Impact of needle insertion depth on the removal of hard-tissue debris

Can the addition of surfactants to NaOCl irrigation impact on the percentage of voids of root canal filling?

This study evaluated the impact of canal irrigation using surfactants associated to NaOCl on the percentage of voids of root canal filling through micro-computed tomographic (micro-CT) analysis. 27 mandibular mesial roots with Vertucci type II canal configuration with isthmus were selected and scanned in a micro-CT device. The specimens were assigned to three groups (n = 9), according to the irrigation solution during instrumentation: 2.5% NaOCl without additives (control), 2.5% NaOCl with 0.1% Benzalkonium Chloride and 2.5% NaOCl with 0.1% Tween 80. After obturation, the specimens were rescanned, and the percentage of voids were calculated. Data were analysed using one-way ANOVA with a significance level of 5%. The percentage of voids were similar among the groups (p > 0.05). None of the specimens showed completely voids-free areas. The addition of surfactants to NaOCl irrigation did not improve the quality of root canal filling of mandibular mesial root canals.

Syringe irrigation in confluent canals: A sequential computational fluid dynamics assessment

This study aims to assess the influence of root canal preparation, irrigation needle design and its placement depth in the irrigation flow of confluent canals during syringe irrigation. A mandibular molar presenting two confluent canals in its mesial root was sequentially prepared and scanned by micro-computed tomography after mechanical preparation up to ProTaper Next system sizes X2 (25/.06v), X3 (30/.07v) and X4 (40/.06v). In each of the root canal preparation models, a side-vented and an open-ended needle at 5, 3 and 2 mm from the working length were included, and irrigation flow was assessed by a validated computational fluid dynamics model. The results revealed that the irrigant flowed out of the confluent canals mainly through the canal that did not have the needle. Apical penetration and renewal of the irrigant were most efficiently achieved with the use of a 30G open-ended needle and a 30/.07v preparation.

Enhancing debris removal in curved canals: a comparative evaluation of XP-endo Finisher and Passive Ultrasonic Irrigation

OBJECTIVES

The study aimed to compare the efficacy of XP-endo Finisher and Passive Ultrasonic Irrigation (PUI) in removing hard tissue debris from curved canals.

MATERIALS AND METHODS

Thirty-four mandibular molars with Vertucci's type II mesial canals were scanned in microcomputed tomography before and after preparation with HyFlex EDM, and accumulated hard tissue debris was quantified. Subsequently, the teeth were randomly divided into two groups according to the supplementary procedure: PUI with the Ultra-X insert or XP-endo Finisher. After the intervention, the specimens underwent another scanning. Two separate analyses were conducted, one for the total canal and another for the isthmus area. Unpaired and paired T-tests were used for inter- and intergroup comparisons, with a significance level set at 5%.

RESULTS

Both supplementary methods reduced the amount of debris compared to the initial volume. Remarkably, the XP-endo Finisher achieved a significantly higher percentage of debris removal (71% for the total canal and 74% for the isthmus areas) compared to PUI (41% for the total canal and 52% for the isthmus area) (P < 0.05).

CONCLUSIONS

Both supplementary approaches reduced the amount of hard tissue debris from canal preparation, still XP-endo Finisher showed a higher reduction compared to PUI (p < 0.05).

CLINICAL RELEVANCE

None of the supplementary methods rendered canals completely free of hard tissue debris. However, the supplementary approach with XP-endo Finisher resulted in lower levels of hard tissue debris than PUI in curved canals with isthmuses.

XP-endo Finisher effectively reduces hard-tissue debris accumulated in root canals with isthmus after preparation with a reciprocating file system

This study compared the accumulated hard-tissue debris (AHTD) after preparation with WaveOne Gold (WOG) to XP-endo Shaper (XPS), without and with a supplementary step using XP-endo Finisher (XPF) using clinically applicable irrigation. Twenty-four mesial roots with two canals and single foramen were micro-CT-scanned and matched. Scans were also taken after preparation with WOG or XPS, and after XPF. Irrigation with 2.5% NaOCl (total: 17 ml per canal) and 17% EDTA (2.5 ml per canal) was performed using a 30ga Max-I-Probe needle placed up to the working length. Morphological parameters were calculated and compared within and among groups. XPF significantly reduced unprepared area within XPS and WOG groups, and AHTD within WOG (p < 0.05). There were no significant differences between WOG and XPS after preparation and after XPF (p > 0.05). In conclusion, WOG and XPS produced a similar volume of AHTD, but the supplementary step with XPF decreased the AHTD in the WOG group.

