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This study investigated variation in working length during multiple‐visit endodontic treatment. Patients (N = 106) with pulpitis or pulp necrosis, with or without apical periodontitis, were included. During the first appointment, glide path was performed with ProGlider and shaping with ProTaper Next. Working length was detected four times. Working length was then re‐recorded prior to filling during the second appointment and a 0.5 mm threshold was selected as the minimum clinically meaningful variation. A logistic regression model was used to evaluate the impact of tooth anatomy, preoperative pulp status, apical periodontitis and lesions of endodontic origin on working length variation. Working length varied between first and second appointments in 34% of patients. The presence of apical periodontitis was the only variable significantly associated with variation in working length (p = 0.011). These data suggest that working length should be re‐checked prior to root canal filling to prevent procedural errors. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the shaping ability of a modified ProTaper Next technique (PTNm) with that of TruNatomy (TN) in lower molars mesial curved canals using micro-computed tomography (Micro-CT). Sixty mesial canals of first mandibular molars were randomly assigned between two groups (n = 30). After canal scouting with K-File #10, glide path and shaping were carried out with TN or PTNm systems. The PTNm sequence consists of ProGlider, followed by ProTaper Next X1 and apical finishing with NiTiFlex #25 up to working length (WL) to ensure adequate apical cleaning. Samples were scanned using micro-CT and pre- and post-shaping volumes were matched to analyse geometric parameters: the volume of removed dentin; the difference of canal surface; centroid shift, minimum and maximum root canal diameters; cross-sectional areas; the ratio of diameter ratios (RDR) and the ratio of cross-sectional areas (RA). Measurements were assessed 2 mm from the apex and in relation to the middle and coronal root canal thirds. Data were analysed using ANOVA (p < 0.05). No statistically significant differences were found between the groups for any parameter at each level of analysis, except for RA at the coronal level (p = 0.037). The PTNm system showed the tendency to enlarge more in the coronal portion with a lower centroid shift at apical level compared with TN sequence (p > 0.05). Both PTNm and TN sequences demonstrated similar maintenance of original anatomy during the shaping of lower molar mesial curved canals. [ABSTRACT FROM AUTHOR]

Featured Application: Thanks to the use of confocal laser scanning microscopy, it is proved that ciprofloxacin, metronidazole and clarithromycin (3-MIXC) mixed with hyaluronic acid (HA) is a possible alternative to root canal disinfection during regenerative endodontic procedures (REPs) in order to avoid a substantial discoloration of the teeth, mainly due to the chelating effect of the minocycline. Confocal laser scanning microscopy (CLSM) was used to evaluate the antibacterial effect and depth of action of a novel clarithromycin-containing triple antibiotic mixture, which was proposed for root canal disinfection in dental pulp regeneration. A previous study reported that this mixture had no tooth discoloration effects in vitro. After infection with Enterococcus faecalis for 3 weeks, the dentinal tubules in the cylindrical root specimens were exposed to different antibiotic mixtures: ciprofloxacin, metronidazole and minocycline (3-MIX); ciprofloxacin, metronidazole and clarithromycin (3-MIXC) and ciprofloxacin and metronidazole (2-MIX). Each antibiotic formulation was mixed with macrogol (MG) or hyaluronic acid (HA) vehicles. CLSM and viability staining were used to quantitatively analyze the mean depth of the antibacterial effect and the proportions of dead and live bacteria inside the dentinal tubules. The 3-MIX and 3-MIXC demonstrated a similar depth of action. The mean proportion of dead bacteria was similar in the 3-MIX and 3-MIXC groups, and both were statistically higher than that of 2-MIX (p = 0.014). Each antibiotic mixture showed a higher bactericidal efficacy if conveyed with HA, compared to MG (3-MIX, p = 0.019; 3-MIXC, p = 0.013 and 2-MIX, p = 0.0125). The depth of action and the antibacterial efficacy of 3-MIXC seemed comparable with 3-MIX. [ABSTRACT FROM AUTHOR]

Introduction Contracted endodontic cavities (CECs) have developed from the concept of minimally invasive dentistry and provide an alternative to traditional endodontic cavities (TECs). They have been designed in an effort to preserve the mechanical stability of teeth. The contracted cavity design preserves more of the dentin but may influence the geometric shaping parameters. The aim of this micro–computed tomographic study was to evaluate the influence of contracted endodontic cavities on the preservation of the original root canal anatomy after shaping with nickel-titanium rotary instruments. Methods Thirty extracted human mandibular molars with fully formed apices and independent mesial canals were randomly assigned to group 1 (TEC) and group 2 (CEC). Each group was shaped using ProGlider (Dentsply Maillefer, Ballaigues, Switzerland) and WaveOne Gold (Dentsply Maillefer). Irrigation was performed with 10% EDTA and 5% sodium hypochlorite. Samples were scanned before and after canal shaping to match canal volumes (SkyScan; Bruker microCT, Kontich, Belgium [100 kV, 100 μA, and 15-μm resolution]), and images were analyzed to evaluate canal volumes, surface areas, and centroid shift on cross sections at −1 mm and −3 mm from the apex. Results TECs showed a greater preservation of the original root canal anatomy with less apical transportation than CECs, possibly because of the absence of coronal interferences and, therefore, fewer pecking motions required to complete instrumentation. Conclusions Within the limitations of this study, TECs may lead to a better preservation of the original canal anatomy during shaping compared with CECs, particularly at the apical level. [ABSTRACT FROM AUTHOR]

