Phase transformation behavior and mechanical properties of HyFlex EDM nickel-titanium endodontic rotary instrument: Evaluation at body temperature.

Background/purpose: Temperature-dependent phase compositional changes influence the mechanical properties of heat-treated nickel-titanium (NiTi) rotary instruments. This study evaluated the phase composition, bending properties, and cyclic fatigue resistance of HyFlex EDM NiTi rotary instruments against differently heat-treated and non-heat-treated NiTi instruments at body temperature (BT). Materials and methods: HyFlex EDM OneFile (EDM) instruments, heat-treated HyFlex CM (CM) and Twisted File (TF) instruments, and non-heat-treated K3 instruments (size #25/.08) were subjected to differential scanning calorimetry, and the martensitic, R-phase, and reverse transformation starting and finishing temperatures were determined. A cantilever bending test and a cyclic fatigue test were conducted at BT (37 °C ± 1.0 °C), and the bending load and number of cycles to failure (NCF) were recorded. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). Results: TF and K3 had reverse transformation finishing temperatures lower than BT, while those for EDM and CM were higher than BT. The bending loads at a 0.5 mm deflection were in the order of EDM < TF < CM < K3 (P < 0.05), and those at a 2.0 mm deflection were EDM < CM and TF < K3 (P < 0.05). EDM had the highest NCF among the four instruments (P < 0.05). Conclusion: The EDM instrument had a reverse transformation finishing temperature higher than BT indicating its martensite/R-phase composition at BT. The EDM instrument had superior flexibility and greater resistance to cyclic fatigue than the CM, TF, and K3 instruments at BT.

The effect of apical patency on postoperative pain following endodontic therapy: A systematic review and meta-analysis.

This systematic review and meta-analysis aimed to determine whether apical patency increases postoperative pain after endodontic therapy. This study explored the degree and incidence of postoperative pain during root canal therapy, as well as the number of required analgesic doses. We searched PubMed, Scopus, Embase, Web of Science, Cochrane Library, and gray literature from the date of database inception until May 2023. RevMan 5.4 software was used for data analysis. Twelve studies were considered eligible for meta-analysis. The mean pain scores on days 1 (mean difference [MD] = -1.69) and 2 (MD = -0.85) differed significantly between the apical patency and non-patency groups. The odds for pain after 24 h were significantly lower (OR 0.59) in the apical patency group than in the non-patency group. Furthermore, the mean number of required analgesic doses was not significantly different between the two groups. In conclusion, apical patency significantly alleviated postoperative pain (low-quality evidence) and reduced the incidence of pain (moderate evidence). However, high-quality randomized controlled trials are required to validate these findings.

Comparative evaluation of ethanol versus citric acid in removal of oil-based calcium hydroxide from the apical third of root canal system.

Objectives: To evaluate the effectiveness of ethanol compared to citric acid in the removal of oil-based calcium hydroxide from the apical third of the root canal system using passive ultrasonic irrigation. METHODS: The in vitro study was conducted from September to October 2021 at the dental clinics of the Aga Khan University Hospital, Karachi, and comprised single-rooted teeth that were selected from institutional bank of extracted teeth. They were randomly divided into group A having 70% ethanol + passive ultrasonic irrigation, group B 10% citric acid + passive ultrasonic irrigation, group C positive controls and group D negative controls. The specimens were sectioned at 1mm and 3mm from the apex and examined under a dental operating microscope. A single examiner scored the specimens on two different occasions. Data was analysed using SPSS 25. RESULTS: Of the 90 teeth, there were 40(44.4%) in each of the 2 experimental groups and 5(5.5%) in each of the 2 control groups. At 3mm apical sections, ethanol was significantly more effective in the removal of oil-based calcium hydroxide (p=0.01). However, at 1mm from the apex, there was no significant difference between the experimental groups (p=0.064). Intragroup comparison showed that for groups A and B, residual medicament at 1mm sections was significantly greater than at 3mm sections (p<0.001, p=0.003). CONCLUSIONS: Neither irrigant showed complete removal at 1mm and 3mm from the apex. However, at 3mm apical sections, 70% ethanol was significantly more effective compared to 10% citric acid.

