Root Canal Shaping Research Articles

Contemporary Applications and Future Perspectives of Robots in Endodontics: A Scoping Review.

In the era of modern advanced endodontics, the reduction of reliance on human hands and shifting towards robotics could benefit the precision and accuracy of endodontic treatment. This scoping review aims to describe current and emerging trends in the applications of robots in endodontics and highlight their limitations and future perspectives. This review followed the PRISMA Extension for Scoping Reviews (PRISMA-ScR) standards. A comprehensive search of internet databases was conducted until February 2024. Studies that specifically examined robots in the field of endodontics were included. The studies focused on root canal cleaning, shaping, surgical procedures, and other applications. Robotic systems demonstrated improved accuracy, precision, reduced errors, and time savings compared with manual techniques. Robotics in endodontics show promise, especially in surgical procedures, with AI integration enhancing accuracy and efficiency. Challenges such as cost, physical limitations, and absence of tactile feedback require further research and investment.

To Compare and Evaluate Rotary and Manual Techniques in Biomechanical Preparation of Primary Molars to Know Their Effects in Terms of Cleaning and Shaping Efficacy.

The introduction of the rotary file system for children was a revolution in the field of pediatric endodontics. These files are cost-effective and help in consistent obturations with shorter instrumentation time. The present randomized controlled trial (RCT) was planned for a comparative evaluation of rotary and manual techniques in biomechanical preparation of primary molars to determine their effect in terms of cleaning and shaping efficacy, working time, quality of obturation, and postoperative pain. A randomized clinical trial study was conducted in 75 children aged 5-9 years requiring pulpectomy. Each tooth was randomly assigned to one of the three treatment groups: Kedo-S files, rotary K-Flex files, and hand instruments group. It was observed that Kedo-S files and rotary K-Flex files were more effective in cleaning and shaping of root canals compared to hand H/K files. The postbacterial count for hand files was higher compared to rotary files. Shorter working time was seen with rotary files (3.88-5.04 minutes) compared to hand files (15.68 minutes). Rotary files showed a reduced number of voids, with Kedo-S files in 92% of cases and rotary K-Flex files in 80% of cases. Apical seal and extent of fill were maximum with rotary files, having a grade C rating in 92% of cases. Kedo-S files and rotary K-Flex files showed a significant reduction in postoperative pain compared to hand files. The present study showed a significant reduction in bacterial count, working time, quality of obturation, and postoperative pain with rotary files. Moudgalya MS, Tyagi P, Tiwari S, et al. To Compare and Evaluate Rotary and Manual Techniques in Biomechanical Preparation of Primary Molars to Know Their Effects in Terms of Cleaning and Shaping Efficacy. Int J Clin Pediatr Dent 2024;17(8):864-870.

Comparative Evaluation of Dentinal Microcrack Formation During Root Canal Preparation Using Different Rotary Files: An In Vitro Study

Background:The success of endodontic treatment depends on completely removing all vital and necrotic pulp tissue, microorganisms, and microbial toxins from the root canal. During the cleaning and shaping process, the canal is shaped through the interaction between instruments and the dentin walls. These interactions can create several temporary stress points within the dentin, which may lead to the development of dentinal defects, craze lines, or microcracks. As a result, the techniques employed for shaping root canals carry the risk of starting crack formation, which, under functional pressure, could progress into complete fractures. This study was aimed to compare and evaluate the incidence of dentinal microcrack formation during root canal preparation using ProTaper Universal, ProTaper Gold, NeoEndo Flex and Hyflex EDM files. Materials and Methods: A total of 95 freshly extracted single rooted premolars with single straight canal were selected and stored in normal saline. Each specimen was examined using dental operating microscope to exclude cracked samples. Specimens then decoronated using a diamond disc and water as a coolant to a standardized length of 14 mm. Canal patency was determined by passing 10 K file passively and the working length was established 1 mm short of the file length at which the file become visible at the apical foramen. Canal was then enlarged upto15 k size file. Teeth samples were then divided into 5 groups having 19 teeth each. Group 1: Control Group (Uninstrumented teeth), Group 2 : Protaper Universal, Group 3 : Protaper Gold, Group 4 : NeoEndo Flex ,Group 5 : Hyflex EDM. After completion of cleaning and shaping procedure (to a standard apical diameter of 25), canal was rinsed with distilled water. Root was then horizontally sectioned at 3 mm, 6 mm and 9 mm from the apex with diamond disc at low speed under water cooling. All the sections were evaluated under stereomicroscope for presence of cracks and images were recorded. Cracks were observed as lines extending from the root canal lumen to the dentin or from the outer surface into the dentin. Results: All the file systems used in this study showed dentinal microcracks. ProTaper Universal exhibited the highest percentage of dentinal defects, while Hyflex EDM displayed the lowest among the file systems used (ProTaper Universal, ProTaper Gold, NeoEndo Flex and Hyflex EDM). The defects were present more in the apical third (3 mm) as compared to 6 mm (middle third) and 9 mm (coronal third) sections

