Canal Instrumentation Research Articles

The Effectiveness of Triton Used With XP-3D Adaptive Files and Active Irrigation on Smear Layer Removal During Root Canal Preparation: A Qualitative Scanning Electron Microscopy (SEM) Study.

Standard irrigating protocols during root canal treatment call for the use of sodium hypochlorite during chemo-mechanical preparation, followed by final irrigation with ethylenediaminetetraacetic acid (EDTA). This study determined the effectiveness of a new irrigant, Triton (Brasseler, USA), on smear layer removal during root canal treatment compared to that of 5.25% sodium hypochlorite and CanalPro EDTA 17% (Coltene). Twenty-one extracted anterior teeth were prepared for root canal treatment. The teeth were divided into three groups: five teeth were used as control with saline as the irrigant, eight teeth with sodium hypochlorite and 17% EDTA as irrigants, and eight teeth with Triton as the irrigant. Root canal preparation was done using the XP-3D shaper and finisher files (Brasseler, USA) for all teeth with respective irrigants. A single operator performed all root canal treatment procedures. The teeth were prepared for scanning electron microscopy (SEM), and analysis was performed by a second investigator. The smear layer removal was qualitatively assessed to determine the effectiveness of irrigants. Smear layer removal was most effective for teeth irrigated with 5.25% sodium hypochlorite, followed by 17% EDTA (Group B). Teeth irrigated with Triton (Group A) showed a similar appearance to the hypochlorite/EDTA group but with isolated instances of inter-tubular debris. Sodium hypochlorite use followed by a final rinse with EDTA remains the gold standard for the removal of the smear layer created during canal instrumentation.

Influence of operator's experience on the quality and success rate of root canal treatment with new nickel-titanium instruments

Objective: To analyze the influence of operator's experience on the quality and success rate of root canal treatment with new nickel-titanium instruments, providing support for improving the success rate of root canal treatment with new nickel-titanium instruments in clinic. Methods: Cases of root canal treatment and non-surgical root canal retreatment with 6-12 months recall performed by residents (resident group) with experience of 1-3 years and endodontic specialists (specialist group) with experience of 5-7 years were collected from the electronic medical system of the Department of Endodontics, School of Stomatology, Capital Medical University, from September 2020 to August 2021. All cases were prepared by engine-driven glide path files and controlled memory nickel-titanium finishing files. Chi-square test and logistic regression were used to analyze the differences and influencing factors of complications, filling quality and success rate of root canal treatment between the two groups. Results: A total of 277 cases performed by 24 residents and 3 specialists were included, 169 in the resident group and 108 in the specialist group. The clinical incidence of flare-ups was significantly higher in the resident group [3.6% (6/169)] than in the specialist group [0(0/108)] (P=0.048). There were no significant differences in ledges, root canal transportations, perforations, or instrument separations between the two groups (P>0.05). The prevalence of satisfactory fillings was 62.7% (106/169) in the resident group, which was significantly lower than that in the specialist group [86.1% (93/108)] (P<0.05). The success rate of root canal treatment was 91.7% (155/169) and 94.4% (102/108) in the resident group and the specialist group, respectively, with no significant differences (χ2=0.73,P=0.392). Multivariate analysis showed that the success rate of root canal treatment was related to complications and quality of root fillings (P<0.05). Conclusions: Higher success rate of root canal treatment could be achieved by residents and endodontic specialists with engine-driven glide path files and controlled memory nickel-titanium files.

In Vitro Research Methods Used to Evaluate Shaping Ability of Rotary Endodontic Files-A Literature Review.

