Carlos Eduardo Fontana

In Vitro Evaluation of the Effectiveness of ProTaper Universal Rotary Retreatment System for Gutta-Percha Removal with or without a Solvent

INTRODUCTION Effective removal of gutta-percha in endodontic retreatment is a significant factor to ensure a favorable outcome from failed procedures. The purpose of this study was to evaluate the efficacy of a nickel-titanium rotary instrument system with or without a solvent versus stainless steel hand files for gutta-percha removal. METHODS Forty extracted human maxillary anterior teeth were prepared and filled. They were divided into 4 groups: Gates-Glidden and K-files, Gates-Glidden and K-files with chloroform, ProTaper Universal rotary retreatment system, and ProTaper Universal rotary retreatment system with chloroform. The operating time was recorded. The teeth were longitudinally sectioned and photographed. The images were analyzed and the filling remnants were quantified by using the IMAGE TOOL software. RESULTS With Kruskall-Wallis test, statistical analysis showed that there was no significant difference between the techniques in regard to the amount of the endodontic filling remnants (P < .05); however, the ProTaper Universal rotary retreatment system was faster than the hand files (P < .05). CONCLUSIONS All of the techniques proved helpful for the removal of endodontic filling material, and they were similar in material remaining after retreatment, but the ProTaper Universal rotary retreatment system without chloroform was faster.

Comparison among Manual Instruments and PathFile and Mtwo Rotary Instruments to Create a Glide Path in the Root Canal Preparation of Curved Canals

INTRODUCTION Nickel-titanium rotary instruments reduce procedural errors and the time required to finish root canal preparation. The goal of this study was to evaluate the occurrences of apical transportation and canal aberrations produced with different instruments used to create a glide path in the preparation of curved root canals, namely manual K-files (Dentsply Maillefer, Ballaigues, Switzerland) and PathFile (Dentsply Maillefer) and Mtwo (Sweden and Martina, Padua, Italy) nickel-titanium rotary files. METHODS The mesial canals of 45 mandibular first and second molars (with curvature angles between 25° and 35°) were selected for this study. The specimens were divided randomly into 3 groups with 15 canals each, and canal preparation was performed by an endodontist using #10-15-20 K-type stainless steel manual files (group M), #13-16-19 PathFile rotary instruments (group PF), and #10-15-20 Mtwo rotary instruments (group MT). The double digital radiograph technique was used, pre- and postinstrumentation, to assess whether apical transportation and/or aberration in root canal morphology occurred. The initial and final images of the central axis of the canals were compared by superimposition through computerized analysis and with the aid of magnification. The specimens were analyzed by 3 evaluators, whose calibration was checked using the Kendall agreement test. RESULTS No apical transportation or aberration in root canal morphology occurred in any of the teeth; therefore, no statistical analysis was conducted. CONCLUSIONS Neither the manual instruments nor the PathFile or Mtwo rotary instruments used to create a glide path had any influence on the occurrence of apical transportation or produced any canal aberration.

Influence of Coronal Restoration and Root Canal Filling Quality on Periapical Status: Clinical and Radiographic Evaluation

INTRODUCTION The purpose of this study was to evaluate the relationship between periapical status and the quality of coronal restoration and of root canal filling, assessed both clinically and radiographically, in a cohort of Brazilian patients. METHODS A total of 523 teeth from 337 patients submitted to endodontic treatment were clinically and radiographically reexamined 2-10 years postoperatively. Restoration and root canal filling quality were classified according to modified criteria from Tronstad et al. Periapical status was evaluated according to periapical index scores. Mann-Whitney and Friedman tests were used to conduct the descriptive analysis. Correlations were analyzed by using simple and multivariate logistic regression analysis. RESULTS No significant difference was observed between the rates of apical periodontitis for adequate or inadequate coronal restorations assessed clinically (12.8% versus 19.4%), whereas these rates were significantly different when the restoration quality was assessed radiographically (11.6% versus 28.7%, P < .001). The rates of apical periodontitis in teeth with inadequate root canal filling, with or without adequate restoration, were significantly higher than in teeth with adequate canal filling, with or without adequate restoration (38.6% and 48.4% versus 6.5% and 14.6%, respectively; P < .0001). CONCLUSIONS Using either a radiographic or clinical assessment alone was not a reliable method to ascertain whether restoration quality could be correlated with postoperative periapical status. Poor root canal filling quality was a prognostic determinant of endodontic treatment failure, whereas coronal restoration quality had a lesser impact on the outcome of the endodontic treatment.