Root canal transportation with ProTaper Next and WaveOne Gold: A systematic review

Root canal transportation is a significant concern in endodontic therapy, impacting treatment outcomes. ProTaper Next (PTN) and WaveOne Gold (WOG) are popular endodontic instrumentation systems used to shape root canals. This systematic review aimed to evaluate the literature on root canal transport with PTN and WOG. Fourteen studies were analyzed, highlighting the overall effectiveness of both systems. The PTN showed potential advantages in minimizing canal transport, while the WOG preserved the original canal shape. Operator experience and canal curvature influence performance. This review provides evidence-based insights to aid endodontic practitioners in making informed decisions for successful root canal treatments. The aim of this systematic review was to evaluate and synthesize the literature on root canal transportation with ProTaper Next (PTN) and WaveOne Gold (WOG) instrumentation systems in endodontic therapy. A comprehensive literature search was conducted using the PubMed Central, Scopus, EBSCO, Embase and Web of Science databases from 2000 to 2022. Studies that met the predefined inclusion and exclusion criteria were selected for analysis. Data on study design, participant characteristics, intervention details, comparison groups, outcomes, and results were extracted from the included studies. The methodological quality of the studies was assessed using appropriate tools, and the findings were synthesized qualitatively. A total of 14 studies were included in the systematic review. The analysis revealed that both the PTN and WOG systems demonstrated overall effectiveness in root canal preparation. PTN rotary files performed adequately with inexperienced operators and showed potential advantages in minimizing canal transportation. On the other hand, WOG files exhibited a conservative approach, preserving the original canal shape. However, variations in performance were observed depending on the instrumentation method, operator experience, and canal curvature. This systematic review provides valuable insights into the ability of the PTN and WOG to manage root canal transport. Both systems demonstrated satisfactory outcomes, with WOG often preserving the natural canal anatomy. The findings suggest that proper operator training and technique play vital roles in achieving optimal results. Clinicians should consider the unique characteristics of each system when selecting instrumentation for root canal treatments. Nonetheless, it is crucial to acknowledge the limitations of the included studies, such as variations in sample sizes and operator experience, which may impact the interpretability of the findings. Future research should address these limitations and further explore the efficacy of these instrumentation systems in various clinical settings. The evidence derived from this systematic review can aid endodontic practitioners in making evidence-based decisions for successful root canal procedures.

Knowledge, awareness, and approaches of dentistry students about separated instruments in root canals: A cross-sectional study.