In this article, we present a literature review of methods used to measure the shaping ability of endodontic rotary files, including the selection of endodontic sample type (extracted teeth versus simulated blocks) and an imaging evaluation method. This review was conducted as background research to identify concerns that arise when designing research studies in this domain and propose how the field can plan more systematic studies going forward. A literature search was conducted using PubMed, MEDLINE, Embase, ScienceDirect, Scopus, and e B-on databases, including studies published in English from January 2010 to June 2024. Only studies that specified in vitro or ex vivo methods for evaluating the endodontic performance of NiTi rotary files on canal transportation and centering ability were considered. A total of 86 studies met the inclusion criteria from an initial pool of 651. Of these, 67 studies used extracted teeth, while 20 utilized simulated root canals in resin blocks. For evaluation methods, 55 studies employed Micro-Computed Tomography and Cone-Beam Computed Tomography (MCT + CBCT), 30 used Double Digital Images/Radiographs/Photographs (DDIR + DDIP) with software analysis, 1 used both DDIR and MCT, 1 used high-precision nano-CT, and 1 used a digital single-lens reflex (DSLR) camera. The findings indicate that the MCT method and its advanced variations appear superior in many cases for evaluating the quality of root canal instrumentation due to their ability to provide detailed three-dimensional images. We also discuss the pros and cons of other evaluation methods, including CBCT and DDIR. Finally, we identify important factors to consider for optimizing future cross-study comparisons. This work highlights the importance of being familiar with shaping ability assessment methods as new instruments are introduced to the market.

Guided Endodontics in Calcified Canals: Literature Review

Endodontic treatment controls the root canal microbiota by shaping, disinfecting and filling the canals to promote periapical healing. The calcification process is linked to pulp alterations, usually caused by an inflammatory process due to caries, loss of tooth surface, trauma or pulp exposure. This study aimed to emphasize the influence of computed tomography-guided endodontics on the accuracy and efficacy of endodontic treatments compared to conventional techniques. Articles were selected from PubMed, SCIELO and BVS databases using the descriptors "endodontics OR root canal treatment AND dental calcification AND pulp cavity AND cone beam computed tomography". The study included articles published from 2013 to 2023. After analyzing the inclusion and exclusion criteria, 20 articles were selected. Endodontic treatment of calcified teeth is challenging and can result in failures in root canal instrumentation and disinfection. Also, it leads to complications such as perforation and weakening of the tooth structure due to excessive wear. Thus, minimally invasive endodontics is gaining prominence in contemporary endodontics. New techniques, such as guided endodontics, are emerging and have helped to reduce the risk of root perforation.

Approach for evaluating the effectiveness of ex vivo root canal instrumentation using microtomography

Endodontic treatment of a tooth involves effective elimination of the infectious process localized in the tooth cavity and root canals. The process of root canal treatment is carried out using specialized rotary instruments (files). In this paper, an approach is proposed for evaluating the effectiveness of root canal treatment using the ProTaper Next file system ex vivo using computed X-ray microtomography and VGSTUDIO MAX 3.5 software. This approach involves comparison of three-dimensional tooth models before and after the endodontic instrumentation procedure, segmentation, calculation of the root canal volume using software according to a specially developed protocol, as well as a study of their microgeometry. As an example of using the approach, a study of the features of root canal instrumentation of two- and three-rooted human molars is presented. The developed approach demonstrated high effectiveness in the process of examining human teeth, while the endodontic procedure was effective for both two- and three-rooted molars in terms of removing the internal biological content of the canals, which indicates the reliability of the applied method. The developed approach can be applied to evaluate the effectiveness of liquid dental materials and antibacterial solutions used during endodontic treatment of teeth.