Effect of preparation size on the removal of accumulated hard-tissue debris from the mesial root canal system of mandibular molars using SWEEPS technology

OBJECTIVES

This study assessed the influence of preparation size on the efficacy of shock wave-enhanced emission photoacoustic streaming (SWEEPS) and conventional irrigation (CI) on removal of accumulated hard tissue debris (AHTD) from isthmus-containing mandibular molars using micro-computed tomographic analysis.

MATERIALS AND METHODS

Sixty extracted mandibular molars with two mesial canals connected by an isthmus were selected. Canals were shaped with Mtwo instruments (VDW, Munich, Germany) up to sizes 25/.06, 40/.04 or 40/.06 (n = 20), and specimens were distributed into 2 final irrigation groups (n = 10): SWEEPS and CI. Roots were scanned at a resolution of 10.5 µm before and after preparation and final irrigation. Data sets were co-registered, and the percentage reduction of AHTD calculated for each specimen was statistically compared using analysis of variance with a of 5% significance level.

RESULTS

The preparation size did not significantly influence the percentage reduction of AHTD (p < 0.05), whereas the final irrigation technique had a significant effect on debris removal (p < 0.05). A significant reduction of AHTD was achieved after final irrigation in all groups (p < 0.05); however, SWEEPS was associated with a significantly greater percentage reduction of debris than CI (p < 0.05). None of the specimens presented a completely clean isthmus.

CONCLUSIONS

Removal of AHTD was not significantly affected by the preparation size. SWEEPS was associated with significantly less debris than CI.

CLINICAL RELEVANCE

SWEEPS performed significantly better than CI regarding the removal of AHTD from isthmus-containing mandibular molars irrespective of the preparation size.

Micro-CT evaluation of four final irrigation protocols on hard-tissue debris removal from mesial roots of mandibular molars containing isthmus

OBJECTIVES

To evaluate by means of microcomputed tomography (micro-CT), the efficacy of four final irrigation protocols in the removal of hard-tissue debris (HTD) in mesial roots of mandibular molars containing isthmus.

MATERIALS AND METHODS

Forty standardized mesial roots of extracted mandibular molars presenting isthmus were selected. The root canals were prepared and randomly divided into 4 groups (n = 10): EA, EndoActivator (Dentsply Sirona); EC, Easy Clean (Easy Dental Equipment, Belo Horizonte, Brazil); XPF, XP-Endo Finisher (FKG Dentaire, La Chaus-de Fonds, Switzerland); and PUI, passive ultrasonic irrigation using Irrisafe tip (Satelec Acteon, Merignac, France). Each final irrigation protocol was performed in two cycles (60 s), using, respectively, 2.5% sodium hypochlorite and 17% EDTA. Micro-CT scans were obtained pre-operatory, post-preparation, and post-irrigation. The percentage of HTD reduction was calculated. Data was analyzed statistically (ANOVA and Kruskal-Wallis, significance set at 5%).

RESULTS

The percentage of HTD reduction was greatest for the XPF group (77.92%), followed by EA (62.92%), PUI (47.48%), and EC (32.65%). Statistical differences (p < .05) were found between XPF and EC only. A significant difference (p < .05) was found between XPF and EC in all thirds and between PUI and EC in the middle third.

CONCLUSIONS

XPF, EA, and PUI were similarly effective in HTD reduction. However, none of the evaluated protocols was able to completely remove all the debris.

CLINICAL RELEVANCE

Final irrigation protocols aim to clean the canal complexities that are not addressed by the shaping procedures. Micro-CT allowed to assess the removal of hard-tissue debris in the isthmus and canals of mandibular molars.

A critical analysis of research methods and experimental models to study irrigants and irrigation systems

Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro-computed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics.

A Novel Digital Technique to Analyze the Wear of CM-Wire NiTi Alloy Endodontic Reciprocating Files: An In Vitro Study

