Evaluation Algorithm of Root Canal Shape Based on Steklov Spectrum Analysis.

In recent years, we have seen more and more interest in the field of medical images and shape comparison motivated by the latest advances in microcomputed tomography (µCT) acquisition, modelling, and visualization technologies. Usually, biologists need to evaluate the effect of different root canal preparation systems. Current root canal preparation evaluation methods are based on the volume difference, area difference, and transportation of two root canals before and after treatment. The purpose of root canal preparation is to minimize the volume difference and ensure the complete removal of the smear layer. Previous methods can reflect some general geometric differences, but they are not enough to evaluate the quality of root canal shape. To solve this problem, we proposed a novel root canal evaluation method based on spectrum and eigenfunctions of Steklov operators, which can be served as a better alternative to current methods in root canal preparation evaluation. Firstly, the ideal root canal model was simulated according to the root canal model before and after preparation. Secondly, the Steklov spectrum of the two models was calculated. Thirdly, based on the spectrum and the histogram of the Gaussian curvature on the surface, the weight of each eigenvalue was computed. Therefore, the Steklov spectrum distance (SSD), which measures shape difference between the root canals, was defined. Finally, the calculation method that quantifies the root canal preparation effect of root canals was obtained. Through experiments, our method manifested high robustness and accuracy compared with existing state-of-the-art approaches. It also demonstrates the significance of our algorithm's advantages on a variety of challenging root canals through result comparison with counterpart methods.

Remaining dentine thickness of root canals prepared with K-3 and ProTaper rotary systems.

OBJECTIVE: To compare the remaining dentine thickness of root canals prepared with K-3 and ProTaper files.. METHODS: This in-vitro experimental study was conducted from 1st April-30th September 2015 at the dental clinics of Aga Khan University Hospital, Karachi, and comprised human teeth. Extracted human premolars and molars were included in the study using non-probability consecutive sampling. Canals were randomly allocated into two groups i.e. K-3 and ProTaper. Changes in inner and outer walls of canals were measured using Vixwin software at 1mm, 4mm, 7mm and 10mm from the apex. SPSS 20 was used for data analysis. RESULTS: Of the 214 canals, 107(50%) were assigned to each group. No statistically significant difference was found in the remaining dentine thickness at 1mm, 4mm, 7mm and 10mm from the apex of the teeth prepared with in K-3 versus ProTapers system (p>0.05). CONCLUSIONS: The remaining dentine thickness of the root canals prepared with K-3 files was similar to that of canals prepared with ProTaper files.

Glide Path Enlargement of Mandibular Molar Canals by Using K-files, the ProGlider File, and G-Files: A Comparative Study of the Preparation Times.

INTRODUCTION: The preparation of a glide path before the introduction of rotary nickel-titanium instruments is a standard adjunct to ensure increased safety during root canal preparation. The aim of this study was to compare the mean preparation time of manual instrumentation with K-files, G-Files, and the ProGlider instrument to prepare a glide path in curved root canals. METHODS: The mesial canals of 90 mandibular molars (with curvature angles between 25° and 35°) were selected. The specimens were randomly divided into 3 groups with 30 canals each, and canal preparations were performed by an endodontist who used #10-15-20 stainless steel manual K-files (group KF), #10 stainless steel manual K-file followed by #12-17 G-File instruments (group GF), and #10 stainless steel manual K-file followed by #16 ProGlider instrument (group PG). The total time it took to prepare the glide paths was recorded with an electronic stopwatch. New instruments were used for each canal. RESULTS: Glide path enlargement with the PG group (27.9 ± 8.6 seconds) and GF group (41.9 ± 20.1 seconds) was shown to be statistically significantly faster than stainless steel KF group (74.9 ± 24.1 seconds) by using analysis of variance (P < .05). There was no statistically significant difference observed between the mean preparation times of the PG and GF groups (P < .05). CONCLUSIONS: Glide path preparation times with the rotary instrument groups were significantly faster than with stainless steel manual K-files.

