Abstract Introduction This ex vivo study evaluated the disinfecting and shaping ability of 3 protocols used in the preparation of mesial root canals of mandibular molars by means of correlative ...bacteriologic and micro–computed tomographic (μμCT) analysis. Methods The mesial canals of extracted mandibular molars were contaminated with Enterococcus faecalis for 30 days and assigned to 3 groups based on their anatomic configuration as determined by μCT analysis according to the preparation technique (Self-Adjusting File ReDent-Nova, Ra’anana, Israel, Reciproc VDW, Munich, Germany, and Twisted File SybronEndo, Orange, CA). In all groups, 2.5% NaOCl was the irrigant. Canal samples were taken before (S1) and after instrumentation (S2), and bacterial quantification was performed using culture. Next, mesial roots were subjected to additional μCT analysis in order to evaluate shaping of the canals. Results All instrumentation protocols promoted a highly significant intracanal bacterial reduction ( P < .001). Intergroup quantitative and qualitative comparisons disclosed no significant differences between groups ( P > .05). As for shaping, no statistical difference was observed between the techniques regarding the mean percentage of volume increase, the surface area increase, the unprepared surface area, and the relative unprepared surface area ( P > .05). Correlative analysis showed no statistically significant relationship between bacterial reduction and the mean percentage increase of the analyzed parameters ( P > .05). Conclusions The 3 instrumentation systems have similar disinfecting and shaping performance in the preparation of mesial canals of mandibular molars.
Abstract Introduction This study evaluated the disinfecting ability of chemomechanical preparation with rotary nickel-titanium instruments, followed by 2 distinct adjunctive procedures in the root ...canals of extracted mandibular molars by means of a correlative analytical approach. Methods Twenty-two extracted mandibular molars were selected and anatomically matched between groups on the basis of micro–computed tomographic analysis. In the first phase of the experiment, root canals were contaminated with Enterococcus faecalis and subjected to chemomechanical preparation with BT RaCe instruments and 2.5% NaOCl irrigation. Then either XP-Endo Finisher instrument or passive ultrasonic irrigation was used to supplement disinfection. Micro–computed tomography was used to show whether the percentage of unprepared areas correlated to bacterial counts. In the second phase, the same teeth were contaminated once again, and the adjunctive procedures were used. Samples from the isthmus area of mesial roots and the apical 5-mm fragment of distal roots were obtained by cryopulverization. Samples taken before and after treatment steps in both phases were evaluated by quantitative polymerase chain reaction and statistically analyzed. Results In phase 1, preparation in both groups resulted in substantial decrease of bacterial counts ( P < .001). The adjunctive approaches led to a further small bacterial reduction, which was significant for XP-Endo Finisher ( P < .05). No significant differences were observed between groups for persisting bacterial counts. Correlative analysis revealed no statistically significant relationship between bacterial reduction and the percentage of unprepared areas ( P > .05). In phase 2, both methods had significant antibacterial effects in the main canal, but none of them could predictably disinfect the isthmus/recess areas. Conclusions Both XP-Endo Finisher and passive ultrasonic irrigation exhibited antibacterial effectiveness, but only the former caused a significant reduction in the bacterial counts after chemomechanical preparation. None of them were effective in predictably disinfecting the isthmus/recess areas.
Abstract Introduction The purpose of this ex vivo study was to evaluate the percentage reduction of accumulated hard tissue debris (AHTD) in the mesial root canal system of mandibular molars under ...different final irrigation regimens by means of micro–computed tomographic imaging. Methods Sixty curved mesial roots of mandibular molars with 2 independent canals joint apically by an isthmus (Vertucci type II) were selected. Specimens were scanned at a resolution of 12.5 μm, anatomically matched, and distributed into 3 groups ( n = 20) according to the preparation protocol: Self-Adjusting File (SAF; ReDent Nova, Ra'anana, Israel), Reciproc (VDW GmbH, Munich, Germany), and Revo-S (Micro-Mega, Besançon, France) systems. Then, each group was subdivided into 2 subgroups ( n = 10) according to the final irrigation protocol with the SAF or EndoVac system (Discus Dental, Culver City, CA). The percentage volume and percentage reduction of AHTD after root canal preparation and final irrigation protocols were statistically compared using 1-way analysis of variance, the paired sample and the independent Student's t tests. The level of significance was set at 5%. Results Within groups, the mean percentage volume was significantly reduced after the final irrigation procedures in either the SAF (from 1.52%–1.78% to 1.01%–1.20%) or EndoVac (from 2.11%–2.23% to 1.31%–1.52%) subgroups ( P < .05). In the experimental groups, the mean percentage reduction of AHTD ranged from 29.15%–39.90% after the irrigation protocols, with no statistical difference between groups ( P > .05). Conclusions None of the irrigation approaches succeeded in rendering the mesial root canal system free of AHTD. A similar percentage reduction of AHTD was achieved after final irrigation protocols using either the SAF or EndoVac system.