The present study seeks to describe a novel digital measurement technique for analyzing the wear volume of controlled memory (CM)-wire NiTi alloy endodontic reciprocating files after clinical use. Material and Methods: Ten CM-wire NiTi endodontic reciprocating files were randomly used in ten first upper molar teeth within four root canals. The CM-wire NiTi alloy endodontic reciprocating files were subjected to preoperative and postoperative micro-computed tomography (micro-CT) scans to obtain accurate digital imaging and communication on medicine (DICOM) digital files, which were segmented using intensity-based thresholding and an exclusive OR (XOR) logical operation (Boolean algebra logical operator) to obtain a mask of the location to localize and quantify the wear volume of the CM-wire NiTi alloy endodontic reciprocating files. Gage repeatability and reproducibility statistical analysis was applied to assess the reproducibility and repeatability of this measurement technique. Results: The analysis showed a repeatability and reproducibility of 0.00% for the digital measurement technique used to analyze the wear volume of CM-wire NiTi alloy endodontic reciprocating files after clinical use. Wear was mostly identified at the tip and cutting edges of the CM-wire NiTi alloy endodontic reciprocating files. Conclusions: This novel digital measurement technique is a repeatable, reproducible, and accurate method of quantifying the wear volume of CM-wire NiTi alloy endodontic reciprocating files after clinical use.

Effect of passive ultrasonic irrigation on hard tissue debris removal: a systematic review and meta-analysis

Accumulated hard tissue debris (AHTD) in root canal irregularities may negatively impact adequate root canal disinfection. In light of this, the efficacy of passive ultrasonic irrigation (PUI) to reduce AHTD has been largely studied in in vitro studies, which have adopted different analytic methods of varying accuracy to determine the extent of AHTD more correctly. Therefore, the aim of this study was to compare how well PUI and non-activated irrigation (NAI) systems perform in reducing AHTD during final irrigation protocols, based exclusively on studies whose analyses used microCT scanning. A systematic search of the studies published up to April 2020 was performed using MeSH terms and free terms, in the following databases: PubMed, Scopus, Web of Science, BVS (Lilacs and BBO) and Embase. The inclusion criteria consisted of laboratory studies that evaluated the amount of AHTD, and compared PUI with NAI protocols using microCT analysis. The risk of bias in the selected studies was assessed critically by two reviewers. A meta-analysis was performed using the RevMan software program (P<0.05), and included studies providing the standardized mean difference (SMD), using a fixed effect model, and adopting a confidence interval of 95%. In all, 3495 studies were identified, three of which met the inclusion criteria. All three were considered as having a low risk of bias. The meta-analysis comparing the ability of PUI and NAI protocols to remove hard tissue debris showed a higher percentage of AHTD reduction (P<0.01) for PUI, with a confidence interval of 1.41 [0.79, 2.02]. The heterogeneity among the studies was 82% (I2). Considering the limitations of the present study, this systematic review and meta-analysis showed that PUI was more effective than NAI in removing hard tissue debris, based exclusively on studies that used microCT scanning to provide a more precise analysis of the two techniques used. The findings presented in the present study reinforce the concept that PUI can increase residue removal and improve the cleanliness of the root canal in endodontic treatments.

Examination of Irrigant Flow on a Tooth With Internal Root Resorption by Using a Computational Fluid Dynamics Model

Objective:

This study investigated the flow of an endodontic irrigant in a single-rooted tooth with internal root resorption (IRR).

Methods:

A simulation of a prepared central incisor with internal root resorption was created and irrigation with a 30-G needle was performed. The fluid pattern of the irrigant was evaluated using a Computational Fluid Dynamics model. In addition, the effects of the needle-insertion depth in the root canal and the size of root resorption on the fluid flow and the wall shear stress (WSS) values were assessed. The IRR was placed immediately below the canal orifice.

Results:

Inadequate irrigant washout was observed inside the resorption cavity when the needle was positioned 1 mm from the working length while placing the needle slightly above the resorption cavity resulted in significant irrigant circulation inside the resorption cavity. Moreover, when the needle was placed slightly above the defect, the calculated WSS values in the resorption cavity walls were significantly higher (approximately 20 times higher in every case). In cases where the needle was placed 1 mm from the working length, the average and maximum WWS values were between 3 Pa and 51 Pa, while in cases where the needle was placed coronal to the IRR, the values were between 55 Pa and 528 Pa. The radius of the resorption cavity did not affect the irrigant flow patterns.

Conclusion:

During the endodontic treatment of cases with internal root resorption, complementary irrigations with the needle tip placed slightly above the resorption cavity should be followed to better debride the root canal.

Efficacy of Handpiece Mounted Continuous Irrigation System for the Removal of Residual Pulpal Debris During Root Canal Preparation

Objective  The removal of residual pulpal debris (RPD) from the root canal walls, especially in necrotic teeth is important for successful endodontic outcome. The aim of this study was to evaluate the RPD removal efficacy of handpiece mounted continuous irrigation with simultaneous root canal preparation from the apical third of root canals as compared to conventional syringe irrigation (SI).