Fracture Incidence of WaveOne and Reciproc Files during Root Canal Preparation of up to 3 Posterior Teeth: A Prospective Clinical Study

Introduction: Reciprocating instruments were developed to improve and simplify the preparation of the root canal system by allowing greater centralization of the canal and requiring a shorter learning curve. Despite the risk of instrument separation, using a reciprocating instrument in more than 1 case is a relatively common clinical practice. The aim of this study was to evaluate the fracture resistance of Reciproc (R25; VDW, Munich, Germany) and WaveOne (Primary; Dentsply Maillefer, Ballaigues, Switzerland) instruments according to the number of uses during the preparation of root canals in up to 3 posterior teeth. Methods: A prospective clinical study was conducted by 3 experienced specialists who performed treatment of 358 posterior teeth (1130 canals) over a period of 12 months using 120 reciprocating instruments, 60 of which were Reciproc R25 and 60 were WaveOne Primary. The motion used during instrumentation followed the recommendations of the respective manufacturers. After each use, the instruments were observed under a dental operating microscope at 8× magnification. In the case of fracture or deformation, the instrument was discarded. Results: None of the instruments showed any signs of deformation, but 3 instruments fractured (0.26% of the number of canals and 0.84% of the number of teeth). All fractures occurred in mandibular molars (1 WaveOne Primary file during the third use and 2 Reciproc R25 files, 1 during the first use and the other during the third use). Conclusions: There was a low incidence of fracture when reciprocating files were used in up to 3 cases of endodontic treatment in posterior teeth. HIGHLIGHTSReuse of reciprocating instruments in up to 3 cases of posterior teeth showed a low incidence of fracture.This fracture rate was comparable with that observed in previous studies on single‐use reciprocating instruments.This low instrument fracture rate was observed even though no cervical preflaring was performed.

Effects of Glide Path on the Centering Ability and Preparation Time of Two Reciprocating Instruments

Introduction: The aim of this in vitro study was to evaluate the effects of establishing glide path on the centering ability and preparation time of two single-file reciprocating systems in mesial root canals of mandibular molars. Methods and Materials: Sixty extracted mandibular molars with curvatures of 25-39 degrees and separate foramina for the mesiobuccal and mesiolingual canals, were divided into four groups (n=15); WaveOne+glide path; WaveOne; Reciproc+glide path and Reciproc. Non-patent canals were excluded and only one canal in each tooth was instrumented. A manual glide path was established in first and third groups with #10, 15 and 20 hand K-files. Preparation was performed with reciprocating in-and-out motion, with a 3-4 mm amplitude and slight apical pressure. Initial and final radiographs were taken to analyze the amount of dentin removed in the instrumented canals. The radiographs were superimposed with an image editing software and examined to assess discrepancies at 3-, 6- and 9-mm distances from the apex. The Kruskal-Wallis test was used for statistical analysis. The level of significance was set at 0.05. Results: Preparation in groups without glide paths was swifter than the other groups (P=0.001). However, no difference was observed regarding centering ability. Conclusion: Establishing a glide path increased the total instrumentation time for preparing curved canals with WaveOne and Reciproc instruments. Glide path had no influence on the centering ability of these systems.

Comparação entre os sistemas rotatórios Pathfile + Protaper Universal e Twisted Files quanto à preservação da morfologia e ao tempo de trabalho despendido na preparação de canais curvos

INTRODUCTION: Nickel-titanium (NiTi) rotary instruments reduce procedural errors and the time required for root canal preparation. The aim of this study was to compare two rotary NiTi instrumentation systems-Pathfile + ProTaper Universal versus Twisted Files-as to their ability to maintain original canal morphology and the time they require to prepare curved root canals. MATERIAL AND METHOD: The mesial canals of 32 human mandibular molars (with curvature angles between 20 and 40 degrees) were selected for the study, and divided at random into two groups of 16 canals each. The canals were prepared by an endodontist using either the combination of Pathfile and ProTaper Universal instruments (Group PT) or Twisted Files (Group TF). The double digital radiograph technique, pre- and post-instrumentation, was used by three endodontists to assess whether apical transportation and/or aberration in root canal morphology occurred. The initial and final images of the root canals were compared by superimposition through computerized analysis and with the aid of magnification. The odds ratio test was used to compare root canal morphology preservation, and ANOVA complemented by Tukeys test was used to compare preparation times. The significance level was set at 5%. RESULT: Deviation in root canal trajectory occurred in both groups, although the differences were not significant. The preparation time required by the Pathfile + ProTaper Universal combination was significantly longer than that required by the Twisted Files system. CONCLUSION: Both systems showed similar performances regarding the ability to maintain original root canal morphology; however, the preparation time required by the Twisted Files system was shorter

Foraminal Deformation after Foraminal Enlargement with Rotary and Reciprocating Kinematics: A Scanning Electronic Microscopy Study

