examined under the stereomicroscope. Data obtained were subjected to statistical analysis using chi square tests. Dentinal microcracks were observed in groups prepared using H files, ProTaper Universal, and ProTaper Next rotary files. Highest percentage of cracked root canals (20%) was seen in Group I, prepared by H files. These cracks were complete in nature, found in apical sections and statistically significant (p= 0.016). Group III prepared with ProTaper Next showed 10% dentinal cracks, followed by ProTaper Universal group with 5% cracked root canals. H files may be considered more aggressive at apical third due to complete cracks produced.

The Novel Assessment to Explore the Cutting Performance of Rotary Instruments Using Dynamic Finite Element Analysis With Failure Mode.

The separation of Nickel-Titanium (NiTi) endodontic instruments due to excessive torque adversely affects treatment outcomes. Previous studies have analyzed torque values under static conditions and failed to accurately simulate the dynamic conditions of instruments within root canals. This study aimed to apply a novel finite element analysis (FEA) to assess the real-time dynamic performance of NiTi endodontic instruments during operation in root canals. In this study, three-dimensional geometric models of commercial NiTi endodontic instruments (ProTaper Universal) and simulated root canals were developed. In the first part, dynamic analyses of the instruments operating within root canals were simulated using finite element fracture theory and validated through experimental methods. To assess the consistency between the experimental results generated by different instruments (ProTaper Universal SX, S1, S2, and F1) and the FEA results, we utilized Bland-Altman plots for visualization and the Intraclass Correlation Coefficient for comparing continuous data. In the second part, the FEA was employed to establish a safe and efficient sequence for root canal shaping. The findings indicated a similar trend between the analyzed and experimental groups. The Bland-Altman plot demonstrated a high level of consistency, with Intraclass Correlation Coefficient values ranging from 0.6407 to 0.9351. To evaluate the dynamic performance of commercial endodontic instruments in canals, the instruments experienced excessive torque values and significant loading. Based on torque control, new sequences for safe and effective root canal preparation were proposed. FEA with failure mode was demonstrated to simulate the real-time dynamic performance of instruments working in the simulated canals. This assessment offers guidance for clinical protocols and the development of innovative instruments with improving safety and efficacy in endodontic treatments through computer-aided techniques.

Atomic Force Microscopic Evaluation of Surface Topographies of Various Rotary Files in Root Canal Preparation in Molar Teeth

ABSTRACT Background: The efficiency and safety of root canal preparation are significantly influenced by the surface topographies of rotary files. Atomic force microscopy (AFM) provides high-resolution imaging that can reveal detailed surface characteristics of these instruments. Materials and Methods: In this study, three types of rotary files (File A, File B, and File C) were used to prepare the root canals of extracted human molar teeth. A total of 30 molar teeth were divided into three groups (n = 10) and prepared using one of the three rotary files. After preparation, the rotary files were analyzed using AFM to measure surface roughness parameters including average roughness (Ra), root mean square roughness (Rq), and maximum peak height (Rp). Statistical analysis was performed using ANOVA and post hoc tests to compare the differences between the groups. Results: The AFM analysis revealed significant differences in the surface topographies of the rotary files. File A exhibited a Ra of 150 nm, a root mean Rq of 180 nm, and a maximum peak height Rp of 300 nm. File B showed an average roughness (Ra) of 200 nm, a root mean Rq of 230 nm, and a maximum peak height (Rp) of 350 nm. File C had an average roughness (Ra) of 170 nm, a root mean Rq of 210 nm, and a maximum Rp of 320 nm. Statistical analysis indicated that File B had significantly higher roughness parameters compared to File A and File C (P &lt; 0.05). Conclusion: The surface topographies of rotary files vary significantly, which may impact their performance in root canal preparation. File B, with the highest roughness parameters, may pose a greater risk of canal wall damage and debris retention. These findings underscore the importance of selecting appropriate rotary files to optimize endodontic treatment outcomes.

Periradicular repair after single-visit root canal treatment using sonic irrigant activation of teeth with apical periodontitis.

This study aimed to explore whether using sonic irrigant activation during endodontic treatment favors periradicular repair in teeth with apical periodontitis. One clinician treated 140 posterior (either premolar or molar) asymptomatic teeth with periapical lesions: 70 were randomly assigned to the sonic activation with EndoActivator (EA) group, and 70 were treated by conventional needle irrigation (CNI). Both groups underwent chemomechanical root canal preparation using 35/04 diameter rotary files and 2.5% NaOCl as the irrigant. NaOCl was sonically activated in the EA group, and the final irrigation with NaOCl was performed using a 30-gauge side-perforated needle in the CNI group. All root canal obturations were performed with lateral compaction. All patients were followed up for 12 months. Success was determined based on both healed and healing cases. The chi-square or Fisher's exact test was used to compare success rates and outcome-influencing factors between groups. The recall rate was 131 (94%). At 12 months, 50 teeth (77%) were considered healed, 12 teeth (18%) as healing, and three (5%) as failed in the EA group, while 43 teeth (65%) were considered healed, 17 (26%) as healing, and six (9%) as failed in the CNI group. Verbal Rating Scale scores were significantly lower in the EA group than in the CNI group on postoperative days 1 (p < 0.0001) and 2 (p = 0.0002). Postoperative Periapical Index scores were significantly lower in the EA group than in the CNI group (p = 0.0023). Postoperative lesion sizes were also significantly smaller in the EA group (0.7 [0.2-11.7] mm) than in the CNI group (1.7 [0.5-11.5] mm; p = 0.0118). While the success rate was higher in the EA group (62 [95%]) than in the CNI group (60 [91%]), the difference was not significant (p = 0.492). The periradicular repair of posterior teeth with apical periodontitis demonstrated the efficacy of EndoActivator on treatment outcomes and reduced postoperative pain. These results suggest the adjunctive use of sonic activation to enhance the decontamination of the root canal system during the chemomechanical stage. This clinical trial is the first to evaluate the effects of sonic activation on postoperative healing. Sonic activation with the EndoActivator can reduce postoperative pain and accelerate the healing of the periapical tissues.