Comparison of the Antibacterial Effect of AH26, Adseal and Beta RCS Root Canal Sealers against Enterococcus Faecalis, an in Vitro Study.

Objectives: Antibacterial activity against endodontic pathogens is a desirable feature for root canal sealers. The objective of this study was to compare the antibacterial effect of three resin-based endodontic sealers (AH26, Adseal, and Beta RCS) against Enterococcus faecalis in vitro. Materials and Methods: The antibacterial properties of the sealers were assessed against E. faecalis using agar diffusion test (ADT) for fresh state (N=10) and direct contact test (DCT) for freshly-mixed and set states of the materials (N=10). In ADT, the diameter of the zones of inhibition was measured after 24h of contact. In DCT, the colony-forming units of the bacteria were counted after 30 minutes and 180 minutes of exposure. The results were analyzed with two-way ANOVA and independent sample t-test. P<0.05 was considered significant. Results: Regarding DCT results, all test materials indicated an antibacterial effect, both in freshly-mixed and set states. The highest antibacterial effect was related to Adseal, whereas the lowest was observed in Beta RCS. There was a significant difference between all study groups (different sealers, setting states, and contact times; P<0.001), except for freshly-mixed AH26 and Adseal at 180 minutes (P>0.05). According to ADT, AH26 and Adseal represented the widest and the smallest inhibition zones, respectively (P<0.001). Conclusion: Within the limitations of this in vitro study, AH26, Adseal, and Beta RCS showed antibacterial effects against E. faecalis in both freshly-mixed and set states. The antibacterial effect increased over time in all of the studied sealers.

Novel bioactive nanospheres show effective antibacterial effect against multiple endodontic pathogens.

Aim: The current study evaluated the antibacterial activity of a newly developed quaternary ammonium polymethacrylate (QAPM)-containing bioactive glasses (BGs) via a two-step method by our group, namely BGs-HAEMB, and explored its cytotoxicity and biocompatibility. Methods: The antibacterial effects of the BGs-HAEMB against planktonic bacteria, bacterial biofilm formation, and experimental root canal biofilms of persistent pathogens (Enterococcus faecalis, Streptococcus sanguis and Porphyromonas endodontalis) associated with endodontic infection were evaluated in vitro by agar diffusion tests, direct contact tests and live/dead staining. The cytotoxicity and biocompatibility of BGs-HAEMB were evaluated by CCK-8 assays in vitro and a skin implantation model in vivo. Results: Compared to three clinically used endodontic sealers (Endofill, AH Plus, and iRoot SP), BGs-HAEMB exhibited the relatively strongest antibacterial effect against E. faecalis, S. sanguis and P. endodontalis after sitting for 14 and 28 days (P < 0.01). SEM images and CLSM images also showed that for each tested bacteria, BGs-HAEMB killed the most microorganism among all the experimental groups, regardless of treatment for 7 days or 28 days (P < 0.05). Besides, the BGs-HAEMB-treated groups showed a relatively low cytotoxicity (RGRs ranging from 88.6% to 102.9%) after 1, 3, and 7 days of exposure. Meanwhile, after 28 days of implantation, the inflammatory grade in BGs-HAEMB treated group was assessed as Grade I, in which the average numbers of inflammatory cells (6.7 ± 2.1) were less than 25. Conclusions: BGs-HAEMB exerted a long-term and stable antibacterial effect. The remarkable biocompatibility of BGs-HAEMB in vitro and in vivo confirmed its possible clinical application as a potential alternative in the development of the next generation of endodontic sealers.

Effect of the timing of primary endodontic treatment and dosage of radiation therapy on the filling material removal.