This survey aims to assess the understanding, viewpoints, and methods employed by undergraduate dental students in the fourth and fifth grades regarding broken endodontic instruments in root canal procedures. A survey comprising 27 questions across three sections-demographic information, practical application, and knowledge-approach-awareness inquiries-was developed. It was distributed to 282 students either in person or via a link shared through WhatsApp groups using Google Forms. Out of the total 219 respondents (77.6%), 10.6% experienced instrument breakage once during their clinical internship, while 2.8% encountered it more than once. The majority (86.7%) did not face instrument fracture incidents. Among these occurrences, it was observed that endodontic instruments were most commonly separated in molars, accounting for 51.9%. Nearly half (48.1%) of the students noted instrument breakage during the initial attempt to reach the apical part of the canal, while 55.6% reported breakage during root canal cleaning and shaping. Most dental students opted to leave the separated instrument in the root canal and proceed with filling it. Enhancing students' understanding and awareness of this matter will help prevent potential complications and enable them to handle such situations appropriately when they arise.

Endodontic irrigants from a comprehensive perspective.

This review article explores the fundamental principles of modern endodontics with a focus on root canal cleaning and shaping. It reviews commonly used endodontic irrigant, namely sodium hypochlorite (NaOCl), herbal extracts, chlorhexidine (CHX), and chelating agents, highlighting their properties, applications, and potential drawbacks. NaOCl, a key antimicrobial agent, demonstrates effectiveness against various microorganisms but poses challenges such as high cytotoxicity. Herbal extracts, gaining recognition in endodontics, present an alternative with potential advantages in preserving dentin integrity. CHX, known for its broad-spectrum antimicrobial activity, is discussed in both liquid and gel formulations, emphasizing its role in reducing smear layer formation and preserving hybrid layer durability. Chelating agents, specifically ethylenediaminetetraacetic acid and citric acid, play a vital role in removing the smear layer, enhancing dentin permeability, and facilitating the penetration of antimicrobial agents. The review article underscores the importance of careful application and consideration of each irrigant's properties to ensure safe and effective endodontic procedures. It serves as a valuable guide for clinicians in selecting appropriate irrigants based on specific treatment requirements.

A review of tissue engineering in regenerative endodontic treatment

Background: Regenerative endodontic treatments are classified based on approach in the procedures and principles. One is cell-free approach that involves a revitalization procedure to achieve continued root growth while the other is cell-based approach which involves pulp/dentin regeneration through isolation and ex vivo expansion of stem cells seeded in the scaffold and then transplanted into the canal space. Technically, the cell-free approach is simpler than cell-based approach because the former does not concern about external stem cell isolation and culture. Currently, the gold standard and the one that has been clinically performed is cell-free approach. Cell-based approach is still not a standard because currently the cell-based approach is still in the clinical trial stage. Purpose: to evaluate the biological basis and clinical protocols recently used in regenerative endodontic treatment and discuss potentially future treatment approaches. Review: The literature review was searched in PUBMED with the keywords: immature permanent teeth, pulp revascularization, stem cells and regenerative endodontics. The regenerative endodontic treatments with various procedures and techniques result in a significant increase in root length and dentinal wall thickness. Stimulation of stem cells in apical root canal system is required to induce tissue formation and continued root maturation. Conclusion: The success of regenerative endodontic therapy relies on the development of a technique that enables clinicians to create functional pulp tissue within cleaned and shaped root canal systems. It is hoped that further research studies are required to define advantages and limitations of cell-free and cell-based approach.

Assessment of Vertical Force Generated with Single File Systems during Shaping of Constricted Root Canals.

This study aimed to evaluate the shaping force generated with OneShape (OS) and HyFlex EDM (HEDM) systems designed for single file shaping, in comparison with ProTaper Next (PTN). Maxillary premolar teeth received access cavity preparation and their canals were shaped with OS, HEDM, or PTN to size 25 according to manufacturer's instructions with consistent pressure on the files to give a gentle "in-and-out" movements of 2 mm amplitude. The canal shaping was completed with a total of three insertions. After each insertion, 1% NaOCl irrigation and recapitulation with K-file size 15 were performed. The vertical shaping force was measured using a force gauge (M5-20 Advanced Digital Force Gauge; Mark-10 Corporation, NY). The shaping time was analyzed by using a one-way analysis of variance (ANOVA) test and differences between the mean apical and coronal maximum force values were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. The level of significance was set as 0.05. The magnitude of the vertical forces increased with successive advancements of the instruments within the canal. During canal shaping procedures in all groups, the apical and coronal maximum force values of the OS and HEDM ranged from 2.5 to 7.2 N and 1.3 to 2.9 N, respectively. PTN generated the lowest maximum apical forces during the second and third insertions (p < 0.05). HEDM generated significantly less maximum coronal forces than both OS and PTN during the first insertion while the use of OS was associated with the highest amount of force values in the second and third insertions (p < 0.05). In terms of shaping time, no significant differences were detected among the three tested systems (p = 0.606). The tested single file systems were associated with higher shaping forces in the apical direction that were significant in the second and third insertions.