Materials and Methods  Ninety extracted teeth were randomly divided into three groups: SI; handpiece mounted continuous irrigation (CI); and both syringe and continuous irrigation (CI+SI). After root canal preparation, roots were sectioned at 1 (a), 3 (b) and 5 (c) mm from apex and prepared for Hematoxylin-Eosin staining. Sections were microscopically examined for presence of RPD.

Statistical Analysis  Intergroup difference in average percentage of RPD at different root levels was calculated by using analysis of variance test (ANOVA). Tuckey test was used for pairwise comparison.

Results  ANOVA showed significant difference between all three groups ( p < 0.05). SI group showed a significantly higher percentage of RPD as compared with CI and CI+ SI groups at all root levels ( p < 0.01). At root level a, CI showed a significantly higher percentage of RPD as compared with CI+SI ( p < 0.01).

Conclusion  Handpiece mounted CI during rotary instrumentation showed a significant reduction in RPD as compared with conventional syringe irrigation. This technique was found to be an effective method for an enhanced root canal debridement.

Mapping the periapex anatomical pattern of teeth involved in sodium hypochlorite accidents: a cross-sectional quasi-experimental study

AIM

To determine the anatomical reasons for sodium hypochlorite (NaOCl) accidents by testing whether this mishap is likely to occur in cases where the anatomical apex of the teeth fenestrates the overlying buccal cortical alveolar bone, allowing NaOCl to gain direct access to buccal soft tissues.

METHODOLOGY

Following a cross-sectional, nonrandomized design, 13 patients who suffered unintentional NaOCl accidents whilst undergoing root canal treatment were included. After remission of symptoms, the root canals were fully irrigated with an innocuous radiopaque solution (saline diluted Claritrast 300) and subsequently CBCT scanned to create a 3D-map of the periapex and tracking of the irrigant pathway throughout the periapical tissues. An extra group of five control patients, who underwent root canal treatment with no NaOCl accident, was also CBCT-scanned after irrigation with the tracking radiopaque solution. The anatomical relationship of the cortical bone and the root apex, as well as the distribution of irrigation solution in the periapical tissue, was associated with patients undergoing a NaOCl accident or not, using a Fisher's exact test.

RESULTS

The frequency of teeth with apical cortical fenestration was significantly higher in the NaOCl accident-positive group, compared to the negative (P < 0.001). All 13 accident-positive patients had an anatomical apex in direct contact with the buccal soft tissue via fenestration of the overlying cortical bone and direct contact of the foramen with the soft tissues. The radiopaque solution was distributed in the soft tissue in these cases. In contrast, accident-negative patients had no fenestration of the buccal cortical bone and the anatomical root apex was within the cancellous bone or within a bone-confined periapical lesion. The radiopaque solution was also found in the cancellous bone or the periapical lesion, but patients had no manifestations of a NaOCl accident.

CONCLUSION

This quasi-experimental cross-sectional clinical study suggests that, in addition to the presence of the extruded NaOCl solution, a patent foramen that fenestrates the cortical bone merging into the mucosal tissue might constitute a risk for the clinical manifestation of a NaOCl accident. Preoperative 3D scans aid in anticipating when an accident is likely to occur.

Investigation of an Improved Side-Vented Needle and Corresponding Irrigation Strategy for Root Canal Therapy with CFD Method

BACKGROUND AND OBJECTIVE

This research aimed to present an improved side-vented needle and explore its availability as well as the corresponding irrigation strategy.

METHODS

A CFD model was used to simulate the irrigant flow in a simplified prepared round root canal with an apical delta respectively with different needles for irrigation. The needle types include flat end-tip needle, original side-vented needle, and improved side-vented needle. Different insertion depths and inlet velocities were contrastively studied, as well as the gap size between the bulb at the end tip of the improved side-vented needle and the root canal. The study includes a total of 13 schemes. Velocity, pressure, and shear stress in the root canal were measured to contrast the internal flow-field details and irrigation efficiencies between different schemes.

RESULTS

Poor irrigation replacement appeared in the schemes without enough needle insertion no matter which kind of needle has been used, though relatively lower pressure emerged at the apical foramen. On the contrary, deepening needle insertion not only brings better irrigant replacement but also higher apical foramen pressure. The original side-vented needle tends to make lower pressure at the apical foramen and simultaneously worse irrigant replacement as compared to the flat end-tip needle. The fluid entering the apical anatomy part deceases a lot as the original side-vented needle was replaced by the improved one. The scheme using the improved side-vented needle with gap size ratio and inlet velocity respectively equaling 5.0% and 5.50m/s can be considered the best one.