This study investigated the effect of the timing of primary endodontic treatment and dosage of radiotherapy on the remaining filling material (RFM) during endodontic reintervention. 60 single-rooted human mandibular premolars were distributed into five groups (n = 12), according to the timing and dosage of radiation (55Gy or 70Gy): NegativeCG-non-irradiated teeth; Endo-pre-RT55/70-obturation before irradiation (55Gy or 70Gy); Endo-post-RT55/70-obturation and reintervention after irradiation (55Gy or 70Gy). Roots were cleaved and analysed under stereomicroscope and Scanning Electron Microscope to quantify (%) the RFM. Experimental groups had a significantly greater amount (p < 0.05) of RFM in the middle and apical thirds than the control group, except for Endo-pre-RT55 in the middle third (p < 0.0001). The apical third had greater amount of RFM (p < 0.05). Radiation therapy, before and after primary endodontic treatment, increased the amount of RFM, regardless of the dose delivered. When necessary, reintervention preferably must be performed before radiation therapy.

Radiographic Evaluation Factors That Influence the Decision of the Tooth Extraction Method.

INTRODUCTION: A simple tooth extraction method usually involves using elevators and forceps to remove the tooth easily. In contrast, a surgical extraction method requires utilizing a straight handpiece to facilitate the tooth extraction, either removing bone or sectioning the tooth into pieces. OBJECTIVE: In this research, we aim to diagnose a tooth radiographically before extraction and determine certain factors to observe which extraction method might be more feasible, either simple or surgical. METHODOLOGY: This study followed a retrospective cross-sectional study design. The x-ray radiographs (periapical (PA) or panoramic) were collected from the R4 system in the university dental hospital for data collection. Different radiographic influencing factors were measured, such as bone density, bone level, endodontic involvement (RCT/post and core), crowned or remaining root, and root morphology. Statistical associations were performed using SPSS (IBM Corp., Armonk, NY) with a one-way ANOVA test. RESULTS: There were 62 cases with 47 simple and 15 surgical extractions. There was a non-significant (p>0.05) association between the measured factors and the extraction method, either simple or surgical tooth extraction. Although bone density measurements showed a slight tendency toward PA lesions and simple tooth extraction. CONCLUSION: There was no significant association between the factors and extraction methods. Future research is required to determine whether or not preoperative radiographic evaluation can influence the decision for the tooth extraction method.

An Ex-vivo Comparative Study to Evaluate the Efficacy of Three Root Canal Irrigation Systems in Reduction of Enterococcus Faecalis.

Aim: The purpose of this ex-vivo study is to evaluate the efficacy of three irrigation techniques in the reduction of E. faecalis in root canal. Materials and Methods: Eighty healthy maxillary anteriors were employed in this investigation. The bacteria E. faecalis was left on teeth for 7 days while they were kept. Once teeth were contaminated, they were randomly divided into three groups of 20 for experimentation and a control group of 20 for comparison. NaviTip FX was used to irrigate Group I, the Max-I-probe was used to water Group II, and the Endovac system was used to water Group III. The number of colony forming units (CFUs) was determined by growing bacteria from root canal samples for 2 days in Brain heart infusion agar after chemo-mechanical operations. Results: There was a substantial decrease in bacterial numbers across all experimental groups compared to group IV (control). Group III (Endovac) had the fewest bacterial colonies among the test groups. There were no discernible changes between Group I (the Navitip FX) and Group II (the Max I probe). Conclusion: Endovac was the most effective of the three irrigation methods for reducing CFUs. This study's findings lend credence to the idea that the apical negative pressure approach has more potential than the conventional irrigation delivery system for achieving an enhanced antibacterial impact.

Morphological Variation of Mandibular Molars in Rohilkhand Population: An Original Research.

Introduction: In-depth knowledge of common and aberrant pulp morphology is essential for appropriate diagnosis and treatment planning before commencing root canal treatment. The radicular morphology of mandibular molars has been extensively studied. Considerable variation in the number of canals and roots found in these teeth has been reported. Aim: The purpose of this study is to investigate the root canal morphology of the mandibular molars among the Rohilkhand population using Dentascan. Materials and Methods: Dentascan images of mandibular molar were taken from 99 extracted teeth that were collected from the Department of Oral Surgery and Maxillofacial Surgery, Institute of Dental Sciences, Bareilly, and private clinics. The examination of root canal systems of the teeth was based on Vertucci's classification. Results: The mandibular molar (n = 99) were taken. Out of the 99 teeth examined, three canals were seen in 60 (60.6%) teeth, four canals in 39 (39.4%) teeth, 3% had extra distal roots, and 6% with C-shaped canals. Conclusion: Among mandibular first molars, only 3% had three roots. Mesial roots of the first molar typically present with two canals and two apical foramina with type IV or II canal configuration. Most distal roots of the first molar presented with a type I canal configuration. The remainder were distributed mainly between types II, IV, III, and V. Among 99 mandibular molars, 6% had single C-shaped roots.