Adhesive Strength of Glass Fiber-Reinforced Posts with Silane Conditioning Versus Universal Adhesive System Conditioning: An In Vitro Study

Abstract Aim: The current study compared the push-out adhesive strength of glass fiber-reinforced posts with a silane-treated surface versus a universally adhesive-treated surface. In both cases, a universal self-adhesive cement was used. Materials and Methods: Thirty bovine teeth were used in an in vitro experiment. Through cutting, the root and coronal sections were divided. Subsequently, the manufacturer’s recommendations were followed for the placement of glass fiber-reinforced posts through root canal therapy, gutta-percha removal, and canal shaping. On the basis of how the posts were treated prior to cementation, the samples were split into three groups (n = 10). Posts in group A (control) did not get any prior treatment. Posts in group B had previously received a silane treatment. Posts in Group C had previously been coated with universal adhesive. Following the application of RelyX Ultimate universal self-adhesive cementation, the samples were segmented and subjected to a Push-Out test at a speed of 1 mm/min on a universal testing apparatus. Intergroup ANOVA was used to evaluate the adhesive strength means (measured in MPa), and Tukey’s post hoc test was performed afterward, with a significance level of P &lt; 0.05. Results: Compared to the glass fiber-reinforced posts pre-treated with silane (P = 0.003) and the control group (P &lt; 0.001), the adhesive strength of the posts pre-treated with universal adhesive was significantly higher. Similarly, the adhesive strength of the glass fiber-reinforced posts that had been pre-treated with silane was considerably higher than that of the control group (P = 0.012). Conclusion: Posts reinforced with glass fiber and pre-treated with universal adhesive exhibited notably greater adhesive strength compared to those pre-treated with silane. When compared to utilizing universal self-adhesive cement without pre-treatment, both pre-treatment techniques greatly increased the adhesive strength of glass fiber-reinforced posts.

Does Root Canal Shaping Effect the Accuracy of Electronic Apex Locators in Curved and Straight Root Canals?

Objective: To assess the influence of root canal preparation (RCP) on the precision of electronic apex locators (EALs) in both straight and curved root canals. Methods: The experimental setup included forty-two extracted human mandibular molars featuring both straight distal canals (0-10 degrees) and curved mesial root canals (30-50 degrees). Initial working length (AWL1) measurements were conducted under a stereomicroscope at X15 magnification prior to root canal preparation (RCP). Subsequently, electronic working length (EWL1) was determined using two different electronic apex locators (EALs) – Propex-Pixi and EndoRadar. RCP was carried out with ProTaper Ultimate F1, F2 files in mesial canals, and F1, F2, F3 files in distal straight root canals. The RCP procedure involved the implementation of a standard irrigation protocol along with the use of a sonic device for activation. Following RCP, measurements were repeated under a stereomicroscope and documented as AWL2. EWL measurements were also repeated and recorded as EWL2 after the preparation. The variation was calculated by subtracting AWL from EWL for each tooth (EWL1-AWL1 and EWL2-AWL2). Statistical analysis employed Paired Sample t-test and Wilcoxon tests. Results: There was no statistically significant difference observed in the accuracy of Propex-Pixi and EndoRadar Pro before and after root canal preparation for both straight and curved canals. Conclusion: Root canal preparation did not alter the accuracy of the electronic apex locators (EALs) used in this study, whether applied to curved or straight root canals.