Um novo conceito na instrumentação de canais radiculares ­ sistema HyFlex® cm™ / A new concept in root canal instrumentation ­ HyFlex® cm™ system

Para o sucesso do tratamento endodôntico é essencial a perfeita limpeza, conformação e desinfecção do canal radicular, obtendo-se uma forma cônica, respeitando a sua forma original, promovendo assim, condições necessárias para que o sistema de canais radiculares possa ser hermeticamente obturado. O preparo biomecânico sofreu grandes transformações nos últimos anos, sendo a instrumentação manual gradualmente substituída pelos sistemas mecanizados. Uma das principais inovações em Endodontia foi a introdução da liga de níquel-titânio (NiTi) para fabricação de instrumentos endodônticos, permitindo que os mesmos trabalhassem dentro dos canais radiculares. Apesar das apreciáveis propriedades mecânicas da liga de NiTi convencional, a separação dos instrumentos continua sendo uma preocupação. Entre os novos sistemas mecanizados de NiTi que visam amenizar esta problemática, vale destacar os que apresentam uma liga melhorada por processos térmicos. Dentre deles o sistema HyFlex® CM™ (ColténeEndo/Whaledent, Inc, Cuyahoga Falls, OH, EUA) torna-se uma excelente alternativa por sua alta resistência à fadiga cíclica e possibilidades de serem pré-curvados. Por tanto, o objetivo deste trabalho é apresentar o sistema HyFlex® CM™ através de um caso clínico (AU).

For the success of endodontic treatment, perfect cleaning, shaping and disinfection of the root canal are essential as well as getting a conical shape, similar to its original shape, enabling the conditions for hermetic sealing of the root canal system. The step that has undergone major changes in recent years was the biomechanical preparation with gradual mechanized systems to "substitute" the manual preparation. One of the main innovations in Endodontics was the introduction of nickel-titanium (NiTi) for manufacturing endodontic instruments. Despite the good mechanical properties of conventional NiTi alloy, fracture of the instruments remains a concern. Among the new mechanized systems of NiTi, treated by thermal processes which improved NiTi alloy, the HyFlex® CM™ system (ColténeEndo / Whaledent, Inc, Cuyahoga Falls, OH, USA) becomes an excellent alternative to endodontic therapy. Therefore, the objective of this study was to present a clinical case using mechanized instrumentation with HyFlex® CM™ system (AU).

Development and Evaluation of an Endodontic Simulation Model for Dental Students.

The aims of this study were to develop an endodontic simulation model able to implement the electronic method of working length determination (electronic apex locators, EALs) in a dental school, to evaluate the practicality of this tool for dental students, and to compare the accuracy of working length measurements achieved by the EAL and the radiographic method. A new simulation model was constructed by embedding extracted human teeth in a self-cured resin, along with a conductive medium. After radiographic and electronic working length determinations, root canal instrumentation was performed by students at a dental school in Austria according to the working lengths obtained from the EAL. Subsequently, root apices (n=44) were longitudinally sectioned using a diamond coated bur. Measurements of the distance between the anatomical root apex (ARA) and the apical constriction (AC) as well as between ARA and the ascertained apical point of endodontic instrumentation were performed using digital photography and a 3D computer-assisted design software. The distance between ARA and the radiologic (ARA-R) or electrometric (ARA-EL) readings of the apical point of endodontic instrumentation was compared with the actual distance ARA-AC. The accuracy of both methods was determined. The difference between the actual distance ARA-AC and the targeted radiological distance was statistically significant (p=0.0001), as was the measured distance between ARA-R and ARA-EL (p=0.016). The electronic method seems to be more precisely referring to the AC (R(2)=0.0198) than the radiographic method (R(2)=0.0019). These results suggest that the endodontic simulation model described in this study can be successfully used in preclinical dental education.