Unveiling the correlation between in vivo endodontic reciprocate instrumentation and crack formation

IntroductionDentinal microcracks have been supposedly associated with unrestorable vertical root fractures and consequently long-term treatment failure. This study aimed to investigate whether in vivo root canal instrumentation in mandibular incisors with vital pulps causes dentinal microcracks using two different irrigating solutions. MethodsFive patients with four vital mandibular incisors indicated for extraction were included. In vivo root canal preparation was performed using Reciproc R40 (tip #40 and taper 0.06). From these, two teeth were randomly assigned for root canal instrumentation irrigated with 5.25 % sodium hypochlorite irrigation (n = 10) or 2 % chlorhexidine gel with saline solution irrigation (n = 10). In sequence, all teeth were carefully extracted, stored in saline solution until microtomography (µCT) scan. Images were reconstructed and assessed for the presence or absence of dentinal microcracks where microcracks originating from the root canal lumen would be considered. All reconstructed samples were analysed dynamically and rendered in videos through the entire extension of the teeth, evaluating the axial cuts considering each third separately from the apex to the enamel-dentinal junction. Teeth were analysed using the DataViewer software at 100 % magnification without filters by three examiners blinded to the condition allocation. ResultsNo complete dentinal microcracks were observed after root canal instrumentation of mandibular incisors with vital pulps using Reciproc R40 regardless the irrigating solutions, 5.25 % sodium hypochlorite or 2 % chlorhexidine gel. ConclusionsIn vivo root canal instrumentation of mandibular incisors with vital pulps and bone/periodontal insertion does not cause dentinal microcracks and the irrigating solutions tested did not influence this occurrence. Microcrack evaluation must be performed in vivo conditions of dental tissue moist and periodontal support to avoid dryness dentinal alterations after extraction provoking false positive results. Clinical relevanceReciprocating instrumentation performed in vivo is safe and do not induce dentinal microcracks in mandibular incisors.

Comparative In Vitro Analysis of Push-Out Bond Strength of Different Root Canal Sealers to Root Dentin

ABSTRACT Aim: The study’s objective is to assess the bond strengths of four different endodontic sealers to root dentin using a push-out test technique. Material and Method: Sixty single-rooted teeth were selected and decoronated. Canal instrumentation was done using rotary files and divided into four groups (n = 15) based on the sealer used. Group 1: zinc oxide eugenol (ZOE)-based, Group 2: epoxy resin-based, Group 3: methacrylate-based, and Group 4: bioceramic. Following obturation with Gutta Percha, each tooth was prepared with root portions that were 2 mm thick at the apical and middle 1/3 so that universal testing equipment could measure the push-out bond strength. Tukey’s post hoc tests and one-way ANOVA were used to examine the data. Result: According to the results, group 4 had the strongest push-out relationship, followed by groups 3, 2, and 1, respectively. It can be concluded that the bioceramic sealers have superior bond strengths. Conclusion: Bioceramic sealers demonstrated the highest bond strengths to root dentin, outperforming methacrylate, epoxy resin, and zinc oxide eugenol sealers in the push-out test.

Static Guided Approach for Obliterated Canal -A Case Report of Maxillary Central Incisor

In recent decades, significant technological advances have deeply influenced our daily lives. Notably, innovations such as 3D printers and 3D cone-beam computed tomography have become valuable tools in clinical dentistry. Diagnosing and treating teeth with pulp canal obliteration presents unique challenge in endodontic procedures. These challenges include the risk of breaking root canal instruments during treatment, preparing overly extended access cavities, and misaligning the access cavity, which could potentially lead to root perforation. Recently, guided endodontics has gained popularity as a method to address these issues. This case report explores the use of guided endodontics in treating a maxillary central incisor with pulp canal obliteration. This approach is advantageous as it reduces the time patients spend undergoing treatment and, more critically, minimizes the risk of inadvertent damage to the tooth structure.

The Middle Mesial Canal: Combined Endodontic and Restorative Treatment Approach - A Case Report

The management of the middle mesial canal (MMC) in mandibular first molars presents considerable challenges during endodontic treatment due to its complex anatomy. Challenges may arise throughout various stages of treatment, including canal location, instrumentation, and obturation. The inability to identify and shape this canal can lead to endodontic failure and post-treatment apical periodontitis. Therefore, understanding this aberrant root canal anatomy and its clinical implications during the various stages of endodontic treatment is essential for successful management, including the selection of the optimal coronal restoration to enhance the efficacy of the obturation’s coronal seal and to ensure the restoration’s maximal longevity. This case report describes the diagnosis and successful endodontic and restorative management of an MMC in a mandibular first molar.