Comparison of the effectiveness of the endodontic treatment using Reciproc Blue instrument with or without glide path preparation

Background: To overcome file fracture due to torsional stress and cyclic fatigue during root canal preparation, the Reciproc Blue endodontic file system with reciprocating motion helps to shape the canal with only one instrument. Objective: To compare the time of root canal shaping and the results of endodontic treatment of first molars with Reciproc Blue files with and without glide path preparation. Materials and Methods: A controlled clinical trial on 78 first molars with irreversible pulpitis in patients visiting Hue University of Medicine and Pharmacy Hospital from July 2020 to October 2022. Group 1 and Group 2 (n = 36 each) were respectively prepared with a Reciproc Blue file with and without a glide path preparation. Comparison of preparation time and treatment outcome based on clinical and radiographic characteristics at 1 week, 3 months, and 6 months. Results: Endodontic treatment using Reciproc Blue file without glide path preparation recorded a shorter time consumption (p &lt; 0.05) and no complications. However, the treatment results after 1 week, 3 months, and 6 months were not different between the two groups regards to glide path preparation (p &gt; 0.05). Conclusion: Shaping root canals with Reciproc Blue without creating a glide path reduces shaping time, simplifies the procedure, and does not adversely affect treatment outcomes compared to the group with glide path creation. Key words: First molar, glide path, Reciproc Blue, root canal preparation.

Assessment of microbial reduction following rapid chair-side sterilization of contaminated endodontic files

Background. Endodontic treatment is carry out in order to preserve a tooth whose pulp has been damaged where the injury extends to the peri-radicular tissue. The endodontic treatment is cleaning, disinfection of the root canal space and shaping it, followed by the obturation of the root canal system. The presence and re-entry of microbes inside the canal is the main reason for post-treatment infections, which is considered as an endodontic failure. Therefore, disinfection throughout the treatment is very important. The aims of the study were to find microbial growth on brand sealed endodontic files, taken directly from the manufacture's packages, compare between different chemical compounds in rapid sterilization of contaminated endodontic files and determine the most effective chemical method in the sterilization. Methods. The present study was performed to compare between different chemical compounds: 3% sodium hypochlorite, dendroid, chloroX and saline as the positive control in rapid sterilization of endodontic files in root canal treatment in dental practice using sealed endodontic files, taken directly from the manufacture's packages and sterile K-files sterilize by autoclaving. Results. The results of this study, concerning E. coli bacteria, indicated that Dentroid scored the best results (90% free of any E. coli bacteria), followed by CHX (20% free of E. coli bacteria), then 3% NaOCL (10% free of E. coli bacteria). The results, concerning S. aureus, showed that normal saline and 3% NaOCL scored the highest contamination percentages (100%). While least and equal distribution of CHX and dentroid (90% free of S. Aureus). Conclusion. The disinfecting solutions as CHX and Dentroid could be used as a method of rapid chair-side sterilization in clinical practice.

The effect of root canal preparation tapers on planktonic bacteria and biofilm reduction in the apical third: A correlative microtomography and microbiological laboratory study.

To evaluate the influence of different preparation tapers on the reduction in planktonic bacteria and biofilms of Enterococcus faecalis and Candida albicans in the apical third (4 mm) of the mesial roots of mandibular molars, correlating decontamination with canal shape. After microtomography analysis for morphological standardization of the canals, 48 mandibular molar roots, each containing two canals (96 canals), were contaminated with E. faecalis and C. albicans and divided into four groups (n = 11) for canal instrumentation using ProDesign Logic 2 files with different tapers G (.03): # 25.03; G (.04): # 25.04; G (.05): # 25.05; and G (.06): # 25.06 and irrigation with 2.5% sodium hypochlorite. Four roots were examined under a scanning electron microscope (SEM) to qualitatively assess biofilm formation. Eight roots were used as the negative control group (samples were not contaminated). Bacteriological samples were taken exclusively from the apical third of the roots before and after chemical-mechanical preparation and bacterial counts were determined (CFU/mL). The final micro-CT scan was used to quantify the volume variation and unprepared canal area in the apical third. Statistical analysis was performed using the Kruskal-Wallis, Student-Newman-Keuls and Wilcoxon tests for analysis of microbiological data. anova and the Tukey or Games-Howell test were used for analysis of micro-CT data and Spearman's test for correlations (α = 5%). All groups showed a significant reduction in bacteria (p < .05), with no statistically significant difference between groups. There was no significant difference in per cent volume increase between groups. The unprepared area (Δ%) was affected by the file used (p = .026) and was significantly lower for G (.06) compared to G (.03). There was no statistically significant correlation among bacterial reduction, volume and unprepared area (p > .05). The different preparation tapers influenced root canal shaping in the apical third but did not improve decontamination in this region.