Abstract Introduction The accumulation of debris occurs after root canal preparation procedures specifically in fins, isthmus, irregularities, and ramifications. The aim of this study was to present ...a step-by-step description of a new method used to longitudinally identify, measure, and 3-dimensionally map the accumulation of hard-tissue debris inside the root canal after biomechanical preparation using free software for image processing and analysis. Methods Three mandibular molars presenting the mesial root with a large isthmus width and a type II Vertucci's canal configuration were selected and scanned. The specimens were assigned to 1 of 3 experimental approaches: (1) 5.25% sodium hypochlorite + 17% EDTA, (2) bidistilled water, and (3) no irrigation. After root canal preparation, high-resolution scans of the teeth were accomplished, and free software packages were used to register and quantify the amount of accumulated hard-tissue debris in either canal space or isthmus areas. Results Canal preparation without irrigation resulted in 34.6% of its volume filled with hard-tissue debris, whereas the use of bidistilled water or NaOCl followed by EDTA showed a reduction in the percentage volume of debris to 16% and 11.3%, respectively. The closer the distance to the isthmus area was the larger the amount of accumulated debris regardless of the irrigating protocol used. Conclusions Through the present method, it was possible to calculate the volume of hard-tissue debris in the isthmuses and in the root canal space. Free-software packages used for image reconstruction, registering, and analysis have shown to be promising for end-user application.
Abstract Introduction This study aimed to evaluate the frequency of dentinal microcracks observed after root canal preparation with 2 reciprocating and a conventional full-sequence rotary system ...using micro–computed tomographic analysis. Methods Thirty mesial roots of mandibular molars presenting a type II Vertucci canal configuration were scanned at an isotropic resolution of 14.16 μm. The sample was randomly assigned to 3 experimental groups ( n = 10) according to the system used for the root canal preparation: group A—Reciproc (VDW, Munich, Germany), group B—WaveOne (Dentsply Maillefer, Baillagues, Switzerland), and group C—BioRaCe (FKG Dentaire, La-Chaux-de-Fonds, Switzerland). Second and third scans were taken after the root canals were prepared with instruments sizes 25 and 40, respectively. Then, pre- and postoperative cross-section images of the roots ( N = 65,340) were screened to identify the presence of dentinal defects. Results Dentinal microcracks were observed in 8.72% ( n = 5697), 11.01% ( n = 7197), and 7.91% ( n = 5169) of the cross-sections from groups A (Reciproc), B (WaveOne), and C (BioRaCe), respectively. All dentinal defects identified in the postoperative cross-sections were also observed in the corresponding preoperative images. Conclusions No causal relationship between dentinal microcrack formation and canal preparation procedures with Reciproc, WaveOne, and BioRaCe systems was observed.
Abstract Introduction The aim of this study was to evaluate the morphologic aspects of the root canal anatomy of the distal root of a mandibular first molar using micro–computed tomographic analysis. ...Methods One-hundred distal roots of mandibular first molars were scanned using a micro–computed tomographic device at an isotropic resolution of 19.6 μm. The percentage frequency distribution of the morphologic configuration of the root canal was performed according to the Vertucci classification system. Two-dimensional parameters (area, perimeter, roundness, aspect ratio, and major and minor diameters) and the cross-sectional shape of the root canal were analyzed in the apical third at every 1-mm interval from the main apical foramen in roots presenting Vertucci types I and II configurations ( n = 79). Data were statistically compared using the Kruskal-Wallis and Dunn tests with a significance level set at 5%. Results Seventy-six percent of the distal roots had a single root canal. Two, three, and four canals were found in 13%, 8%, and 3% of the sample, respectively. In 13 specimens, the configuration of the root canal did not fit into Vertucci's classification. Overall, 2-dimensional parameter values significantly increased at the 3-mm level ( P < .05). The prevalence of oval canals was higher at the 1-mm level and decreased at the 5-mm level in which long oval and flattened canals were more prevalent. Conclusions The distal roots of the mandibular first molars showed a high prevalence of single root canals. The prevalence of long oval and flattened canals increased in the coronal direction. In 13% of the samples, canal configurations that were not included in Vertucci's configuration system were found.