Do the apical limit and diameter of the instrumentation influence the extrusion of sodium hypochlorite solution? A micro-CT study.

This study evaluated the influence of the apical limit and the diameter of the instrumentation on the extrusion of the irrigating solution. Sixty human lower premolars were distributed into 5 groups according to the apical limit and diameter of the root canal instrumentation (n = 12): (G-140) R40 instrument 1mm above the tooth length (TL) (Control); (G-150) R50 instrument 1mm above the TL; (GF25) R25 instrument at the TL; (GF40) R40 instrument at the root canal length and (GF50) R50 instrument at the TL. A space of 33.5 ± 1 mm3 was created for storage of the extruded solution. Omnipaque contrast was added to the NaOCl solution in a 1:2 ratio, totaling 15mL of solution to allow its visualization when extruded in microcomputed tomography. Final irrigation was performed with a syringe and needle and activated with a passive ultrasonic irrigation (PUI). Three activation cycles were performed. Data were tabulated and statistically analyzed (one-way ANOVA) with a significance level set at 5%. It was observed irrigating solution extrusion after final irrigation in all groups. However, there were no statistically significant differences among experimental groups, regardless of the diameter or apical limit of root canal instrumentation (p > 0.05). The different apical limits and diameters of root canal instrumentation did not influence the volume of extruded irrigating solution using passive ultrasonic irrigation.

Antibacterial Efficacy of Rotary and Reciprocating Instrumentation Techniques.

To clinically evaluate the effectiveness of rotary (ProTaper Next [PTN]) and reciprocating (Wave One Gold [WOG]) instrumentation techniques in eliminating bacteria from the root canals of teeth with apical periodontitis during a single-visit root canal treatment. Forty patients were randomly assigned to the WOG or PTN instrumentation techniques groups. A single-visit root canal treatment was performed on all the patients. In both groups, root canals were irrigated with 10 ml of sodium hypochlorite (NaOCl) and the final irrigation protocol was applied. Microbiological samples from the root canal were collected initially (Sample 1), after chemo-mechanical instrumentation (Sample 2), and after the final irrigation protocol (Sample 3). Quantification of bacteria at each stage of root canal treatment was performed using the culture method (colony-forming units [CFUs]), and bacterial species were identified using MALDI-TOF mass spectrometry. There were 55 aerobic and anaerobic bacterial species identified. Chemo-mechanical root canal treatment with both instrumentation techniques and the final irrigation protocol significantly reduced the number of CFUs (p<0.001). There were no statistically significant differences in antibacterial efficacy between WOG and PTN groups (p>0.05). Although both root canal instrumentation techniques were highly effective in removing bacteria from the necrotic canals of teeth with chronic apical periodontitis, no complete eradication of bacteria was found in any sample.

Effect of calcium hydroxide and calcium hydroxide nanoparticles used as intracanal drugs after manual and ultrasonic removal on the bond strength of a new sealer with a pozzolan base (Endoseal mineral trioxide aggregate)

ABSTRACT Aim: The adhesion ability of filling materials to the root canal wall can be affected by the intracanal medicaments. The present study investigated the effect of pretreatment with nano-calcium hydroxide and calcium hydroxide on the bond strength of Endoseal mineral trioxide aggregate (MTA) to root canal dentin. Materials and Methods: Fifty maxillary incisor teeth were randomly divided into two experimental groups (n = 20) and a control group (n = 10) after decoronation near the cementoenamel junction and root canal instrumentation according to the type of intracanal medicament (calcium hydroxide and nano-calcium hydroxide). Each experimental group was divided into two subgroups based on manual and ultrasonic drug removal methods. After removing intracanal medicaments and irrigating them, all the groups were obturated with gutta-percha and Endoseal MTA sealer. Then, the samples were sectioned into cross-sections with a thickness of 2 mm using a diamond disc, and the push-out bond strength test was performed on them. Results: The results showed no significant difference in the mean Endoseal MTA bond strength in terms of the type of intracanal medicament and the method used to remove it from the canal (P &gt; 0.05). Conclusion: Using the ultrasonic method compared to the manual method in removing intracanal medicament resulted in no significant difference in the strength of the Endoseal MTA bond. Furthermore, the effect of nanoparticle calcium hydroxide on Endoseal MTA bond strength was not different compared to the conventional type of this medication.