Preventive Effects of Laser Irradiation and Dentin Bonding Agent Application on Tooth Discoloration Induced by Mineral Trioxide Aggregate

The aim of the present study was to evaluate the effect of the pre-application of dentin bonding agent and laser application on the prevention of tooth discoloration caused by (MTA) in the presence of blood. Fifty extracted human anterior teeth were prepared by standardizing root lengths to 10 mm and shaping root canals. Specimens were divided into five groups (n = 10) based on the treatment applied to the pulp chamber dentin wall: Group 1/no surface treatment; Group 2/Optibond FL; Group 3/Clearfil SE; Group 4/Optibond Universal adhesive application; Group 5/Nd:YAG laser application. Root canals were filled with fresh human blood below the cemento-enamel junction (CEJ), followed by ProRoot MTA, and collagen barrier placement. Color changes were monitored using a spectrophotometer at 0, 7, 30, 90, and 180 days post MTA placement. Color differences (∆E) were calculated and analyzed using two-factor mixed-design ANOVA with Sidak adjustment at p = 0.05. The degree of coloration increased with time within each group (p &lt; 0.05). No significant differences were observed between Optibond FL and Optibond Universal within each time interval, or between Clearfill SE Bond and the control group (p &gt; 0.05). When compared to the control group, the Nd YAG group exhibited the least degree of discoloration in all time intervals (p &lt; 0.05). Although the Nd:YAG laser had promising results, none of the methods can guarantee a 100% prevention of discoloration resulting from tooth discoloration caused by MTA-blood contact.

Cone-Beam Computed Tomography Analysis of the Root Canal Morphology of Lower Second Molars in the Croatian Subpopulation

The aim of this study was to investigate the root canal morphology of lower second molars in the Croatian subpopulation of the Zagreb region using cone-beam computed tomography (CBCT). We analyzed 3212 CBCT scans from the two radiology centers in Zagreb. The number of roots and root canals, the occurrence of C-shaped canals and additional roots were recorded. “C”-shaped roots were classified according to Melton classification. Canals in the mesial root were classified according to Vertucci. Lower second molars were found on 608 CBCT scans from a total number of 859. Among them, 78 (9.1%) had a “C”-shaped form. In the mesial roots, the frequencies of Vertucci types were: Type I in ninety-four cases (12.0%), Type II in three hundred and twenty cases (41.0%), Type III in six cases (0.8%), Type IV in three hundred and fifty-two cases (45.1%), Type V in three cases (0.4%), Type VI was found in four cases (0.5%) and Type VIII was found in one case (0.1%). Radix entomolaris and paramolaris were found in 29 (3.4%) lower second molars. The lower second molars in the Zagreb population show significant diversity in internal anatomy with a relatively high prevalence of “C”-shaped root canals and merged root canals in the mesial root.