Comparing Patient Outcomes for Teeth Treated with Traditional Root Canal Therapy Versus Pulpotomy: A Randomized Controlled Trial.

Background: Root canal therapy (RCT) and pulpotomy are two common treatment modalities for managing dental pulp infections, but their comparative effectiveness in terms of patient outcomes remains unclear. This root canal therapy (RCT) aimed to assess and compare patient outcomes between teeth treated with traditional RCT and pulpotomy. Materials and Methods: In this single-center RCT, a total of 120 patients presenting with symptomatic dental pulp infections were randomly assigned to either the RCT group or the pulpotomy group. The RCT group received conventional root canal treatment, which involved complete removal of infected pulp and obturation of the root canals. The pulpotomy group underwent a procedure where only the coronal pulp tissue was removed, followed by the placement of a medicament. Pain levels, infection resolution, and tooth survival were assessed at 6 months and 1 year posttreatment. Results: At the 6-month follow-up, patients in the RCT group reported significantly lower pain scores (2.5 ± 0.8) compared with the pulpotomy group (4.3 ± 1.2, P < 0.001). Infection resolution was also higher in the RCT group (92%) compared with the pulpotomy group (78%) at 6 months. Tooth survival rates at 1 year were significantly higher in the RCT group (95%) compared with the pulpotomy group (81%, P < 0.05). Conclusion: This RCT demonstrates that traditional RCT is superior to pulpotomy in terms of pain reduction, infection resolution, and tooth survival. Patients who underwent RCT experienced less pain, faster infection resolution, and better tooth survival rates compared with those who received pulpotomy. These findings support the use of RCT as the preferred treatment modality for dental pulp infections.

Investigation of the Potential of Nanoparticles as a New Drug Delivery System for Endodontic Treatment: An In Vitro Study.

Background: Endodontic treatment involves the removal of infected dental pulp and subsequent disinfection of the root canal system. The effectiveness of drug delivery systems in root canal disinfection is critical for successful treatment outcomes. This in vitro study explores the potential of nanoparticles as a novel drug delivery system for endodontic treatment. Materials and Methods: Nanoparticles were synthesized using a biocompatible polymer and loaded with an antimicrobial agent. A total of 60 extracted human teeth were prepared to create standardized root canal infections. The teeth were randomly divided into three experimental groups: (1) conventional irrigation, (2) nanoparticle irrigation, and (3) control (no irrigation). The root canals in each group were irrigated with their respective solutions for 5 minutes. After treatment, microbial samples were collected from the root canals and cultured for colony-forming unit (CFU) analysis. The depth of penetration of nanoparticles into dentinal tubules was assessed using scanning electron microscopy (SEM). Results: The conventional irrigation group showed a reduction in microbial load from an average of 7.8 × 10^5 CFU/mL (SD ± 1.2 × 10^5) to 3.4 × 10^4 CFU/mL (SD ± 7.9 × 10^3) (P < 0.001). In contrast, the nanoparticle irrigation group exhibited a more significant reduction, with a decrease in CFU to 1.2 × 10^3 CFU/mL (SD ± 4.2 × 10^2) (P < 0.001). SEM analysis revealed deep penetration of nanoparticles into dentinal tubules, reaching an average depth of 150 µm. Conclusion: Nanoparticles loaded with antimicrobial agents demonstrated superior efficacy in reducing microbial load within root canals compared to conventional irrigation. Their ability to penetrate dentinal tubules suggests their potential as an innovative drug delivery system for endodontic treatment. Further research and clinical trials are warranted to validate these promising in vitro results and assess the safety and efficacy of nanoparticles in clinical practice.