Influence of occlusal surface reduction on post endodontic pain following instrumentation and obturation: A randomized double blinded clinical study.

The purpose of this randomized clinical study was to investigate the influence of occlusal surface reduction on postendodontic pain. Sixty patients were included with a diagnosis of acute irreversible pulpitis and acute apical periodontitis and divided randomly into two groups. In the intervention group, occlusal surfaces were reduced and left intact in the control group. Postoperative pain was evaluated at the 6th, 12th, 24th, and 48th h after the root canal instrumentation and 6th and 12th h following obturation using visual analog scale. Data were evaluated using the Chi-square test, t-test, Friedman test, Mann-Whitney U-test, and Wilcoxon rank test. Postoperative pain levels in both groups were reduced significantly over the time period evaluated, however, between the two groups, there was no difference evident. Occlusal surface reduction did not influence the pain following root canal instrumentation and obturation.

Major root endodontic treatments: a systematic review

Introduction: In the root canal treatment scenario, irrigation is one of the most important aspects of the biomechanical preparation of the root canal. A condition for successful endodontic retreatment is adequate cleaning of the root canals, therefore, special attention should be paid to the technique used to remove the filling material, the most commonly used being cement, pastes, and gutta-percha cones. Objective: This study aimed to present the main root endodontic treatments to analyze and compare the techniques for removing pulp tissue debris resulting from root preparation and microorganisms from the canals of the root canal system, seeking complete cleaning and asepsis. Methods: The PRISMA Platform systematic review rules were followed. The search was conducted from April to July 2024 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: 129 articles were found, 39 were evaluated and 21 were included in this systematic review. Considering the Cochrane tool for risk of bias, the global assessment resulted in 25 studies with a high risk of bias and 27 studies that did not meet GRADE. Most studies showed homogeneity in their results, with X2 =91.5% &gt;50%. It was concluded that the system of root canal instrumentation with rotary files maintains the quality of root preparation and, at the same time, reduces the number of files required to obtain a canal, which would consequently reduce the operative time and also considerably reduce the risk of torsion fracture within the root canal than with files. Irrigation plays a fundamental role in the success of endodontic treatment. Although hypochlorite is the most important irrigant solution, no irrigant can perform all the tasks required by irrigation. A detailed understanding of the mode of action of various solutions is important for optimal irrigation. Within the limitations of this study, the use of the self-adjusting file with the combination of EDTA and NaOCl improved Ca(OH)2 removal. Passive ultrasonic irrigation and the self-adjusting file were more effective in removing Ca(OH)2 from the lateral sulci in the apical parts of the root canal than the EndoVac and conventional syringe irrigation systems.