Introduction: The aim of this study was to evaluate, under scanning electronic microscopy, the morphological aspect of apical foramen after root canal instrumentation with rotary and reciprocating kinematics at 2 different working length determinations. Methodology: Sixty mesiobuccal roots of mandibular and maxillary molars presenting with curvature ranging from 30 to 65° were used in this study. The roots were initially scanned with a scanning electronic microscope under ×50 magnification. Roots were divided into 2 different groups (n = 30): group 1 instrumented with rotary kinematics, and group 2 instrumented with reciprocating kinematics. Both groups were instrumented at 2 different working lengths: at the apex and 1 mm beyond the apex. The roots were scanned after the instrumentation at the apex and again after further instrumentation 1 mm beyond the apex. The photomicrographs obtained were assigned to 3 independent evaluators for foraminal deformation assessment through comparison with baseline images. Evaluators were masked with regard to the kinematics and working length used. The Pearson correlation test and Kruskal‐Wallis test (method of Dunn) were used for statistical analysis (P < .05). Results: The Pearson Correlation test showed good agreement among evaluators. Foraminal deformation was observed in instrumentation at the apex and 1 mm beyond the apex with both kinematics (P < .05). Conclusions: Within the limitations of this study, it can be concluded that root canal instrumentation at the apex or 1 mm beyond the apex promoted deformation of the major foramen, regardless of the kinematics. HighlightsForaminal enlargement is claimed to promote cleaning of the whole extension of root canal, which might improve outcomes especially in necrotic teeth.Single‐file reciprocating systems were launched to facilitate root canal instrumentation while maintaining root canal anatomy.Foraminal enlargement with both rotary and reciprocating systems at the apex or 1 mm beyond promoted foraminal deformation.

Smear Layer Removal Efficacy of Two Activated Irrigation Techniques After Reciprocating Instrumentation in Curved Canals

Introduction: This study aimed to compare the effectiveness of two activated irrigation techniques in removing the smear layer after single-file reciprocating instrumentation in curved canals. Materials and Methods: Sixty distobuccal roots of maxillary molars were standardized to create a closed system, and then instrumented using WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) instruments. Fifty-four specimens were randomly distributed into 3 groups for final irrigation: Non-activated irrigation, passive ultrasonic irrigation (PUI), and EndoActivator (EA;Dentsply Maillefer, Tulsa, USA) irrigation. All specimens received 3 mL of 17% EDTA for 1 minute, followed by irrigation with 6 mL of 2.5% NaOCl. The apical, middle and cervical thirds of the specimens were analyzed using scanning electronic microscopy (SEM), and the amount of remaining smear layer on the canal walls was rated by three examiners using a five-category scoring system. Kendall’s concordance coefficient was used to assess inter-rater agreement. Kruskal-Wallis and Mann-Whitney (Bonferroni) tests were used to compare the scores. Results: Kendall’s concordance coefficient was ≥ 0.7, indicating an excellent level of agreement between the raters. No statistically significant difference in irrigation techniques efficacy for removal of the smear layer (p=0.061) was found for the apical third. The scores attributed to the specimens irrigated with the EA system were significantly lower than those of the other groups in the cervical and middle thirds (p< 0.05). Conclusions: The efficacy of the EA system in removing the smear layer in the cervical and middle thirds of root canals instrumented with reciprocating motion was significantly higher than that of either PUI or non-activated irrigation. Both EA and PUI performed similarly in apical third.

In vivo assessment of accuracy of Propex II, Root ZX II, and radiographic measurements for location of the major foramen

Objectives The aim of this in vivo study was to assess the accuracy of 2 third-generation electronic apex locators (EALs), Propex II (Dentsply Maillefer) and Root ZX II (J. Morita), and radiographic technique for locating the major foramen (MF). Materials and Methods Thirty-two premolars with single canals that required extraction were included. Following anesthesia, access, and initial canal preparation with size 10 and 15 K-flex files and SX and S1 rotary ProTaper files, the canals were irrigated with 2.5% sodium hypochlorite. The length of the root canal was verified 3 times for each tooth using the 2 apex locators and once using the radiographic technique. Teeth were extracted and the actual WL was determined using size 15 K-files under a × 25 magnification. The Biostat 4.0 program (AnalystSoft Inc.) was used for comparing the direct measurements with those obtained using radiographic technique and the apex locators. Pearsons correlation analysis and analysis of variance (ANOVA) were used for statistical analyses. Results The measurements obtained using the visual method exhibited the strongest correlation with Root ZX II (r = 0.94), followed by Propex II (r = 0.90) and Ingles technique (r = 0.81; p < 0.001). Descriptive statistics using ANOVA (Tukeys post hoc test) revealed significant differences between the radiographic measurements and both EALs measurements (p < 0.05). Conclusions Both EALs presented similar accuracy that was higher than that of the radiographic measurements obtained with Ingles technique. Our results suggest that the use of these EALs for MF location is more accurate than the use of radiographic measurements.