Search Results (58)

Objectives: Endodontic instruments require thorough decontamination and sterilization before use and reuse to ensure the safety and success of treatments. However, standardized protocols are lacking. This study aimed to quantitatively assess the effectiveness of different cleaning protocols in removing debris from NiTi rotary file surfaces. Methods: Forty-eight new Mtwo NiTi rotary instruments (sizes 10/.04, 15/.05, 20/.06, and 25/.06) were randomly assigned to four groups (n = 12). A set of new sterile instruments (Group I) served as the negative control. After usage for primary endodontic treatment, instruments underwent different cleaning protocols: steam sterilization without cleaning (Group II); ultrasonic cleaning + steam sterilization (Group III); and manual cleaning with a scouring sponge + ultrasonic cleaning + steam sterilization (Group IV). Back-scattered scanning electron microscopy (SEM) micrographs of the apical, middle, and coronal sections were processed using Fiji software (version 2.14.0) to quantify debris as a percentage of the total selected area. Results: No significant differences were found among the three sections within each group, although higher debris amounts were observed from coronal to apical in Groups I and II. Group I had the least debris, while Group II showed the most, with statistically significant differences compared to other groups (p < 0.05). There was no significant difference between Groups III and IV, though Group IV showed notably less debris. Conclusions: The combination of mechanical, chemical, and ultrasonic cleaning proved most effective at removing debris from endodontic instruments. Current cleaning methods, however, remain insufficient for complete debris removal, highlighting the need for further research to standardize and improve cleaning and sterilization protocols or preferably use single-use/single-patient instruments. Full article

The aim of this study was to evaluate the effects of mechanized final irrigation protocols (XPE, XP-Endo Finisher; XPC, XP-Clean; and ECL, Easy Clean) compared to PUI (passive ultrasonic irrigation) on the debris incidence and open dentinal tubules, and their effects on the adhesion interface after 48 h and 6 months. One hundred twenty maxillary central incisors were submitted to chemical–mechanical preparation using a rotary instrument and 2.5% sodium hypochlorite. Specimens were distributed in 4 groups (n = 30) in accordance with the mechanized final irrigation protocol: XPE, XPC, ECL, or PUI. Forty specimens (n = 10/group) were submitted to SEM analysis to evaluate the residue incidence and dentin open tubules. The other specimens were obturated using Bio-C Sealer and submitted to push-out bond strength and adhesive failure mode evaluations in the cervical, middle, and apical thirds after 48 h or 6 months (n = 10/group). Only in the apical third, ECL presented the highest residue incidence and fewer open dentinal tubules when compared to the XPE, XPC, and PUI groups (p < 0.05). In the cervical and middle root thirds, no significant differences were observed regardless of the group evaluated (p > 0.05). After 48 h, ECL resulted in the lowest bond strength only in the apical third (p < 0.05), while the XPE, XPC, and PUI groups remained similar in the cervical and middle thirds (p > 0.05). At 6 months, all groups showed lower bond strength values regardless of the root third evaluated, but ECL showed the lowest bond strength in the apical and middle root thirds when compared to the other groups (p < 0.05). The ECL protocol did not provide adequate residue removal on the apical radicular third and negatively affected the longevity of endodontic obturation using a calcium silicate-based sealer. Full article

Background/Objectives: 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. Methods: 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. Results: 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. Conclusions: 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. Full article