A qualitative and quantitative evaluation of smear layer removal efficacy of three different chelating agents using scanning electron microscopy and inductively coupled plasma mass spectrometry

ABSTRACT Aim: The main goal of the present experimental research was to analyze the smear layer removal efficacy of chelating agents and correlate with the amount of calcium released from the radicular dentin with the canal space. Materials and Methods: Forty single-rooted teeth were exposed to standardized root canal instrumentation technique with copious amount of irrigation with 2.5% sodium hypochlorite solution between each instrumentation, following which the specimens were randomly allocated into four groups: Group I: 17% ethylenediaminetetraacetic acid (EDTA), Group II 0.2% Chitosan, Group III Qmix™, and Group IV Control group with no final irrigation. After the irrigation protocol, the specimens were subjected to the scanning electron microscopy (SEM) evaluation to determine the smear layer removal efficacy and induced plasma mass spectrophotometric analysis was done to quantify the amount of calcium ions content in the irrigating solution. The data were statistically analyzed using Kruskal–Wallis and Dunnett’s tests for smear layer removal analysis. Quantitative data were interpreted by the analysis of variance and Tukey’s-Karmer test for the spectroscopic data analysis. Results: The result of the SEM analysis showed that there was no significant difference among the smear layer removal efficacy between the experimental groups with P &gt; 0.05. The quantitative spectrophotometric data showed that the highest calcium ions release was from the 17% EDTA group followed by 0.2% chitosan and lesser from the Qmix™ group. Conclusion: Within the limitation of this in vitro experimental research, all the three experimental groups showed a better smear layer removal efficacy. EDTA showed the greater amount of mineral release compared to Qmix™ and chitosan group.

Effect of repetitive up-and-down movements on torque/force generation, surface defects and shaping ability of nickel-titanium rotary instruments: an ex vivo study

BackgroundThe screw-in effect is a tendency of a nickel-titanium (NiTi) rotary endodontic file to be pulled into the canal, which can result in a sudden increase in stress leading to instrument fracture, and over-instrumentation beyond the apex. To reduce screw-in force, repeated up-and-down movements are recommended to distribute flexural stress during instrumentation, especially in curved and constricted canals. However, there is no consensus on the optimal number of repetitions. Therefore, this study aimed to examine how repeated up-and-down movements at the working length affect torque/force generation, surface defects, and canal shaping ability of JIZAI and TruNatomy instruments.MethodsAn original automated root canal instrumentation device was used to prepare canals and to record torque/force changes. The mesial roots of human mandibular molars with approximately 30˚ of canal curvature were selected through geometric matching using micro-computed tomography. The samples were divided into three groups according to the number of up-and-down movements at the working length (1, 3, and 6 times; n = 24 each) and subdivided according to the instruments: JIZAI (#13/0.04 taper, #25/0.04 taper, and #35/0.04 taper) or TruNatomy (#17/0.02 taper, #26/0.04 taper, and #36/0.03 tape) (n = 12 each). The design, surface defects, phase transformation temperatures, nickel-titanium ratios, torque, force, shaping ability, and surface deformation were evaluated. Data were analyzed with the Kruskal-Wallis and Dunn’s tests (α = 0.05).ResultsThe instruments had different designs and phase transformation temperatures. The 3 and 6 up-and-down movements resulted in a smaller upward force compared to 1 movement (p < 0.05). TruNatomy generated significantly less maximum torque, force, and surface wear than JIZAI (p < 0.05). However, TruNatomy exhibited a larger canal deviation (p < 0.05). No statistical differences in shaping ability were detected between different up-and-down movements.ConclusionsUnder laboratory conditions with JIZAI and TruNatomy, a single up-and-down movement at the working length increased the screw-in force of subsequent instruments in severely curved canals in the single-length instrumentation technique. A single up-and-down movement generated more surface defects on the file when using JIZAI. TruNatomy resulted in less stress generation during instrumentation, while JIZAI better maintained the curvature of root canals.

Critical Factors Affecting Outcomes of Endodontic Microsurgery: A Retrospective Japanese Study.