CONCLUSIONS

The improved side-vented needle can ensure acceptable irrigant replacement performance without leading to a high-pressure level at the apical foramen. The gap between the bulb and the wall of the root canal is very crucial for the pressure at the apical. The ideal irrigation strategy is ensuring the gap equals zero. However, it is a little hard to realize during the whole procedure of the root canal preparation except the final step. Consequently, another strategy that keeping the value of gap size ratio as small as possible such as less than 15% and simultaneously ensuring lower-velocity coming fluid, is necessary in the non-final irrigation.

Effect of different irrigation methods in the presence of a separated instrument: an in vitro study

Objective: The aim of this study was to evaluate the effect of different irrigation methods on sodium hypochlorite (NaOCl)/debris extrusion and dentinal tubule penetration of 2.5% NaOCl in the presence of an apically separated instrument.Materials and methods: Sixty root canals of freshly extracted mandibular single-rooted premolars were chemomechanically prepared up to ProTaper F2. Manual needle irrigation (30-gauge/side-vented) with 2.5% NaOCl was performed between files and a smear layer was removed with 17% ethylenediaminetetraacetic acid. Three mm of notched ProTaper F3 files were separated in the apical third of the roots. Samples were then randomly divided according to the final irrigation systems as follows: EndoActivator, EndoVac, manual needle irrigation, passive ultrasonic activation, and RinsEndo. Samples were mounted to Eppendorf tubes and root canals were irrigated with 3-mL Rhodamine B-labelled 2.5% NaOCl, which was applied using one of the above-mentioned methods. The extruded NaOCl/debris weight was calculated by extracting pre-irrigation weights of tubes from post-irrigation ones. Samples embedded in acrylic resin were sectioned transversely in 1-mm thicknesses at apical 1- and 3-mm levels. NaOCl's penetration depth and percentage into the dentinal tubules were evaluated with the aid of a confocal laser scanning microscope. Data were analysed statistically with Kruskal-Wallis and post hoc Siegel-Castellan tests (p < .05).Results: EndoVac significantly decreased the extruded NaOCl/debris compared to RinsEndo, passive ultrasonic activation, and EndoActivator in the presence of a separated instrument (p < .05). The penetrability of NaOCl significantly increased with the use of RinsEndo and EndoVac compared to the remaining groups (p < .05).Conclusion: In the presence of an irretrievable separated instrument, it could be suggested that devices with apical negative pressure such as EndoVac may improve the penetrability of irrigation solutions to the apical part of the root while preserving periapical tissues from NaOCl/debris extrusion.

The influence of the addition of surfactants to sodium hypochlorite on the removal of hard tissue debris

AIM

To evaluate the effect of the addition of surfactants to sodium hypochlorite (NaOCl) on the removal of accumulated hard tissue debris (AHTD), before and after final irrigation with 17% EDTA, from mesial canals of mandibular molars through microcomputed tomographic (micro-CT) analysis.

METHODOLOGY

Thirty moderately curved mandibular mesial roots with Vertucci type II canal configuration were selected and scanned in a micro-CT device at an isotropic resolution of 22.9 μm. The specimens were assigned to three groups (n = 10) with respect to the root length, degree of curvature of the mesial root, volume and 3D anatomy of the root canals according to the irrigating solution used during root canal preparation: 2.5% NaOCl and 0.1% Benzalkonium Chloride, 2.5% NaOCl and 0.1% Tween 80 and 2.5% NaOCl without additives. The root canals were instrumented up to Reciproc R25 instrument. Then, the specimens were scanned again after canal preparation and after final irrigation with 17% EDTA, and the registered data sets were examined to evaluate the percentage of AHTD. For comparison between the different groups before and after using 17% EDTA, the Kruskal-Wallis test was used with a significance level of 5%. For comparison between the same groups before and after using 17% EDTA, the Wilcoxon test was used with a significance level of 5%.

RESULTS

None of the irrigant solutions tested was able to completely eliminate hard tissue debris from mesial canals of mandibular molars. There were no significant differences in the percentage of AHTD amongst the different irrigation solutions (P > 0.05). Final irrigation with 17% EDTA significantly reduced the percentage of AHTD (P < 0.05), without differences amongst the groups (P > 0.05).

CONCLUSIONS

The addition of surfactants to NaOCl did not affect the removal of AHTD from mesial canals of extracted mandibular molars. Final irrigation with 17% EDTA significantly improved AHTD removal.