Objectives: The objective of the present study was to evaluate the cyclic fatigue strength of clockwise cutting rotary endodontic instruments when subjected to two different kinematics: continuous clockwise rotation and clockwise reciprocation movement under optimum torque reverse (OTR) motion. Methods: New ProTaper Next X1 (n = 20) and X2 (n = 20) instruments were randomly divided into two subgroups (n = 10) based on kinematics (continuous rotation or OTR). The specimens were tested using a custom-made device with a non-tapered stainless-steel artificial canal measuring 19 mm in length, featuring a 6 mm radius and an 86-degree curvature. All instruments were tested with a lubricant at room temperature until a fracture occurred. The time to fracture and the length of the separated fragment were recorded. Subsequently, the fractured instruments were inspected under a scanning electron microscope for signs of cyclic fatigue failure, plastic deformation, and/or crack propagation. The subgroup comparisons for time to fracture and instrument length were performed using the independent samples t-test, with the level of statistical significance set at 0.05. Results: When using OTR movement, the ProTaper Next X1 increased the time to fracture from 52.9 to 125.8 s (p < 0.001), while the ProTaper Next X2 increased from 45.4 to 66.0 s (p < 0.001). No subgroup exhibited plastic deformations, but both showed dimpling marks indicative of cyclic fatigue as the primary mode of failure. Additionally, OTR movement resulted in more metal alloy microcracks. Conclusions: The use of OTR motion extended the lifespan of the tested instruments and resulted in a higher number of metal microcracks. This suggests that OTR motion helped to distribute the mechanical stress more evenly across the instrument, thereby relieving localized tension. As a result, it delayed the formation of a single catastrophic crack, enhancing the overall performance of the instruments during the experimental procedures. Full article

Background: Rotary Ni-Ti files are susceptible to sudden intra-canal separation due to cyclic fatigue stress, particularly in curved canals. To increase resistance to cyclic fatigue, new heat-treated files have been introduced. This study aimed to compare the performance of four heat-treated Ni-Ti files in two simulated curved root canals by evaluating the effect of the alloy, rotation speed, and diameter of the files on their resistance to cyclic fatigue. Methods: The Ni-Ti files included in the study were the ProTaper Gold^® (Dentsply Sirona) F2, ProTaper Ultimate^® (Dentsply Sirona) F2, FQ^® (Komet) 25.06, and Blueshaper^® (Zarc4Endo) Z4 25.06. Two groups of 30 files were selected for each system and were tested in two simulated canals milled in a specific metal template. One group was tested in a 60° curved canal and the other in a 90° curved canal. Results: In the 60° simulated canal, there were no instrument fractures within the 15 min time limit. In the 90° simulated canal, the Blueshaper Z4 demonstrated a lower resistance to cyclic fatigue, while FQ 25.06 showed statistically higher fatigue resistance based on both the Kruskal–Wallis and Games–Howell tests (p < 0.05). Conclusions: No differences were found between files when tested in a 60° curved canal for up to 15 min. However, in a 90° canal, the FQ^® files showed significantly higher resistance to cyclic fatigue, especially compared to the Blueshaper^® Z4. The ProTaper Ultimate and ProTaper Gold produced intermediate results, with the ProTaper Ultimate F2 slightly outperforming the ProTaper Gold F2. Full article

Root canal therapy (RCT) is usually performed in Romania by general dentists (GDPs) because they are more readily available and more reasonably priced than endodontists. Concerns have been raised about the quality of RCTs performed by GDPs, possibly due to insufficient equipment or knowledge; therefore, this study aims to investigate current endodontic practices in Romania. Materials and Methods: A cross-sectional study was conducted via a questionnaire distributed to 400 randomly selected Romanian dentists, with 285 fully validated completed responses (71.25% response rate). Respondents were grouped by speciality, and statistical analysis, including cross-tabulation and the χ² (chi-square) test, was used, with a significance level set at p ≤ 0.05 for all tests. Results: Significant differences were found in the use of magnification, rubber dam, sodium hypochlorite concentration, and bioceramics (p < 0.001). No significant differences were observed in preferences for measuring working length (p = 0.166) or rotary instrument motion (p = 0.289). Approximately 6% of the respondents used laser technology with no significant difference across specialities (p = 0.571). Additionally, 77.9% preferred using sodium hypochlorite, with no significant difference between groups (p = 0.006) regarding concentration. Conclusions: Most participants, including GDPs, use modern equipment and techniques during RCT, indicating their awareness and competence in current endodontic practices. Full article