Abstract Introduction This study aimed to describe the anatomy of mandibular central and lateral incisors using micro–computed tomographic imaging. Methods One hundred mandibular incisors were ...scanned in a micro–computed tomographic device using an isotropic resolution of 22.9 μm. The anatomy of each tooth (length of the roots, presence and location of accessory canals and apical deltas, and number of canals) as well as the 2- and 3-dimensional morphologic aspects of the canal (area, roundness, diameter, volume, surface area, and structure model index) were evaluated. Data were statistically compared using the Student t test (alpha = 0.05). Results The mean lengths of the mandibular central and lateral incisors were 20.71 and 21.56 mm, respectively. Most of the central (60%) and lateral (74%) incisors had no accessory canals. An apical delta was observed in only 1 specimen. The cross-section analysis of the apical third showed the presence of 1, 2, or 3 canal orifices. No statistical difference was observed in the comparison of the 2- and 3-dimensional morphologic parameters between central and lateral incisors ( P < .05). The qualitative analyses of the 3-dimensional models of the root canal systems of the central and lateral incisor teeth confirm that the most prevalent configurations were Vertucci's types I (50% and 62%, respectively) and III (28%). Conclusions Overall, mandibular central and lateral incisors were similar in terms of the 2- and 3-dimensional analyzed parameters. Vertucci's types I and III were the most prevalent canal configurations of the mandibular incisors; however, 8 new types have also been described.
Abstract Introduction The aim of the present study was to evaluate the frequency of dentinal microcracks observed after root canal preparation with ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, ...Switzerland) and Twisted File Adaptive (TFA; SybronEndo, Orange, CA) systems through micro–computed tomographic analysis. Methods Twenty moderately curved mesial roots of mandibular molars presenting a type II Vertucci canal configuration were randomly assigned to 2 experimental groups ( n = 10) according to the system used for the root canal preparation: PTN or TFA systems. The specimens were scanned through high-resolution micro–computed tomographic imaging before and after root canal preparation. Afterward, pre- and postoperative cross-sectional images of the mesial roots ( N = 25,820) were screened to identify the presence of dentinal defects. Results Dentinal microcracks were observed in 38.72% ( n = 5150) and 30.27% ( n = 3790) of the cross-sectional images in the PTN and TFA groups, respectively. All dentinal defects identified in the postoperative scans were already present in the corresponding preoperative images. Conclusions Root canal preparation with PTN and TFA systems did not induce the formation of new dentinal microcracks.
Abstract Introduction The newly developed single-file systems claimed to be able to prepare the root canal space with only 1 instrument. The present study was designed to test the null hypothesis ...that there is no significant difference in the preparation of oval-shaped root canals using single- or multiple-file systems. Methods Seventy-two single-rooted mandibular canines were matched based on similar morphologic dimensions of the root canal achieved in a micro–computed tomographic evaluation and assigned to 1 of 4 experimental groups ( n = 18) according to the preparation technique (ie, Self-Adjusting File ReDent-Nova, Ra’anana, Israel, WaveOne Dentsply Maillefer, Ballaigues, Switzerland, Reciproc VDW, Munich, Germany, and ProTaper Universal Dentsply Maillefer systems). Changes in the 2- and 3-dimensional geometric parameters were compared with preoperative values using analysis of variance and the post hoc Tukey test between groups and the paired sample t test within groups (α = 0.05). Results Preparation significantly increased the analyzed parameters; the outline of the canals was larger and showed a smooth taper in all groups. Untouched areas occurred mainly on the lingual side of the middle third of the canal. Overall, a comparison between groups revealed that SAF presented the lowest, whereas WaveOne and ProTaper Universal showed the highest mean increase in most of the analyzed parameters ( P < .05). Conclusions All systems performed similarly in terms of the amount of touched dentin walls. Neither technique was capable of completely preparing the oval-shaped root canals.
Abstract Introduction This study compared the amount of hard tissue debris produced after different apical enlargement with single-file reciprocating systems (WaveOne Dentsply Maillefer, Baillaigues, ...Switzerland and Reciproc VDW, Munich, Germany) and a conventional multifile rotary system (BioRaCe FKG Dentaire, La-Chaux-de-Fonds, Switzerland) using micro–computed tomographic imaging. Methods Thirty moderately curved mesial roots of mandibular molars presenting 2 independent root canals were selected and scanned at an isotropic resolution of 14.16 μm. The sample was assigned to 3 groups ( n = 10) with respect to the root length and degree of curvature of the mesial root according to the system used for the root canal preparation: Reciproc, WaveOne, and BioRaCe. Second and third scans were taken after the root canals were prepared up to ISO sizes 25 and 40, respectively. The matched images of the mesial canals, before and after preparation, were examined from the furcation level to the apex to evaluate the amount of hard tissue debris (%). Data were statistically compared using a general linear model for repeated-measures with a significance level set at 5%. Results Instrumentation systems per se did not influence the amount of hard tissue accumulation ( P > .05), whereas a significant reduction in the percentage of hard tissue debris was observed after sequential enlargement in all groups ( P < .05). Conclusions None of the systems yielded root canals completely free from packed hard tissue debris. The increased final apical size resulted in significantly less debris accumulation for both reciprocating and rotary systems.