Influence of different kinematics on shaping ability and accumulated hard tissue debris: an ex vivo study.

To determine the shaping ability, the amount of accumulated hard tissue debris (AHTD) and untouched area is generated by different kinematics through micro-CT. Thirty-two mesial roots of mandibular molars with Vertucci type IV were pre-scanned through micro-CT evaluation and randomized to one of the four experimental groups according to the kinematics tested: Continuous Rotation (CR), Reciprocation (REC), Optimum Torque Reverse (OTR) and Jeni motion. The root canal preparation was performed with HyFlex EDM (Coltène/Whaledent AG) up to OneFile. After each file used, irrigation was performed with 2mL 5.25% NaOCl for 1min. The final rinse was performed with 1ml of 5.25% NaOCl followed by a 1ml of 17% EDTA and, 1ml of distilled water. Then, the samples were scanned and the images, before and after preparation, were superimposed and analyzed to determine the AHTD, untouched areas, canal transportation, centering ability, and shaping time. Data were statistically analyzed using Kruskal-Wallis test and Dunn post hoc with p < 0.05. No significant differences were detected among the tested kinematics in terms of untouched areas, AHTD, canal transportation and shaping time (p > 0.05). Significantly more untouched areas were detected in the coronal third compared to the middle (p = 0.0301) and apical ones (p = 0.0399) under continuous rotation. Moreover, a significantly higher centering ratio in the middle third compared to the apical was observed for Jeni motion (p = 0.0207). The tested kinematics showed similar untouched areas, AHTD, shaping ability and shaping time. All motions determined an appropriate mechanical preparation; yet, none of them was able to prepare all canal walls and keep the root canals completely free from hard tissue debris.

Assessing Dentinal Microcracks using Micro-CT after Root Canal Preparation with Different Rotary Endodontic File Systems

ABSTRACT Objective: This study aimed to evaluate the propagation of dentinal microcracks in the mesiobuccal (MB) and mesiolingual (ML) canals following root canal preparation using two different rotary endodontic file systems, TruNatomy (continuous rotation) and MicroMega ONE RECI (reciprocating motion), using micro-computed tomography (micro-CT). Materials and Methods: Fifty freshly extracted human mandibular first and second molars were selected based on specific inclusion criteria. Root canal preparation was confined to the MB and ML canals in mesial roots of mandibular molars (Vertucci Type IV canal configurations) using TruNatomy and MicroMega ONE RECI systems. Pre- and post- preparation scans were taken for all the specimens using micro-CT to identify and measure dentinal microcracks. Statistical analysis was performed using a t-test and Fisher’s exact test, with significance set at P &lt; 0.05. Results: The results indicated no statistically significant differences between the two systems in terms of microcrack formation or propagation. In the ML canal, 8.0% of teeth prepared with TruNatomy and 12.0% with MicroMega ONE RECI exhibited microcracks (P = 0.643). In the MB canal, microcracks were found in 12.0% of the TruNatomy group and 8.0% of the MicroMega ONE RECI group (P = 0.643). Both systems showed a significant increase in canal volume, but no significant differences between the instruments (P &lt; 0.001). Conclusion: Both TruNatomy and MicroMega ONE RECI demonstrated similar outcomes regarding dentinal microcrack formation and propagation in the MB and ML canals, with no significant differences. Both systems were effective in enlarging the canals while preserving the natural canal anatomy. These findings suggest that the choice of instrumentation system can be guided by clinical ease and efficiency as both systems offer comparable mechanical effects on dentin integrity during root canal preparation.

Comparative Evaluation of Microcrack Formation by K Files Using Mechanical Technique with Help of Reciprocating Contra-Angle Handpiece and Manual Technique: An Invitro Study

Introduction Effective root canal preparation is essential for successful treatment, focusing on thorough cleaning and shaping to prevent complications like vertical root fractures. Different tools, such as stainless steel and nickel-titanium files, offer advantages and drawbacks, impacting the risk of dentinal microcracks. This study examines the incidence of these cracks using both manual and reciprocating techniques with K files.  Material and Method This study involved 150 mandibular premolars, divided into five groups to evaluate dentinal crack formation with different file systems. Groups included manual and mechanical instrumentation with stainless steel (S.S.) and nickel-titanium (NiTi) files, with one control group. After standard root canal preparation and irrigation, each root was sectioned and examined under a stereomicroscope to document crack formation. Data was analysed using Chi-square test, and Fisher's Exact test.  Result There is no statistical significant difference among groups.  Conclusion Maintaining root integrity in root canal treatment is vital, with similar crack formation seen in both manual and reciprocating techniques. Reciprocating handpieces offer a cost-effective, efficient option, beneficial for student training in modern endodontics.