The introduction of nickel–titanium rotary instruments revolutionized shaping procedures as they were able to produce a well-tapered preparation while reducing operator fatigue. The major drawback of rotary instruments was the high risk of fracture due to bending and torsional stress. Thus, the creation of a glide path has been advocated and recommended by most rotary instrument manufacturers. The aim of the present review is to summarize existing knowledge on glide path preparation and identify areas where further research is needed. The primary goal is to provide a comprehensive overview of the techniques and instruments used in glide path preparation, highlighting their advantages and limitations. The secondary goal is to explore the effect of glide path creation on the overall success of endodontic treatment, particularly in terms of reducing procedural errors and improving treatment outcomes. An online search on PubMed, ScienceDirect, UCLA, and Scopus databases was conducted, and 116 articles were identified. Eligible articles were divided into nine categories based on what they researched and compared. The categories included centering ability and/or root canal transportation, cyclic fatigue resistance, glide path and shaping time, tortional stress resistance, apical extrusion of debris and/or bacteria, defects in dentine walls, file separation, postoperative pain assessment, and scouting ability and performance. Establishing a glide path reduces root canal transportation, especially with rotary methods. Reciprocating and heat-treated files offer higher fatigue resistance and shorter preparation time. Instruments with shorter pitch lengths have greater torsional strength. Preparation and coronal preflaring reduce apical debris and bacteria. Glide paths do not affect dentine microcracks, file separation, or defects but reduce immediate postoperative pain and improve cutting ability. Randomized trials are needed to assess their impact on treatment outcomes. Full article

Introduction: Modern endodontics aims to decrease the bacterial load from the complex endodontic space. Over the years, improvements in the operative phases have led to a considerable increase in the success rate of endodontic treatments. The shaping phase has seen the development of new techniques supported by technological innovations that have led to higher treatment predictability. Endodontic instruments have experienced a series of changes that have led to modifications in their design, surface treatments, and heat treatments. The clinical use of rotating nickel–titanium instruments has become widespread and consolidated, a success due primarily to the alloy’s mechanical characteristics, which are superior to steel ones, but also to innovations in instrument design. The advent of the Ni-Ti alloy has kept the concepts and requirements of shaping the same but has modified its implementation in endodontics. Aim: The following review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) protocol. The research question focused on Ni-Ti endodontic instruments whose cyclic fatigue was evaluated by analyzing cyclic fatigue strength and the incidence of fracture. Results: At the end of the research, 10 systematic reviews and 1 randomized controlled trial were included in this comprehensive review. The most frequently analysed alloys were M-wire, conventional Ni-Ti, and CM-wire. In seven articles, instruments made of M-wire alloy were used; in eight articles, instruments made of conventional Ni-Ti; and in seven articles, instruments made of CM-wire alloy. Conclusions: The technological evolution of Ni-Ti alloys has led to the development of increasingly high-performance endodontic files that are resistant to cyclic fatigue during clinical practice and have greater resistance to sterilisation practices, making treatment easier and more predictable over time. In particular, heat-treated nickel-titanium root canal instruments present greater resistance to cyclic fatigue than untreated ones and those used with reciprocating kinematics concerning continuous rotation. Full article

The resistance of nickel–titanium endodontic instruments against cyclic fatigue failure remains a significant concern in clinical settings. This study aimed to assess the cyclic fatigue strength of five nickel–titanium rotary systems, while correlating the results with the instruments’ geometric and metallurgical characteristics. A total of 250 new instruments (sizes S1/A1, S2/A2, F1/B1, F2/B2, F3/B3) from ProTaper Gold, ProTaper Universal, Premium Taper Gold, Go-Taper Flex, and U-Files systems underwent mechanical testing. Prior to experimental procedures, all instruments were meticulously inspected to identify irregularities that could affect the investigation. Using a stereomicroscope, design characteristics such as the number of spirals, length, spirals per millimeter, and average helical angle of the active blade were determined. The surface finishing characteristics of the instruments were examined using a scanning electron microscope. Differential scanning calorimetry was employed to establish the instruments’ phase transformation temperatures, while energy-dispersive X-ray spectroscopy was utilized to analyze the elemental composition of the alloy. The instruments were subjected to cyclic fatigue testing within a stainless steel non-tapered artificial canal featuring a 6 mm radius and 86 degrees of curvature. Appropriate statistical tests were applied to compare groups, considering a significance level of 0.05. The assessed design characteristics varied depending on the instrument type. The least irregular surface finishing was observed in U-Files and Premium Taper Gold files, while the most irregular surface was noted in Go-Taper Flex. All instruments exhibited near-equiatomic proportions of nickel and titanium elements, whereas ProTaper Universal and U-Files instruments demonstrated lower phase transformation temperatures compared to their counterparts. Larger-sized instruments, as well as ProTaper Universal and U-Files, tended to display lower cyclic fatigue strength results. Overall, the design, metallurgical, and cyclic fatigue outcomes varied among instruments and systems. Understanding these outcomes may assist clinicians in making more informed decisions regarding instrument selection. Full article

