Marcelo Santos Coelho

Light-emitting diode assessment of dentinal defects: the role of presumed extraction forces.

Objectives The evaluation of iatrogenic dentinal defects in extracted teeth may be influenced by extraction forces and prolonged dry times. The purpose of this study was to compare the presence of dentinal defects in freshly extracted, periodontally compromised teeth with those in a group of teeth with uncontrolled extraction forces and storage time. Materials and Methods The experimental group consisted of eighteen roots obtained from teeth extracted due to periodontal reasons with class II or III mobility. They were kept in saline and sectioned within 1 hour following extraction. The control group consisted of matched root types obtained from an anonymous tooth collection, consistent with previous dentinal defect studies. The slices were obtained at 3, 6, and 9 mm from the apex. The imaging process exposed all specimens to no more than 60 seconds of dry time. The × 12.8 magnification was used for the 9 mm slices and × 19.2 magnification for the 3 mm and 6 mm slices under light-emitting diode (LED) transillumination. The root canal spaces and periodontal tissues were masked to minimize extraneous factors that might influence the evaluators. Chi-square test was used for statistical analysis. Results Dentinal defects were detected in 17% of the experimental group teeth, compared to 61% of control teeth (p = 0.015). Conclusions LED transillumination assessment of freshly extracted roots with class II or III mobility showed smaller number of dentinal defects than roots with uncontrolled storage time and extraction forces. The use of freshly extracted roots with mobility should be considered for future dental defect assessment studies.

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.

Separation of Nickel-Titanium Rotary and Reciprocating Instruments: A Mini-Review of Clinical Studies

Objective: This review aimed to evaluate clinical studies that assessed separated NiTi rotary and reciprocating instruments. Design and Methods: This review assessed clinical studies involving treatments performed by undergraduate students, graduate students, and endodontic specialists. This review evaluated studies using rotary instruments, reciprocating instruments, and hybrid techniques. The number of uses of the different NiTi rotary and reciprocating systems was also assessed. Results: The incidence of separation for rotary instruments ranged from 0% to 23%. Rotary instruments were used from 1 to 50 times depending on the instrument and tooth type. The lowest rate of incidence separation for rotary instruments was obtained by undergraduate students, using a hybrid technique. The separation incidence for reciprocating instruments ranged from 0% to 1.71%. Reciprocating instruments were mostly single-used; one study reported their use up to 3 times. Separation rate in reciprocating instruments was similar in single-use or in multiple uses 0.2%. Conclusions: Separation of instruments has dropped recently and seems to be a minor problem in current Endodontics. Multiple uses of NiTi rotary instruments are a possibility without significantly increasing the risk of instrument separation. Single and multiple uses of NiTi reciprocating instruments are also associated with low incidence of separation. Attempting to remove separated instruments should be carefully evaluated.

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.

Locating the second mesiobuccal canal in maxillary molars: challenges and solutions

The second mesiobuccal canal in mesiobuccal roots in maxillary molars is a common finding in root canal treatments. Failure on the location of these canals is associated with a high rate of unsuccessful treatments of maxillary molars. Its prevalence has been assessed in several in vitro and in vivo studies, presenting variations according to the methodology applied, along with the population of interest. While the anatomy of these teeth is well defined in micro-computed tomography studies, the clinical management is a great challenge for the practitioner. The use of a dental operating microscope has rendered a better clinical outcome when considering the location and treatment of this canal. On the other hand, cone-beam computed tomography use is still controversial in the efficacy of MB2 canal location. The association of a dental operating microscope with troughing performed with ultrasonic tips is an essential step in this location. Moreover, sodium fluorescein might be applied for root canal location. Due to the high rate of unsuccessful cases when the MB2 canal is not initially found, several cases are performed aiming to address the cases of missed MB2 canals. Therefore, the clinician should discuss the best possible approach, whether surgical or clinical. This article presents an overview of the importance of the MB2 canal on the outcomes of root canal treatments of maxillary molars. Solutions based in current literature will be presented accordingly.

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.

Influence of Passive Ultrasonic Irrigation on the Removal of Root Canal Filling Material in Straight Root Canals

Objective: This study evaluates the efficacy of passive ultrasonic irrigation (PUI) in removing root canal filling material from endodontically treated teeth after using one of two reciprocating systems, Reciproc (VDW, Munich, Germany) or WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), or one nickel-titanium (NiTi) rotary system, ProTaper Universal Retreatment (Dentsply Maillefer). Methods: One hundred and twenty straight root canals of extracted human maxillary incisors were instrumented and then obturated. The specimens were divided into six groups (n=20) as follows: Group R, Reciproc R25 instrument without PUI; Group W, WaveOne Primary instrument without PUI; Group PT, ProTaper Universal Retreatment system without PUI; Group R-PUI, Reciproc R25 with PUI; Group W-PUI, WaveOne Primary with PUI and Group PT-PUI, ProTaper Universal Retreatment system with PUI. After removing the filling material, the teeth were cleaved longitudinally and photographed. The total canal space and remaining material were quantified with the aid of an imaging software tool. The Kruskal-Wallis test was used to identify significant differences between the groups. Results: No statistically significant differences (P>0.05) in residual filling material were observed between the groups. Conclusion: The use of PUI did not improve the removal of filling material from the root canals, regardless of the previously used instrumentation system.

Nominal Size and Taper Analysis of Novel Metallurgy NiTi Files

Objective: The aim of this investigation was to assess the nominal tip diameter, taper and true pilot tip length of three nickel-titanium (NiTi) rotary files before and after use. Methods: Three brands of NiTi files of size 25.08 were evaluated: ProTaper Uni-versal (Dentsply Tulsa Specialties, Tulsa, USA), Channels PT (Insight Endo for Henry Schein, Melville, NY) and ProTaper Gold (Dentsply Tulsa Specialties), with ten files from each brand (total n=30). Scanning electron microscope (SEM) images of the files at 50x magnification were acquired before and after the files were used on endodontic training blocks, and the images were analysed by two independent investigators using ImageJ software. The nominal tip diameter (D0), taper and true pilot tip length (measured as the distance from the advertised diameter size of the file to the tip of the file) were recorded for each file and were analysed for statistical differences using repeated measures of analysis of variance (r-ANOVA) and Tukey’s post-hoc test (P<0.05). Results: The marginal means of the nominal size showed statistically significant differences between brands of the same size; statistically significant differences were also observed between the advertised sizes and the actual sizes (P<0.001). The mean taper values showed statistically significant differences from the advertised (p<0.001) sizes, except for the ProTaper Gold (P=0.023) group. The changes in the true pilot tip length before and after use were not statistically significant (P>0.05). The pilot tip lengths varied between brands. Conclusion: All nominal tip diameters and most taper sizes of the analysed brands show statistically significant differences from the nominal sizes advertised by the manufacturers. The differences in true pilot tip lengths between brands indicate a current lack of standardization.