Comparative Evaluation of Sealing Ability of Different Type of MTA as Root-End Filling Materials Using Dye Penetration Technique - An In Vitro Study.

Introduction: The main goal of the root-end filling material is to create a hermetic seal to protect against microbes and their by-products. Excellent biocompatibility and sealing ability are characteristics of MTA developed by Torabinejad et al. This study aimed to compare the sealing ability of different type MTA as root-end filling material using dye penetration technique. Material and Method: One-twenty (N = 120) extracted human maxillary anterior teeth were decontaminated, cleaned, and decoronated. Endodontic treatment and root-end resection were done. Then root-end cavity was prepared and filled with tested materials (N = 30). A calibrated stereomicroscope was used to evaluate linear measurement. All data were tabulated and statistically analyzed with a level of significance set at P < .05. Result: This order of increasing microleaks was observed: MTA Angelus < MTA Plus < PRO-Root MTA < Control group. There was a statistically significant difference in mean microleakage in MTA Angelus and MTA Plus groups (P = 0.040). MTA Angelus shows the least microleakage among all the bioceramic material groups. Conclusion: Although the sealing ability of MTA Angelus is superior to MTA Plus, PRO-Root MTA. MTA Plus, PRO-Root MTA could be considered an acceptable alternative to MTA Angelus in peri-radicular surgeries.

Sealing Ability Comparison of Three Different Obturating Systems to Intraradicular Dentin-An In Vitro Stereomicroscopic Study.

Background: Different obturation techniques are being used to improve canal sealing, thereby minimizing marginal leakage. Aims and Objectives: To evaluate the marginal leakage of three different obturating materials and techniques using stereomicroscope. Materials and Methods: Thirty freshly extracted maxillary anterior teeth were collected and were divided into three groups of 10 each for which the biomechanical preparation was done. The teeth were divided into three experimental groups according to the obturation material and technique used, Group I: gutta-percha with AH Plus root canal sealer (lateral condensation): Group II: thermoplasticized gutta-percha technique-non-carrier-based (calamus) with AH Plus sealer (backfill): Group III: C point (self-sealing root canal obturating system) with bioceramic sealer (single cone). Each specimen was subjected for testing apical sealing ability. The values of microleakage associated with different root canal sealers were evaluated using a stereomicroscope. Results: There was no statistically significant difference in the mean scores of apical dye penetration/leakage among all the three groups (P = 0.091), whereas Group I showed a higher degree of apical leakage than the other techniques tested. Conclusion: None of the tested filling materials provided a gap-free or void-free root canal filling; however, thermoplasticized gutta-percha is used with AH Plus sealer exhibited less voids and gaps when compared to other tested materials.

A Comparative Evaluation of Fracture Resistance of Endodontically Treated Teeth Using Different Post-Obturation Restorative Materials: An In Vitro Study.

This in vitro study was conducted to evaluate and compare the fracture resistance of endodontically treated teeth using different post-obturation restorative materials. Seventy-five non-carious extracted human teeth were collected. Access opening, chemicomechanical preparation, and obturation were done. Teeth were randomly divided into various groups depending on the type of post-endodontic restoration: group I-control group, group II-Tetric-N-Flow Bulk Fill, group III-Tetric-N-Flow Bulk Fill + everX Posterior, group IV-P60, and group V-P60 + everX Posterior. The fracture resistance of each sample was measured using the universal testing machine. Results: The results obtained were subjected to statistical analysis. This demonstrated that group III (Tetric-N-Flow Bulk Fill + everX Posterior) was shown to be the most effective group followed by group V (Filtek P60 + everX Posterior) out of all of the other restorative experimental groups. Conclusion: Tetric-N-Flow Bulk Fill + everX Posterior showed maximum fracture resistance among the experimental groups.

Microscopic Evaluation of Dentinal Defects after Root Canal Preparation with Different Hand and Nickel-Titanium Files; An In Vitro Study.