(1) Background: The failure of nickel–titanium (NiTi) rotary files is a complication related to endodontic instruments. The aim of this study was to compare the resistance to cyclic fatigue between rotary and reciprocating file systems. (2) Methods: Specific PICO: Population (P): artificial root canals; Interventions (I): instrumentation with NiTi rotary and reciprocating files; Comparison (C): rotary versus reciprocating files; Outcome (O): cyclic fatigue resistance. Studies were identified through bibliographic research using electronic databases (Medline, Embase, Scopus, SciELO, and WOS). The studies were combined using a random effects model by the inverse variance method. The effect size was the mean of the time to fracture (TTF) and number of cycles to fracture (NCF). Heterogeneity was assessed using the p value of the Q test for heterogeneity and the I2. (3) Results: TTF for rotary files was determined in 474.5 s and 839.1 for reciprocating without statistically significant differences. NCF for rotary systems was determined in 1444.2 and for reciprocating file systems in 4155.9 with statistically significant differences (p = 0.035), making reciprocating files more resistant. (4) Conclusions: Reciprocating files have better resistance to cyclic fatigue than rotary files. When tested in double curvature canals, reciprocating files also showed higher resistance. Full article

(1) The possibility of knowing information about the anatomy in advance, in particular the arrangement of the endodontic system, is crucial for successful treatment and for avoiding complications during endodontic therapy; the aim was to find a correlation between a minimally invasive and less stressful endodontic access on Ni-Ti rotary instruments, but which allows correct vision and identification of anatomical reference points, simplifying the typologies based on the shape of the pulp chamber in coronal three-dimensional exam views. (2) Based on the inclusion criteria, 104 maxillary molars (52 maxillary first molars and 52 maxillary second molars) were included in the study after 26 Cone Beam Computed Tomography (CBCT) acquisitions (from 15 males and 11 females). And linear measurements were taken with the CBCT-dedicated software for subsequent analysis. (3) The results of the present study show data similar to those already published about this topic. Pawar and Singh’s simplified classification actually seems to offer a schematic way of classification that includes almost all of the cases that have been analyzed. (4) The use of a diagnostic examination with a wide Field of View (FOV) and low radiation dose represents an exam capable of obtaining a lot of clinical information for endodontic treatment. Nevertheless, the endodontic anatomy of the upper second molar represents a major challenge for the clinician due to its complexity both in canal shape and in ramification. Full article

(1) Background: The aim of this study was to investigate the cyclic fatigue behavior of the newly introduced endodontic instrument systems Tia Tornado Blue and Tia Tornado Gold. (2) Methods: The tested rotary instruments were divided according to their type into four groups as follows: Tia Tornado Blue (TTB), Tia Tornado Gold (TTG), Protaper Gold (PTG), and Vortex Blue (VB). The cyclic fatigue resistance of fifteen instruments of each group, totaling 60, was tested. Each instrument was rotated under continuous motion inside an artificial canal at simulated body temperature at the speed recommended by the manufacturer until fracture. The time to fracture was recorded, and the number of cycles to fracture (NCF) was calculated for each instrument. Additionally, the fractured segment length was calculated, and scanning electron microscopic (SEM) images were captured of the fractured surfaces. (3) Results: Statistical analysis revealed that the VB significantly had the highest NCF followed by the PTG, TTG, and TTB (p < 0.05). The lengths of the fractured segments were found to be similar among the tested instrument, which ranged from 4.42 to 4.86 mm (p > 0.05). SEM images exhibited the typical features of cyclic fatigue. (4) Conclusions: The newly introduced instruments, TTG and TTB, exhibited a significantly lower resistance to cyclic fatigue compared to the PTG and VB rotary instruments. Full article