An in vitro evaluation of dentinal microcrack formation during root canal preparations by three different nickel–titanium systems: ProTaper Gold, HyFlex CM, and Silk

Aim: This study aimed to compare the frequency of dentinal microcracks after root canal shaping with three different nickel–titanium (NiTi) systems, namely, ProTaper Gold (PG), HyFlex CM (HCM), and Silk. Methods: One hundred mandibular premolars with a single canal were chosen for this study. All specimens were decoronated and divided into four groups of 25 each. Teeth were mounted in the acrylic block with simulated periodontal ligaments. Group I served as a negative control Group, in which no treatment was performed. Biomechanical preparation was done in the Group II, using the Protaper gold file system. Group III, using the Hyflex CM file system and Group IV, using the Silk file system. Specimens were horizontally sectioned at 3, 6, and 9 mm from the apex using the low-speed diamond disc under water cooling. The slices were then viewed under a stereomicroscope at ×25 to determine the presence of cracks. The absence or presence of cracks was recorded, and the data were analyzed with a Chi-square test. The significance level was set at P &lt; 0.05. Results: Coronal section showed lesser crack formation in all three groups after biomechanical preparation. More number of dentinal microcracks were seen in the apical sections, followed by the middle and the coronal sections in Group II (PG), followed by Group IV (Silk), and Group III (HCM), respectively. Group II showed more microcracks at all three levels of the root canals when compared with Groups III and IV. Intergroup analysis showed no statistically significant difference in microcrack formation. Conclusion: Within the limitation of this in vitro study, it can be concluded that NiTi instruments may cause cracks on the root surface. HCM and Silk files tend to produce a less number of cracks as compared to PG instruments.

Evaluation of the stress generated during biomechanical preparation with nickel–titanium rotary endodontic file using finite element analysis

Introduction: Adequate biomechanical preparation of root canals is the essence of successful endodontic therapy. Roots with curved canal framework led to endodontic complexity. The hassles in the preparation of such complex canals have prompted the inauguration of nickel–titanium (Ni-Ti) instruments with properties of shape memory and superelasticity. They benefit root canal preparation with causing less aberration, yet intracanal separation due to fatigue remains a concern. The study was intended to evaluate and compare the stresses developed during biomechanical preparation with Ni-Ti rotary file in straight, moderate, and severely curved root canals using finite element analysis (FEA). Materials and Methods: Six real sizes, three-dimensional root models were designed in SolidWorks software with varying angles of curvature (2°–45°), and using the same software, ProTaper Gold F2 rotary file was developed. All the designed root models with the rotary file inserted into each model were subjected to FEA. ANSYS Software (version 17.2 Company, Commonwealth of Pennsylvania, USA) 2015 was used to simulating root canal shaping, and the stresses generated in all the root canal models were observed. Results: Highest mean stress was observed with 45° models which was 235.95 MPa, followed by a 30° simulated model showed 220.36 MPa and least stress of 125.22 MPa was observed with 2° models (P &gt; 0.05). Conclusions: Increased canal curvature has definitely resulted in generation of more amount of stress.

Using manual versus mechanized glide path instruments and ProTaper Gold versus ProTaper Next systems in curved canals: micro-CT study.

The aim of this study was to evaluate the root canal shaping effect of ProTaper Gold (PTG) versus ProTaper Next (PTN) instrumentation systems, and of a manual #15 K-type file (K15) versus the ProGlider (PG) mechanized instrument for glide path creation, in severely curved mesial canals. Twenty-four mandibular molars with two separate mesial canals were anatomically matched using computed tomographic scanning, and then divided into two groups (n=12) according to the glide path instrument used, either K15 or PG. In all teeth, the PTG system was used to prepare the mesiobuccal canal, and the PTN, the mesiolingual canal. The teeth were scanned by computed microtomography, before and after root canal preparation, and the values of the initial volume, final volume, volumetric variation, untouched walls, and canal transportation variables were determined. The data were analyzed using the two-way ANOVA test, and the Tukey test for multiple comparisons. There was no significant difference among the study groups regarding volumetric variation or root canal transportation, either in the cervical, middle or apical thirds, or in the entire root canal (p>0.05). In the apical third, the percentage of untouched walls was significantly higher in groups using K15 than in those using PG (p<0.05), namely 33.144% and 23.285%, respectively, irrespective of the instrumentation system. In the other regions, there was no difference between K15 and PG regarding this variable. It was concluded that PG was associated with a lower rate of untouched walls in the apical region than K15.