Accuracy of an electronic apex locator in the retreatment of teeth obturated with plastic or cross-linked gutta-percha carrier-based materials: an ex vivo study.

INTRODUCTION: This ex vivo study evaluated the accuracy of the Root ZX electronic apex locator (EAL) (J Morita Corp, Kyoto, Japan) in determining the working length during retreatment of canals sealed with 2 different carrier-based obturating materials (ProTaper Obturator [Dentsply Maillefer, Ballaigues, Switzerland] and GuttaCore [Dentsply Maillefer]) and also evaluated whether they influenced its accuracy differently. METHODS: Fifty extracted single-rooted human teeth with sound apices were selected for the study. We measured canals with the direct visual technique using a #10 K-file and shaped them with ProTaper Universal instruments (Dentsply Maillefer) up to this predetermined length. After instrumentation, we determined the canal length again using the visual technique (direct length [DL]). This value was considered the "reference point." Specimens were then placed in a tooth holder (Pro-Train; Simit Dental, Mantova, Italy), and the canal length was electronically measured (electronic length 1 [EL1]). Specimens were then obturated with ProTaper Obturators (group 1, n = 25) and GuttaCore (group 2, n = 25). Seven days later, a new electronic length was determined (electronic length 2 [EL2]) during retreatment procedures in the presence of the obturating material. EL1 and EL2 values were compared with DL using the Bland and Altman method. The different influences of the tested materials on the accuracy of the EAL were calculated with repeated measures analysis of variance. RESULTS: Both EL1 and EL2 values provided a statistically significant overestimation of the actual canal length (DL [P < .05]), with the EL2 values higher from DL. The 2 different materials did not influence the accuracy of the EAL differently (P = .486). CONCLUSIONS: The measurements obtained with the EAL tested during orthograde retreatments can lead clinicians to overinstrumentation and consequent overfilling of the endodontic space.

Accuracy of three different apex locators and visual exam in primary teeth with and without root resorption in vitro.

AIM: The aim of this study was to evaluate the accuracy and reliability of three apex locators (EndoMaster, Raypex, DentaPort ZX) and visual assessment in primary molar teeth in vitro. MATERIALS AND METHODS: Twenty-four extracted human primary molar teeth with and without root resorption were used in this study. After endodontic access preparation, root canal length was visually measured by means of a K file; then the teeth were embedded into alginate and the roots were measured again by mans of the three apex locators. The results were collected in SPSS 15.0 and statistical evaluations were completed by one-way ANOVA and Kruksal-Wallis test. RESULTS: The measurements closest to the visually determined length were obtained with EndoMaster. No statistically significant differences were found between visual and apex locators lengths (p>0.05). CONCLUSION: Within the limitations of this study, the use of apex locators would be useful in the endodontic treatment of primary teeth.

Accuracy and repeatability of 3 apex locators in locating root canal perforations: an ex vivo study.

INTRODUCTION: This study was an ex vivo evaluation of the accuracy and repeatability of 3 electronic apex locators (EALs) in locating simulated root canal perforations. METHODS: Thirty-five human teeth were used. Perforations were placed 5 mm from the apex of each specimen. A #15 K-file was attached to a micrometer, and the specimens were fixed in a mounting model. The EALs were connected to the files, and electronic measurements of the simulated perforations were obtained. This procedure was repeated, the files were cemented in place, and x-rays were obtained to evaluate the distances between the measurement files and the simulated perforations. The obtained results were compared with the corresponding control lengths. Three investigators evaluated the distance of the file position in relation to the perforation for each specimen. The 3 investigators reached consensus regarding these measurements. RESULTS: Statistical analyses of the results revealed that the EAL reliabilities in the exact detections of the root canal perforations were 97.1% for the Mini Apex Locator, 100% for the Root SW, and 91.4% for the Root ZX II. Analysis of variance revealed that the accuracies of the 3 devices were not different (P > .05). The results also indicated high levels of repeatability for each of the 3 EALs (intraclass correlation coefficients: 0998, 0.999, and 0.999 for the Mini Apex Locator, Root SW, and Root ZX II, respectively). CONCLUSIONS: It was concluded that each of these 3 EALs provided excellent ex vivo accuracy in locating root perforations and that all tested devices possess excellent ex vivo repeatability.