Introduction The aim of this micro–computed tomography study was to describe the shaping properties of ProGlider/ProTaper Next (PG/PTN) and ScoutRace/BioRace (SR/BR) nickel-titanium rotary systems. Methods Thirty maxillary first permanent molars were selected. Mesiobuccal canals were randomly assigned ( n = 15) to PG/PTN or SR/BR groups. Irrigation was performed with 5% NaOCl and 10% EDTA. Specimens were scanned (voxel size, 9.1 μm) for matching volumes and surface areas and post-treatment analyses. Root canal centering ability, canal geometry enlargement, and thickness of dentinal wall at inner curvature were assessed at apical level and point of maximum curvature. Results were analyzed with 4 one-way analyses of variance. Results Canal centering ability was superior in PG/PTN ( P = .006 at apical level, P = .025 at point of maximum curvature). PG/PTN demonstrated a more conservative increase of canal areas ( P = .027 at apical level, P = .038 at point of maximum curvature). Centrifugal increase in canal diameters did not significantly differ between groups ( P = .65 at apical level, P = .61 at point of maximum curvature). Inner dentinal wall thickness was less reduced with PG/PTN compared with SR/BR, with no statistical differences ( P = .23 at point of maximum curvature, P = .89 at apical level). PG/PTN shaping taper ranged between 6% and 7%. Conclusions Neither system produced significant shaping errors in curved canals. PG/PTN system showed better preservation of canal anatomy. PTN offset section did not influence final preparation taper. [ABSTRACT FROM AUTHOR]

Introduction Instrument failure caused by excessive torsional stress can be controlled by creating a manual or mechanical glide path. The ProGlider single-file system (Dentsply Maillefer, Ballaigues, Switzerland) was recently introduced to perform a mechanical glide path. This study was designed to compare the effect of a glide path performed with PathFiles (Dentsply Maillefer) and ProGlider on torque, time, and pecking motion required for ProTaper Next X1 (Dentsply Maillefer) to reach the full working length in simulated root canals. Methods Forty Endo Training Blocks (Dentsply Maillefer) were used. Twenty were prepared with a mechanical glide path using PathFiles 1 and 2 (the PathFile group), and 20 were prepared with a mechanical glide path using a ProGlider single file (the ProGlider group). All samples were shaped with ProTaper Next X1 driven by an endodontic motor connected to a digital wattmeter. The required torque for root canal instrumentation was analyzed by evaluating the electrical power consumption of the endodontic engine. Electric power consumption (mW/h), elapsed time (seconds), and number of pecking motions required to reach the full working length with ProTaper Next X1 were calculated. Differences among groups were analyzed with the parametric Student t test for independent data ( P < .05). Results Elapsed time and electric power consumption were significantly different between groups ( P = .0001 for both). ProGlider appears to perform more efficiently than PathFiles in decreasing electric power consumption of ProTaper Next X1 to reach the full working length. Conclusions This study confirmed the ability of ProGlider to reduce stress in ProTaper Next X1 during shaping through a glide path and preliminary middle and coronal preflaring. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: This study compared the canal curvature and axis modification after instrumentation with WaveOne Primary reciprocating files (Dentsply Maillefer, Ballaigues, Switzerland) and nickel-titanium (NiTi) rotary ProTaper (Dentsply Maillefer). Methods: Thirty ISO 15, 0.02 taper, Endo Training Blocks (Dentsply Maillefer) were used. In all specimens, the glide path was achieved with PathFile 1, 2, and 3 (Dentsply Maillefer) at the working length (WL). Specimens were then assigned to 1 of 2 groups for shaping: specimens in group 1 were shaped with ProTaper S1-S2-F1-F2 at the WL and specimens in group 2 were shaped with WaveOne Primary reciprocating files at the WL. Pre- and postinstrumentation digital images were superimposed and processed with Matlab r2010b (The MathWorks Inc, Natick, MA) software to analyze the curvature-radius ratio (CRr) and the relative axis error (rAe), representing canal curvature modification. Data were analyzed with one-way balanced analyses of variance at 2 levels (P < .05). Results: The instrument factor was extremely significant for both the CRr parameter (F1 = 9.59, P = .004) and the rAe parameter (F1 = 13.55, P = .001). Conclusions: Canal modifications are reduced when the new WaveOne NiTi single-file system is used. [Copyright &y& Elsevier]