Effect of Pulse Energy, Pulse Frequency, and Tip Diameter on Intracanal Vaporized Bubble Kinetics and Apical Pressure During Laser-Activated Irrigation Using Er:YAG Laser

Objective: Er:YAG laser-activated irrigation (LAI) is an effective method of root canal cleaning, but irrigant extrusion from the apical foramen has been a concern. We aimed to analyze the effects of pulse energy, pulse frequency, and laser tip diameter on intracanal vapor bubble kinetics and periapical pressure generation during LAI with Er:YAG laser. Background: Irrigant vapor bubble kinetics are one of indices of root canal cleaning efficacy. However, few studies have compared laser pulse conditions to vapor bubble kinetics, in relation to periapical pressure. Methods: A plastic root canal model (apical diameter 0.50 mm, 6% taper, 20 mm long) was filled with distilled water, and LAI with Er:YAG laser (Erwin AdvErl Unit; 30, 50, or 70 mJ; 10, or 20 pulses per second; laser tip R200T or R600T) was performed with the end of the tip fixed at 15 mm from the root apex. The number, maximum diameter, and velocity of vapor bubbles were analyzed by high-speed video imaging. Pressure generated outside the apical foramen was measured with a pressure sensor. Results: Vapor bubble count and maximum diameter increased significantly with pulse energy, pulse frequency, and tip diameter. Vapor bubble velocity increased significantly with pulse frequency, but not with pulse energy or tip diameter. Periapical pressure increased significantly with pulse energy, pulse frequency, and tip diameter. Conclusions: The pulse frequency was the single factor that significantly affected all the examined parameters (the number, diameter, and velocity) of vapor bubble kinetics together with the periapical pressure.

Root canal obturation materials and filling techniques for primary teeth: In vitro evaluation in polymer-based prototyped incisors

BACKGROUND

Achieving a void-free root canal filling is a challenge in current clinical pulpectomy practice.

AIM

To compare filling effectiveness and internal voids of root filling materials and obturation techniques in resin-prototyped primary incisors by micro-CT.

DESIGN

Fifty prototypes were instrumented and randomly divided (n = 10) according to the filling materials (Vitapex^® , ZOE, Calcicur^® , Feapex, and Calen^® -ZO) and obturation technique: lentulo or pressure syringe (n = 5). The specimens were micro-CT scanned (pixel size = 7.83 μm) and reconstructed, and the total volume of filled canal (%FC) and internal voids (%IV) of the bulk filling material was calculated. Kruskal-Wallis and Mann-Whitney tests were used to detect differences and interactions among groups.

RESULTS

Calen^® -ZO, Vitapex^® , and ZOE showed similar %FC. Calcicur^® showed lower %FC compared with Calen^® -ZO, Vitapex^® , and ZOE (P < .05) but similar to Feapex. No statistically significant differences in %FC between lentulo or pressure syringe were disclosed. Regarding %IV, Vitapex^® , and Calen^® -ZO performed better with syringe, although Calcicur^® was better with lentulo. The number of voids in the obturation bulk was similar among materials, but always lower (P < .05) in syringe filled specimens.

CONCLUSION

Vitapex^® , Calen^® -ZO, and ZOE outperformed Calcicur^® and Feapex in %FC and if the syringe technique is used, %IV of the obturation bulk and presence of defects was lower.

Relationship between canal morphology and isthmus in mesio-buccal roots of maxillary first molars in 9- to 12-year-old children: An in-vivo cone-beam computed tomography analysis

OBJECTIVES

This study aims to analysis the distribution of root canal isthmuses (RCIs), and its relationship with canal morphology in the mesio-buccal roots of maxillary first molars in children aged 9-12 in a Chinese sub-population.

METHODS

494 healthy, untreated maxillary first molars with fully developed mesio-buccal roots were examined. Cone-beam computed tomography (CBCT) scans were acquired as part of diagnosis and treatment plannings unrelated to the present study. The images were evaluated to identify the canal morphology of mesio-buccal roots according to Vertucci's classification. A map-reading strategy was used to identify RCIs.

RESULTS

In mesio-buccal roots, the most common canal morphology was type Ⅳ (38.5 %). The frequency of type I (1.6 %) was much lower than adults. RCIs were found in 92.5 % mesio-buccal roots. The RCIs which began in the cervical third and ended in the middle third (CT-MT) (31.0 %) had the highest frequency. In type III, the RCIs which began and ended in the middle third (MT-MT) (30.3 %) were most common. For type V, 30.8 % RCIs began in the cervical third and ended in the apical third (CT-AT). No significant differences were found between sexes and sides (P > 0.05).