Assessment of the separation incidence of reciprocating WaveOne files: a prospective clinical study.

INTRODUCTION: Despite metallurgical advancements in the nickel-titanium file manufacturing process, file separation remains a concern. The purpose of this prospective clinical study was to assess the separation incidence of the reciprocating WaveOne file (Dentsply Tulsa Dental Specialties, Tulsa, OK) when used to prepare root canals of posterior teeth. METHODS: File separation incidence was assessed over an 18-month period in which 4 experienced and calibrated endodontists performed conventional endodontic treatment on posterior teeth using the WaveOne file system. The separation incidence was determined based on both the number of teeth and the number of canals instrumented during this time period. RESULTS: A total of 2,215 canals (711 teeth) were treated. Three instruments (two 21.06 and one 25.08) separated during use and were deemed to be irretrievable. The overall instrument separation incidence in relation to the number of canals shaped was found to be 0.13% (0.42% teeth). CONCLUSIONS: Based on the results of this study, the incidence of endodontic instrument separation when using the WaveOne reciprocating file was considerably low.

Current trends in endodontic treatment by general dental practitioners: report of a United States national survey.

INTRODUCTION: In the United States almost 70% of root canal treatment (RCT) is performed by general dentists (GPs), yet little is known about their treatment protocols. METHODS: A paper survey was mailed to 2000 United States GPs with questions about the types of endodontic cases treated, routine treatment protocols, use of newer technologies, and endodontic continuing education (CE). RESULTS: Completed surveys were returned by 479 respondents (24%). GPs who perform RCT (84%) reported providing anterior (99%), bicuspid (95%), and molar (62%) RCT and retreatment (18%). Rubber dam was used always (60%), usually (16%), sometimes (13%), and never (11%). Newer technologies used by GPs included digital radiography (72%), magnification (80%), electronic apex locator (70%), and nickel-titanium rotary instrumentation (74%). Compared with GPs with >20 years of experience, those in practice for ≤10 years were more likely to use rubber dam (P < .05), nickel-titanium rotary instrumentation (P < .001), apex locators (P < .001), and magnification (P < .01); in contradistinction, GPs in practice >20 years were more likely to perform retreatments (P < .05). Women were less likely to perform retreatment or molar RCT (both P < .05). GPs with >5 hours of CE were more likely to use rotary instrumentation (P < .001), irrigant activation devices (P < .01), and apex locators (P < .001) and perform molar RCT (P < .001) and retreatment (P < .05), but no more likely to use rubber dam. CONCLUSIONS: Recent GP graduates (≤10 years) were more likely to adopt new technologies and use rubber dam than those who practiced for >20 years. More experienced GPs were more likely to take on complicated cases than those with fewer years of practice. There was no association between hours of CE and compliance with rubber dam usage.

Accuracy and reliability of working length determination by Gold Reciproc Motor in reciprocating movement.