The elimination of necrotic and inflamed pulp tissue, dentin debris, and microorganisms is essential for the success of endodontic treatment. However, the root canal’s complexity has led to incomplete cleaning and disinfection. This study aims to compare the efficacy of the penetrability of three different irrigation activating techniques to the apical third of the root canal. Sixty sound single-rooted human mandibular premolars are prepared with rotary instrumentation under continuous sodium hypochlorite irrigation. Three irrigation activation techniques are utilized: group 1 (n = 20), conventional needle irrigation (CN); group 2 (n = 20), side-vented endodontic needle irrigation (EN); and group 3 (n = 20), manual activation irrigation with gutta-percha cone (MA). The penetrability is assessed with the aid of a radiopaque irrigation solution using digital radiography in conjunction with cone-beam computed tomographic (CBCT) measurements. Data are analyzed using a statistical package for social sciences (SPSS), using multiple comparisons to compare the baseline and test values. One-way analysis of variance with post hoc analysis (Tukey honestly significant difference) is performed to detect the statistically significant differences between groups. Manual activation (MA) shows effective delivery of the irrigant into full WL, followed by endodontic needle (EN) and conventional (CN) methods of activation (p < 0.001). The results of the present study show that maximum penetrability of the irrigant is observed with manual activation (MA) using a gutta cone in comparison with the conventional needle (CN). Full article

One of the most used rotary files in endodontics is NiTi files due to their superelastic properties. This property means that this instrument has extraordinary flexion that can adapt to large angles inside the tooth canals. However, these files lose their superelasticity and fracture during use. The aim of this work is to determine the cause of fracture of the endodontic rotary files. For this purpose, 30 NiTi F6 SkyTaper^® files (Komet, Germany) were used. Their chemical composition was determined by X-ray microanalysis, and their microstructure was determined by optical microscopy. Successive drillings were carried out with artificial tooth molds at 30, 45, and 70°. These tests were carried out at a temperature of 37 °C with a constant load controlled by a high sensitivity dynamometer of 5.5 N, and every five cycles were lubricated with an aqueous solution of sodium hypochlorite. The cycles to fracture were determined, and the surfaces were observed by scanning electron microscopy. Transformation (austenite to martensite) and retransformation (martensite to austenite) temperatures and enthalpies were determined by Differential Scanning Calorimeter at different endodontic cycles. The results showed an original austenitic phase with a M_s temperature of 15 °C and A_f of 7 °C. Both temperatures increase with endodontic cycling, indicating that martensite forms at higher temperatures, and the temperature must be increased with cycling to retransform it to austenite. This fact indicates the stabilization of martensite with cycling, which is confirmed by the decrease in both transformation and retransformation enthalpies. The martensite is stabilized in the structure due to defects and does not retransform. This stabilized martensite has no superelasticity and, therefore, fractures prematurely. It has been possible to observe the stabilized martensite by studying the fractography, observing that the mechanism is by fatigue. The results showed that the files fracture earlier the greater the angle applied (for the tests at 70° at 280 s, at 45° at 385 s, and at 30° at 1200 s). As the angle increases, there is an increase in mechanical stress, and, therefore, the martensite stabilizes at lower cycles. To destabilize the martensite, a heat treatment can be carried out at 500 °C for 20 min, and the files recovers all its superelasticity. Full article

The success of endodontic treatment is dependent on the removal of bacteria. A modern strategy to reduce bacterial load is laser irradiation. During this procedure, there is a local increase in temperature with possible side effects. The aim of this study was to determine the thermal behavior of a maxillary first molar when performing the conventional irradiation technique using a diode laser. For this study, a 3D virtual model of a maxillary first molar was created. The preparation of the access cavity, the rotary instrumentation of the palatal root canal and the laser irradiation protocol were simulated. The model was exported in a finite element analysis program where the temperature and heat flux were studied. Temperature and heat flux maps were obtained, and the temperature increase on the internal wall of the root canal was analyzed. The maximum temperature value exceeded 400 °C and was maintained for less than 0.5 s. The obtained temperature maps support the bactericidal effect of diode laser and the limitation of damage to surrounding tissues. On internal root walls, the temperature reached several hundred degrees Celsius, but for very short durations. Conventional laser irradiation is an adjuvant method of decontamination of the endodontic system. Full article