Background: Effective endodontic instrumentation aims to remove microorganisms, debris, and tissue from the root canal while maintaining dentinal integrity. This study compares dentinal defect incidence following canal preparation with different hand files, nickel-titanium rotary files, and reciprocating files. Materials and Methods: Eighty single-rooted mandibular premolars with mature apices were collected. Four groups (n = 20) were established based on canal patency establishment, canal preparation technique, irrigation solution, and final irrigation. After root sectioning at 3 mm, 6 mm, and 9 mm from the apex, slices were examined under a stereomicroscope, and dentinal defects were recorded. A second examiner reviewed the images. Results: The results showed significant difference of P = 0.031 among Hand files vs. Rotary ProTaper files: In Hand files vs. Reciprocating WaveOne files significant difference was P = 0.048, and for rotary ProTaper files vs. Reciprocating WaveOne files: No significant difference (P = 0.643). Dentinal defect counts were similar at 3 mm, 6 mm, and 9 mm. Statistically significant variation was observed between hand files and rotary files, as well as hand files and reciprocating files. Conclusion: Both rotary and reciprocating files showed a statistically significant increase in dentinal defect incidence compared to hand files. However, clinical implications should be considered cautiously. Instrumentation technique selection should be based on clinical context, operator experience, and patient factors. Further clinical studies are needed for validation.

Compare the Centering Ability, Canal Transportation and Root Canal Area Increase of XP Endoshaper, Hyflex CM and K3 XF File System by using Cone Beam: An Original Research.

Objective: Using cone beam computed tomography (CBCT), this study compared three rotary file systems-XP Endoshaper, Hyflex CM, and K3 XF-for centering, canal transportation, and root canal area growth. Materials and Methods: The rotating file system randomly separated 60 removed human mandibular molars into three groups (n = 20). Manufacturer-recommended root canal instrumentation was done. Specialized software examined pre- and post-instrumentation CBCT scans. Centering ability was measured by canal transportation and root canal area expansion at different levels from the apex. Results: The Hyflex CM file system had the best centering and the least canal transit at all levels (P < 0.05). XP Endoshaper increased the root canal area the most (P < 0.05). The K3 XF file system had average centering and canal transfer results. Conclusion: The Hyflex CM system centered well, whereas the XP Endoshaper system increased the root canal area the most. The clinical context and therapeutic goals should determine the rotating file system.

Comparative Analysis of the Efficacy of Various Retreatment File Systems in the Removal of Gutta-Percha in Retreatment Cases and Time Taken During the Procedure: An In Vitro Cone Beam CT Study.

Background Removing gutta-percha manually can be a challenging task, especially when addressing densely packed root-filling material, particularly in cases where resin-based sealers are employed for obturation. The use of nickel-titanium (NiTi) rotary instruments not only effectively shapes the root canal but also efficiently removes the endodontic filling from the curved canal during retreatment. Hence, incorporating rotary NiTi instruments in retreatment cases can alleviate fatigue for both patients and operators. Objectives This study aims to compare the efficacy of Neo-Endo retreatment files, R-Endo retreatment files, and K and H files in the removal of endodontic filling material. Additionally, the remnants of gutta-percha in root canals are evaluated using cone beam computed tomography (CBCT). Materials and methods A total of 60 extracted first maxillary molar teeth were selected for this study. Canal preparation was conducted using the step-back method up to an apical size of 40 K-file. The obturation process involved the use of gutta-percha points and AH Plus sealer in a lateral compaction technique. Post-operative CBCT scans were taken. The samples were randomly divided according to the retreatment files used: group I included Neo-Endo retreatment files, group II included R-Endo retreatment files, and group III included conventional K-files and Hedstroem files (H-Files). The retreatment procedure was considered complete when the last instrument easily reached the working-length range and was physically clean. A stopwatch was used to record the time taken by each file to remove the obturating material. T1 represented the total time (including irrigation and change of file) required to reach the apex, while T2 indicated the complete removal of materials from the canal with the last instrument. The overall time recorded (TT) was calculated as T1 + T2. The removal process was analyzed with CBCT scans. Results The Neo-Endo retreatment files removed the filling materials better and more quickly than the other files. Conclusions Despite the presence of residual filling material in all samples, the Neo-Endo retreatment files left the least amount of residual filling material and achieved the shortest completion time.