INTRODUCTION: The purpose of this study was to assess the accuracy and reliability of the apex locator function of the Gold Reciproc Motor (VDW GmbH, Munich, Germany) during reciprocating movement. METHODS: Forty extracted incisors with mature apices were included in the study. The canal length was determined by introducing #10 file into the canal until it emerged at the apical foramen. The incisal edge of each tooth was adjusted to obtain 18 mm standard length and to produce a flat reference point. The teeth were embedded in Plexiglas tubes filled with alginate and measured by Root ZX (J. Morita Corp, Tokyo, Japan) and Bingo 1020 (Forum Engineering Technologies, Rishon Lezion, Israel) apex locators. The root canals were instrumented in a reciprocating mode using an R25 Reciproc file in the Gold Reciproc Motor until the green LEDs and orange LED were reached. According to the manufacturer, these LEDs represent the zone between the apical constriction and the apical foramen. RESULTS: No statistically significant differences were found between the length measurements of the 2 electronic apex locators and the third green LED, which is suggested by the manufacturers as the recommended working length. CONCLUSIONS: With the limitation of this ex vivo study, the Gold Reciproc Motor's integrated electronic apex locator was found to be as reliable and accurate as the Root ZX and Bingo 1020 apex locators in terms of length control during root canal preparation in the reciprocation mode.

Accuracy of the Dentaport ZX apex locator for working length determination when retreating molar root canals.

The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working length determination during root canal retreatment of mandibular molars. Fifteen extracted mandibular first molars with separate mesial canals and apical foraminae and one distal canal were selected. The mesiobuccal and distal canals were investigated; the length with the file tip at the major diameter was defined as the tooth length (TL). The canals were prepared with ProTaper files to 1 mm short of this and filled with gutta-percha and AH Plus sealer. One week later, the root fillings were removed using ProTaper retreatment files. Tooth length was remeasured and recorded as the retreatment tooth length (RTL). Then electronic measurements were taken at the major (electronic apex locator (EAL) major) and minor (EAL minor) foraminae as suggested by the instrument display. These lengths were compared with RTL and measurements 0.5 and 1 mm short of this distance. For both canals, no significant difference was found between RTL and EAL major, and 0.5 mm short of RTL and EAL minor (P > 0.05). There were significant differences found between all other readings. The Dentaport ZX could not detect the minor foramen accurately but was able to indicate the major foramen in molars undergoing a root canal retreatment procedure.

Influence of apical periodontitis on the accuracy of 3 electronic root canal length measurement devices: an in vivo study.

INTRODUCTION: The aim of this in vivo study was to evaluate the influence of apical periodontitis (AP) on the accuracy of Dentaport ZX (J Morita, Kyoto, Japan), Raypex 5 (VDW, Munich, Germany), and i-Root (S-Denti, Seoul, Korea) electronic root canal length measurement devices (ERCLMDs). METHODS: Thirty-two single-rooted teeth scheduled for extraction, consisting of 16 teeth with AP and 16 teeth with normal periapex (NP), were selected. The access cavity was prepared, and the coronal portion of the canal was flared. The electronic working length (EWL) was determined by each ERCLMD according to each manufacturer's instructions. Each tooth was extracted, and the actual working length (AWL) was determined by inserting a size 15 K-file until the tip could be seen at a position tangential to the major foramen and then 0.5 mm was subtracted from the measurement. The distance from the file tip (EWL) to the point 0.5 mm coronal to the major foramen (AWL) was calculated. Data were analyzed using the nonparametric Fisher exact test and the chi-square test. Statistical significance was set at P < .05. RESULTS: The accuracies of Dentaport ZX, Raypex 5, and i-Root within ± 0.5 mm in the AP group were 93.8%, 81.3%, and 75.0%; they were 93.3%, 86.7%, and 73.3% in the NP group, respectively. There were no significant differences between the accuracy of each device in the 2 groups (P > .05). Considering the 2 groups of AP and NP, there were no statistically significant differences in the accuracy of the ERCLMDs (P > .05). CONCLUSIONS: The presence of AP did not influence the accuracy of ERCLMDs.

An in vivo evaluation of different methods of working length determination.