The critically important preoperative and intraoperative factors that affect the success of endodontic microsurgery (EMS) in Japanese patients are not defined. We conducted a retrospective study that analyzed treatment outcomes for 46 teeth in 46 Japanese patients. Treatment was provided between March 2013 and March 2015. All patients were evaluated after one year, the shortest time period over which treatment outcomes after apicoectomy could be evaluated and in which there were complete records for the recruited patient population. Healing was assessed on the basis of clinical symptoms and radiographs. With the use of a binary logistic regression model to quantify success, we estimated the effects of patient age, sex, dental arch, lesion size, lesion type, preoperative root canal treatment, the presence or absence of a post core, and the presence or absence of an isthmus on the surgically prepared dentine surface. The overall success for EMS was 93.5% after one year; failures comprised 6.5%. Successful outcomes were higher (p = 0.04) for maxillary teeth than for mandibular teeth. Success was higher (p = 0.019) for patients who received root canal instrumentation prior to EMS. Age, sex, lesion size, lesion type, the presence or absence of a post core, and the presence or absence of a root canal isthmus had no effect (p > 0.2) on success. We conclude that the percentage of successful outcomes after EMS treatment for Japanese patients presenting with periapical periodontitis is very high after one year and that success is influenced strongly by the dental arch and preoperative root canal instrumentation.

The Impact of Minimum Invasive Access Cavity Design on the Quality of Instrumentation of Root Canals of Maxillary Molars Using Cone-Beam Computed Tomography: An in Vitro Study.

Aim Minimally invasive dentistry has been facilitated by advances in instruments and restorative materials. This study aims to compare the change in the shaping ability of the RECIPROC blue rotary system in both traditional and conservative access cavities, using cone beam computed tomography (CBCT). Material and methods Sixty root canals of 20 artificial maxillary molars were assigned into two groups (n=30 root canals) according to the access cavity design used: Group I: traditional access cavity (TAC) and Group II: conservative access cavity (CAC). CBCT scans of samples were made before and after root canal preparation using the RECIPROC blue rotary system. The shaping parameters are evaluated in root canal transportation and the centering ability. Three CBCT sections per tooth were analyzed at 3, 6, and 9 mm from the apex to assess the canal transportation and centering ability at three levels, apical, middle, and coronal thirds. Data were analyzed using the GraphPad Prism (GraphPad Software, San Diego, CA). Results The results of this study showed a significant difference in transportation within the coronal and middle thirds. However, in apical thirds, there were no significant differences. Both groups observed a significant difference in the centering ability in the coronal third. Conclusion Within the limitations of this study, CAC can be recommended with caution as an alternative access to TAC.

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.

Comparative effects of the conventional, ultrasonic, and laser-activated irrigation on penetration depth of three photosensitizers in the root canal system

ObjectivesThis study compared the effects of conventional, ultrasonic, and laser-activated irrigation (LAI) on penetration depth of three photosensitizers (PSs) in the root canal system. Materials and MethodsIn this in vitro, experimental study, 120 extracted anterior teeth were decoronated such that the remaining root length was standardized at 12 mm. After root canal instrumentation with the ProTaper rotary system and irrigation with 5.25% NaOCl, the roots were assigned to 12 groups for the application of toluidine blue (TB), curcumin, and phycocyanin PSs combined with the LAI using erbium laser with 0.4 mm and 0.6 mm tips, ultrasonic activation, and conventional irrigation. The specimens were sectioned apicocoronally, and the dye penetration depth was quantified in the coronal, middle, and apical thirds under a stereomicroscope at x20 magnification. Data were analyzed by the Kruskal-Wallis and Dunn test (alpha=0.05). ResultsThe effects of irrigation technique, PS type, and their interaction on dye penetration depth were significant at the apical, middle, and coronal thirds (P < 0.0001). TB + LAI with 0.4- and 0.6-mm laser tips showed the highest penetration depth while phycocyanin + LAI or conventional irrigation showed the lowest penetration depth at all areas. Dye penetration depth was the highest in the coronal, and the lowest in the apical third. ConclusionThe LAI technique with erbium laser (0.4- and 0.6-mm tips) enhanced the penetration depth of TB. The tested irrigation techniques had no significant efficacy for enhancement of the penetration depth of curcumin and phycocyanin.