Effect of T ect of Triple Antibiotic P riple Antibiotic Paste, Double Antibiotic P aste, Double Antibiotic Paste, and aste, and Calcium Hy Calcium Hydroxide on Antibiotic Resistance of T xide on Antibiotic Resistance of Tet Repr et Repressor Proteins, T oteins, Tetracycline Resistance Gene W cline Resistance Gene W, and T , and Tetracycline Resistance Gene Q: A Randomized

Objective: To investigate the effect of the use of Calcium Hydroxide (Ca(OH)2 ), Triple Antibiotic Paste (TAP), and Double Antibiotic Paste (DAP) as intra-canal medicaments on the development of antibiotic resistance by evaluating tetracycline genes. Methods: Forty five patients were randomly assigned into 3 groups according to the intracanal medication using a web program (www.randomizer.org), (Ca(OH)2 , TAP and DAP). Root canal bacteriological samples were collected before root canal treatment (S1) and after chemo-mechanical procedures (S2). Following root canal shaping procedures, intra-canal medication of the root canals was performed with selected intra-canal medicament. A second appointment was planned for the patients 15 days later. At the second appointment, the medication was removed mechanically and after irrigation of the root canals, the post medication samples (S3) were collected. Bacteriological samples were then investigated for bacterial counts and antibioticresistant genes [Tet Repressor proteins (TetR), Tetracycline resistance gene W (TetW) and Tetracycline resistance gene Q (TetQ)] using polymerase chain reaction (PCR), and the data were statistically analyzed. The Friedman, Kruskall-Wallis and chi-square tests were used. These genes were selected as the difference between TAP and DAP is that TAP contains tetracycline and tetracycline resistance is governed by tet genes. Results: There was no statistically significant difference among the samples (S1, S2, and S3) in terms of the number of root canals positive for antibiotic resistance genes in both the Ca(OH)2 and DAP groups. However, the number of root canals positive for TetR gene increased significantly (6 [40%] to 12 [86%]) following intra-canal medication with TAP. Conclusion: It can be concluded that 15 of days intra-canal medication with TAP causes tetracycline resistance. In contrast, DAP does not cause tetracycline resistance and it has similar antibacterial effectiveness to TAP. The DAP would be the choice of medicament rather than TAP in clinical practice.

Postoperative pain of single-visit endodontic treatment with gutta-percha versus MTA filling: a randomized superiority trial

BackgroundPostoperative pain has remained a challenge for clinicians. This randomized superiority trial compared the levels of postoperative pain following the use of gutta-percha (GP) and sealer or mineral trioxide aggregate (MTA) as root canal filling materials in teeth with asymptomatic apical periodontitis.MethodsA total of 119 patients were initially evaluated in this two-arm, parallel-group, single-blind, superiority randomized trial. The inclusion criteria were participants aged 18–65 years with single-canal premolars diagnosed with asymptomatic apical periodontitis. The participants were finally divided into two groups using the permuted block randomization method. In the GP group (N = 46), the cleaned and shaped root canals were filled with gutta-percha and AH Plus sealer, while in the MTA group (N = 48), the cleaned and shaped root canals were filled with an MTA apical filling and a coronal gutta-percha and sealer. Patient pain level was measured 6, 12, 24, 48, and 72 h postoperatively using a 10-point visual analog scale (VAS). The data were analyzed by the chi-square, independent t, Friedman, and Mann-Whitney U tests.ResultsThe mean of VAS scores decreased significantly over time in both groups (P < 0.001). The mean VAS scores were significantly lower in the MTA filling group than in the other group (P < 0.05). Female patients reported higher VAS scores at 6- and 12-hour periods in both groups (P < 0.05).ConclusionMTA as a root canal filling material might be a valuable option for clinicians due to its low postoperative pain.Trial registrationThe trial protocol was registered at the Registry of Clinical Trials (IRCT20191104045331N1).