OBJECTIVE: The purpose of this in vivo study was to compare the ability of digital tactile, digital radiographic and electronic methods to determine reliability in locating the apical constriction. MATERIALS AND METHODS: Informed consent was obtained from patients scheduled for orthodontic extraction. The teeth were anesthetized, isolated and accessed. The canals were negotiated, pulp chamber and canals were irrigated and pulp was extirpated. The working length was then evaluated for each canal by digital tactile sensation, an electronic apex locator (The Root ZX) and digital radiography. The readings were then compared with post-extraction working length measurements. RESULTS: The percentage accuracy indicated that EAL method (Root ZX) shows maximum accuracy, i.e. 99.85% and digital tactile and digital radiographic method (DDR) showed 98.20 and 97.90% accuracy respectively. CLINICAL SIGNIFICANCE: Hence, it can be concluded that the EAL method (Root ZX) produced most reliable results for determining the accurate working length.

Accuracy of electronic apex locator in enlarged root canals with different root canal irrigants: an in vitro study.

AIM: To evaluate the accuracy of Root ZX-II (J Morita Corp) apex locator in enlarged root canals with different root canal irrigants. MATERIALS AND METHODS: 48 freshly extracted single rooted mandibular premolar teeth were used. The apical enlargement was done up to #45 K-file as the master apical file (MAF). The teeth were randomly divided into 4 groups and mounted in an experimental apparatus. The following irrigants were used during electronic canal measurements: group 1: saline; group 2: 3% NaOCl; group 3: 2% chlorhexidine; group 4: 17% EDTA. The canal measurement was done with Root ZX-II apex locator using #10 and #45 K-file. Data were analyzed by two way ANOVA and Bonferroni multiple comparison test. RESULTS: Statistical analysis showed that there was statistically significant difference between #10 and #45 K-file for group 1 (p < 0.01). CONCLUSION: Root ZX-II was accurate in the presence of 3% NaOCl and 17% EDTA when measured with smaller and larger files. However, it was accurate in the presence of saline and 2% CHX when larger files were used.

Effect of chloroform, orange solvent and eucalyptol on the accuracy of four electronic apex locators.

The aim of this study was to evaluate the effect of three retreatment solutions on the accuracy of four electronic apex locators, the Root ZX mini, the Mini Apex Locator, the Root ZX and the Elements Diagnostic Unit and Apex Locator. Forty extracted single-rooted human teeth were used in this study. The four electronic apex locators were operated according to the manufacturer's instructions to locate the 'apical constriction' in the presence of chloroform, orange solvent or eucalyptol in the canal. The accuracy of each apex locator was not affected by the type of retreatment solution present in the root canal. In addition, the accuracy of the four apex locators was similar in the presence of each of the tested solutions.

Effects of multiple root canal usage on the surface topography and fracture of two different Ni-Ti rotary file systems.

AIM: The purpose of this study was to evaluate the effect of multiple root canal usage on the surface topography and fracture of Twisted File (TF) and ProTaper (PT) rotary Ni-Ti file systems, using scanning electron microscope (SEM). MATERIALS AND METHODS: Ten sets of PT and TF instruments were used to prepare the mesial canals of mandibular first molars. TF 25, 0.06 taper and PT F1 instruments were analyzed by SEM when new and thereafter every three root canal usages. This sequence was repeated for both the TF and PT groups until 12 uses. Two images of the instrument were recorded, one of the instrument tip and the other 5 mm from the tip, both at × 100 magnification. The sequential use was continued till the instrument fractured and the number of root canal usages for the file to fracture was noted. All fracture surfaces were examined under the SEM. RESULTS: Fresh TF instruments showed no surface wear when compared to PT instruments (P < 0.05). Spiral distortion scores remained the same for both the groups till the 6 th usage (P > 0.05), while at the 9 th usage TF showed a steep increase in the spiral distortion score when compared to PT (P < 0.05). PT instruments fractured at a mean root canal usage of 17.4, while TF instruments showed a mean root canal usage of 11.8. Fractographically, all the TF instruments failed due to torsion, while all the PT instruments failed because of cyclic fatigue. CONCLUSION: PT instruments showed more resistance to fracture than TF instruments.

A survey of endodontic practices among dentists in Nigeria.