CONCLUSIONS

For children aged 9-12, the frequency of type I canals was much lower in mesio-buccal roots of maxillary permanent first molars, while the frequency of RCIs was higher than adults, especially in the apical third. The distribution of RCIs had its own characteristics in each canal type, closely related to the structures.

Micro-CT evaluation of sonically and ultrasonically activated irrigation on the removal of hard-tissue debris from isthmus-containing mesial root canal systems of mandibular molars

AIM

To evaluate the efficacy of sonically and ultrasonically activated irrigation on removal of accumulated hard-tissue debris (AHTD) in mesial root canal systems of mandibular molars using micro-computed tomographic (micro-CT) analysis.

METHODOLOGY

Forty mesial roots of mandibular molars with two independent canals joined apically by an isthmus (Vertucci type II) were selected. The root canals were instrumented using Reciproc R25 instruments, and specimens were scanned at a resolution of 10.5 μm. Subsequently, n = 10 roots were assigned to each of the four final irrigation groups such that the group means and variances were almost identical: sonically activated irrigation with EndoActivator (EA) or EDDY (ED), ultrasonically activated irrigation (UAI) and manual irrigation without activation (MI). The final irrigation procedures were performed using a total of 5 mL 1% NaOCl and 5 mL 15% EDTA per canal over 5 min with activation time of 4 × 20 s. Reconstructed data sets were coregistered, and the mean percentage reduction of AHTD after final irrigation was compared statistically between groups using analysis of variance at a significance level set at 5%.

RESULTS

A significant reduction of AHTD was achieved after final irrigation in all groups (P < 0.05), ranging from 44.1% to 66.8%. The vol% of debris after irrigation was 3.7 ± 1.9% for EA, 3.3 ± 2.3% for ED, 2.1 ± 1.6% for UAI and 4.4 ± 2.3% for MI, with no significant difference between groups (P > 0.05).

CONCLUSIONS

None of the final irrigation protocols completely removed AHTD from mesial root canal systems in extracted human mandibular molars. Sonically and ultrasonically activated irrigation performed no better compared to manual irrigation.

Micro-CT comparison of XP-endo Finisher and passive ultrasonic irrigation as final irrigation protocols on the removal of accumulated hard-tissue debris from oval shaped-canals

OBJECTIVE

To compare the effectiveness of the XP-endo Finisher instrument and passive ultrasonic irrigation (PUI) as final irrigation protocols on the removal of accumulated hard-tissue debris (AHTD) from oval-shaped canals using micro-computed tomographic (micro-CT) analysis.

METHODS

Twenty mandibular incisors were anatomically pair-matched based on similar morphological dimensions (length, volume, aspect ratio, and configuration) through micro-CT analysis, prepared with Reciproc R25 instrument, scanned again, and assigned to one of the two experimental groups (n = 10), according to the final irrigation protocol: XP-endo Finisher and PUI. After the final irrigation protocols, the specimens were rescanned and the registered datasets were examined to quantify the amount of AHTD. Data were statistically analyzed using Student's t test with a significance level of 5%.

RESULTS

The final irrigation protocols were highly similar in terms of volumetric percentage reduction of AHTD (P = 1.000).

CONCLUSIONS

XP-endo Finisher and PUI showed the same effectiveness on the removal of AHTD. None of the tested final irrigation protocols completely removed the AHTD from oval-shaped root canals.

CLINICAL RELEVANCE

AHTD may be considered clinically relevant because it could harbor bacterial contents away from the disinfection procedures. Both final irrigation protocols were effective on the removal of AHTD.

Influence of size and insertion depth of irrigation needle on debris extrusion and sealer penetration

Objectives

To determine the effect of size and insertion depth of irrigation needle on the amount of apical extruded debris and the amount of penetration depth of sealer using a confocal laser scanning microscope (CLSM).

Materials and Methods

Twenty maxillary premolars were assigned to 2 groups (n = 10), according to the size of needle tip, 28 G or 30 G. Buccal roots of samples were irrigated with respective needle type inserted 1 mm short of the working length (WL), while palatal roots were irrigated with respective needle type inserted 3 mm short of the WL. Prepared teeth were removed from the pre-weighed Eppendorf tubes. Canals were filled with F3 gutta-percha cone and rhodamine B dye-labeled AH 26 sealer. Teeth were transversally sectioned at 1 and 3 mm levels from the apex and observed under a CLSM. Eppendorf tubes were incubated to evaporate the irrigant and were weighed again. The difference between pre- and post-weights was calculated, and statistical evaluation was performed.