Influence of Passive Ultrasonic Irrigation of the Photosensitizer Used in Photodynamic Therapy on Microbial Reduction in the Root Canal System: An in Vitro Study.

Introduction: The success of endodontic treatment is based on microbial reduction promoted by the interaction of chemical and mechanical procedures. Photodynamic therapy (PDT) is used as an adjunct to conventional treatment, with significant microbial reduction. This study aimed to evaluate the influence of passive ultrasonic irrigation (PUI) of the photosensitizer (PS) used in PDT on microbial reduction in the root canal system. Materials and Methods: Forty-five mesiobuccal root canals from extracted human mandibular molars that were inoculated with standard strains of Enterococcus faecalis, Candida albicans, and Streptococcus mutans for 21 days were selected. The root canals were prepared using the ProTaper Next system and randomly divided into 3 groups (n=15): 1) PDT: PDT alone; 2) PUI+PDT: PUI followed by PDT; and 3) PUI/PS+PDT: PUI of the PS followed by PDT. Microbiological samples were collected from the canals before and after using the protocols described above. The data were analyzed by analysis of variance (Tukey's test) at a significance level of 5%. Results: Microbial counts before PDT, PUI+PDT, and PUI/PS+PDT did not differ significantly (P>0.05), showing methodological standardization in the microbial contamination of the root canal system. There was a significant reduction in microbial counts after PDT (61.05%), PUI+PDT (65.04%), and PUI/PS+PDT (68.58%) (P<0.01), but with no statistically significant difference between the three groups (P>0.05). Conclusion: Based on the present findings, it was concluded that the combination of PUI with PDT or PS activation did not influence microbial reduction achieved by PDT alone.

Filling Material Bond Strength to Dentin Is Positively Influenced by the Agitation of Endodontic Final Irrigating Solutions.

Introduction: The final step of irrigation has been considered to of increase the bonding strength of filling material to dentin. This study investigated the impact of three final-step irrigation methods on the endodontic sealer bond strength to dentin by using a micro push-out test. Materials and Methods: Palatal roots of human maxillary molars were cleaned and shaped and randomly divided in six groups (n=15) according to the final-step irrigation method and the type of root canal sealer used. The solutions used for the final-step irrigation were 17% ethylenediaminetetraacetic acid and 2.5% sodium hypochlorite, which underwent three methods: 1) syringe-needle irrigation/conventional, 2) passive ultrasonic irrigation, and 3) XP-endo Finisher agitation. The root canal sealers used were: EndoSequence BC Sealer, and AH-Plus sealer. Roots were obturated with the single cone technique and then, cross-sectioned in 2-mm-thick slices (3 slices from each root). Push-out test was performed on the sliced specimens (cervical, middle, and apical thirds) with a universal testing machine. Bond strength values were recorded in megapascal (MPa). Subsequently, each specimen was longitudinally split to verify the type of failure. Data analysis was performed using Johnson transformation, three-way analysis of variance, Tukey's post-hoc tests, and the partial Eta squared test. Results: There were significant differences in bond strength between the sealers [AH: 4.46±2.24 and BC: 3.47±2.19 MPa (P<0.001)]; between final-step irrigation methods [passive ultrasonic irrigation: 4.52±2.25, XP-endo Finisher: 3.93±3.93 and syringe-needle irrigation/conventional: 3.37±2.51 MPa (P<0.001)], and between the root canal thirds represented by the sliced specimens [cervical: 5.45±2.39, middle: 4.14±1.99 and apical: 2.30±1.30 MPa (P<0.001)]. The interaction between the variables had no significance (P>0.05). Conclusion: Agitation of the final irrigating solution may improve the bonding of the sealer to canal walls. AH-Plus sealer had the highest bond strength. The bond strength reduced significantly towards the apical third.