AIM: To investigate the pattern of routine endodontic practices among Nigerian dentists. MATERIALS AND METHODS: This study was a questionnaire-based survey of samples of dentists in the Nigerian cities of Enugu and Benin. The self-administered questionnaire contained 25 close-ended questions with multiple choice options. The data collected included demographic details of respondents, root canal preparation techniques, irrigants and intracanal medicaments used, the number of appointments, method of working length determination, root filling techniques, cements used, and the scope of treatment performed. RESULTS: Most respondents used sodium hypochlorite as the irrigant, the step back technique for canal preparation, and lateral condensation with a zinc oxide-eugenol-based sealer for obturation. Most respondents did root canal treatment on all types of teeth and used radiographs to determine the working length 70% of the time. Most respondents followed up their patients for less than 12 months and most treated teeth with periapical areas larger than 10 mm by root canal therapy combined with apical surgery. CONCLUSION: Most Nigerian dentists use step back technique for canal preparation and lateral condensation for obturation. CLINICAL SIGNIFICANCE: Endodontic practice by Nigerian dentists differs from some established practice quality guidelines in many other countries, particularly in nonperfusion of modern techniques into practice, popularity of antibiotic use for endodontic emergencies and a high rate of perforations.

Suitability of time estimates for survival analysis of endodontic treatment.

INTRODUCTION: This study aimed to determine the most suitable estimates of the event date for Kaplan-Meier (K-M) survival analysis for the assessment of endodontic treatment outcomes. Survival probability computed using the Weibull accelerated failure time (WAFT) models based on interval-censored data was used for comparison. METHODS: A sample of root canal-treated teeth was included for survival analysis using the K-M and WAFT models. Treatment outcomes were categorized for the presence or absence of periapical healing and tooth survival. For the K-M analysis, the following time estimates between a visit when failure was diagnosed and the preceding visit were tested: the one-quarter point (T1), the half-way point (T2), the three-quarter point (T3), the date of diagnosis (T4), and the geometric mean (T5). RESULTS: The survival curve plotted from T2 consistently showed the least discrepancies in trend when compared against the WAFT curve. Those curves generated from T1 to T5 were significantly different from each other for periapical healing but not for tooth survival. CONCLUSIONS: T2 is the most reliable date for K-M analysis for measuring endodontic outcomes, especially when periapical healing is concerned. T4 would be a reasonable estimate for assessing tooth survival. Further research aiming at appropriate statistical exercise with simulations followed by proper goodness of fit tests should be considered.

Dental students' perceptions about the endodontic treatments performed using NiTi rotary instruments and hand stainless steel files.

This study evaluated the perceptions of Brazilian undergraduate dental students about the endodontic treatments performed using NiTi rotary instruments and hand stainless steel. Data were collected using a questionnaire administered to undergraduate dental students enrolled in endodontic disciplines. The students were divided into 3 groups: G1, students who had treated straight canals with SS hand instruments; G2, students who had treated curved canals with SS hand instruments; and G3, students who had treated both straight and curved canals with NiTi rotary instruments. The number of endodontic treatments performed, types of treated teeth, students' learning, time spent, encountered difficulties, quality of endodontic treatment and characteristics of the employed technique were analyzed. There was a 91.3% rate of return for the questionnaires. Mandibular molars were the most frequently treated teeth, followed by maxillary incisors. The Kruskal-Wallis test showed no differences in learning (p=0.528) or in the characteristics of the technique employed (p=0.560) among the three groups. G3 students performed a greater number of endodontic treatments (p<0.001) in a smaller time (p<0.001) than did G1 and G2 students. Difficulties were reported primarily by students in G2 and G3 compared with G1 (p=0.048). The quality of endodontic treatments differed only between G1 and G2 (p=0.045). The use of NiTi rotary instruments should be included in undergraduate dental curriculum, contributing to the increase of patients assisted and consequently to improve the clinical experience of the students.