Results

Inserting needles closer to the apex and using needles with wider diameters were associated with significantly more debris extrusion (p < 0.05). The position of needles and level of sections had statistically significant effects on sealer penetration depth (p < 0.05 for both).

Conclusions

Following preparation, inserting narrower needles compatible with the final apical diameter of the prepared root canal at 3 mm short of WL during final irrigation might prevent debris extrusion and improve sealer penetration in the apical third.

Efficacy of irrigant activation techniques in removing intracanal smear layer and debris from mature permanent teeth: a systematic review and meta-analysis

AIMS

To establish whether irrigant activation techniques (IATs) result in greater intracanal smear layer and debris removal than conventional needle irrigation (CNI).

METHODOLOGY

Six electronic databases were searched to identify scanning electron microscopy studies evaluating smear layer and/or debris removal following the use of manual dynamic activation (MDA), passive ultrasonic irrigation (PUI), sonic irrigation (SI) or apical negative pressure (ANP) IATs in mature permanent teeth. Meta-analyses were performed for each canal segment (coronal, middle, apical and apical 1 mm) in addition to subgroup analyses for individual IATs with respect to CNI. Outcomes were presented as standardized mean differences (SMD) alongside 95% confidence intervals (95% CI) and chi-squared analysis.

RESULTS

From 252 citations, 16 studies were identified. The meta-analyses demonstrated significant improvements in coronal (SMD: 1.15, 95% CI: 0.72-1.57 / SMD: 0.54, 95% CI: 0.29-0.80), middle (SMD: 1.30, 95% CI: 0.59-2.53 / SMD: 0.8, 95% CI: 0.58-1.13) and apical thirds (SMD: 1.22, 95% CI: 0.83-1.62 / SMD: 1.86, 95% CI: 0.76-2.96) for smear layer and debris removal, respectively. In the apical 1 mm IATs improved cleanliness; however, differences were insignificant (SMD: 1.15, 95% CI: -0.47-2.77). Chi-squared analysis revealed heterogeneity scores of 79.3-92.8% and 0.0-93.5% for smear layer and debris removal, respectively.

CONCLUSIONS

IATs improve intracanal cleanliness across a substantial portion of the canal, and therefore, their use is recommended throughout root canal preparation. However, current data is too heterogeneous to compare and identify superiority of an individual technique highlighting the need to standardize experimental protocols and develop a more representative research model to investigate the in vivo impact of IATs on clinical outcomes and periapical healing following root canal treatment.

Electro-Acupuncture is Beneficial for Knee Osteoarthritis: The Evidence from Meta-Analysis of Randomized Controlled Trials

Knee osteoarthritis (KOA) is a common chronic degenerative disease of the elderly. Electro-acupuncture (EA) is considered as a beneficial treatment for KOA, but the conclusion is controversial. This systematic review compiled the evidence from 11 randomized controlled trials to objectively assess the effectiveness and safety of EA for KOA. Eight databases including PubMed, Cochrane Library, Clinic trials, Foreign Medical Literature Retrial Service (FMRS), Science Direct, China National Knowledge Infrastructure (CNKI), Chinese Scientific Journal Database (VIP), and Wanfang Data were extensively searched up to 5 July 2016. The outcomes included the evaluation of effectiveness, pain and physical function. Risk of bias was evaluated according to the Cochrane risk of bias tool. Eleven RCTs with 695 participants were included. Meta-analysis indicated that EA was more effective than pharmacological treatment (RR [Formula: see text] 1.14; 95% CI [Formula: see text] 1.01,1.28; [Formula: see text]) and manual acupuncture (RR [Formula: see text] 1.12; 95% CI [Formula: see text] 1.02,1.22; [Formula: see text]). Also, EA had a more significant effect in reducing the pain intensity (SMD [Formula: see text]; 95% CI [Formula: see text]; [Formula: see text]) and improving the physical function in the perspective of WOMAC (MD [Formula: see text]; 95% CI [Formula: see text], 5.56; [Formula: see text]) and LKSS (pharmacological treatment: MD [Formula: see text]; 95% CI [Formula: see text], 6.64; [Formula: see text]). Furthermore, these studies implied that EA should be performed for at least 4 weeks. Conclusively, the results indicate that EA is a great opportunity to remarkably alleviate the pain and improve the physical function of KOA patients with a low risk of adverse reaction. Therefore, more high quality RCTs with rigorous methods of design, measurement and evaluation are needed to confirm the long-term effects of EA for KOA.