Abstract: Introduction: X-ray computed micro-tomography scanning allows high-resolution 3-dimensional imaging of small objects. In this study, micro-CT scanning was used to compare the ability of manual and mechanical glide path to maintain the original root canal anatomy. Methods: Eight extracted upper first permanent molars were scanned at the TOMOLAB station at ELETTRA Synchrotron Light Laboratory in Trieste, Italy, with a microfocus cone-beam geometry system. A total of 2,400 projections on 360° have been acquired at 100 kV and 80 μA, with a focal spot size of 8 μm. Buccal root canals of each specimen (n = 16) were randomly assigned to PathFile (P) or stainless-steel K-file (K) to perform glide path at the full working length. Specimens were then microscanned at the apical level (A) and at the point of the maximum curvature level (C) for post-treatment analyses. Curvatures of root canals were classified as moderate (≤35°) or severe (≥40°). The ratio of diameter ratios (RDRs) and the ratio of cross-sectional areas (RAs) were assessed. For each level of analysis (A and C), 2 balanced 2-way factorial analyses of variance (P < .05) were performed to evaluate the significance of the instrument factor and of canal curvature factor as well as the interactions of the factors both with RDRs and RAs. Results: Specimens in the K group had a mean curvature of 35.4° ± 11.5°; those in the P group had a curvature of 38° ± 9.9°. The instrument factor (P and K) was extremely significant (P < .001) for both the RDR and RA parameters, regardless of the point of analysis. Conclusions: Micro-CT scanning confirmed that NiTi rotary PathFile instruments preserve the original canal anatomy and cause less canal aberrations. [Copyright &y& Elsevier]

Abstract: Introduction: This study evaluated the influence of glide path on canal curvature and axis modification after instrumentation with WaveOne Primary reciprocating files. Methods: Thirty ISO 15, 0.02 taper Endo Training Blocks were used. In group 1, glide path was created with PathFile 1, 2, and 3 at working length, whereas in group 2, glide path was not performed. In both groups, canals were shaped with WaveOne Primary reciprocating files at working length. Preinstrumentation and postinstrumentation digital images were superimposed and processed with Matlab r2010b software to analyze the curvature radius ratio (CRr) and the relative axis error (rAe), representing canal curvature modification. Data were analyzed with 1-way balanced analyses of variance at 2 levels (P < .05). Results: Glide path was found to be extremely significant for both CRr parameter (F = 9.59; df = 1; P = .004) and rAe parameter (F = 13.55; df = 1; P = .001). Conclusions: Canal modifications seem to be significantly reduced when previous glide path is performed by using the new WaveOne nickel-titanium single-file system. [Copyright &y& Elsevier]

Abstract: Introduction: This study evaluated the working length (WL) modification after instrumentation with WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) reciprocating files and the incidence of overinstrumentation in relation to the initial WL. Methods: Thirty-two root canals of permanent teeth were used. The angles of curvature of the canals were calculated on digital radiographs. The initial WL with K-files was transferred to the matched WaveOne Primary reciprocating files. After glide paths were established with PathFile (Dentsply Maillefer, Ballaigues, Switzerland), canals were shaped with WaveOne Primary referring to the initial WL. The difference between the postinstrumentation canal length and the initial canal length was analyzed by using a fiberoptic inspection microscope. Data were analyzed with a balanced 2-way factorial analysis of variance (P < .05). Results: Referring to the initial WL, 24 of 32 WaveOne Primary files projected beyond the experimental apical foramen (minimum–maximum, 0.14–0.76 mm). A significant decrease in the canal length after instrumentation (95% confidence interval ranging from −0.34 mm to −0.26 mm) was detected. The canal curvature significantly influenced the WL variation (F1 = 30.65, P < .001). The interaction between the initial canal length and the canal curvature was statistically significant (F2 = 4.38, P = .014). Conclusions: Checking the WL before preparation of the apical third of the root canal is recommended when using the new WaveOne NiTi single-file system. [Copyright &y& Elsevier]

In endodontically treated teeth, cuspal coverage plays a fundamental role in reducing the risk of fracture. However, the adhesive techniques with or without fiber post increased the possibilities in restoring root-filled teeth. The aim of this study was to determine the effect of the fiber post and/or post length and/or cuspal coverage on the fracture resistance of endodontically treated maxillary premolars. Seventy intact single-rooted maxillary premolars were selected and divided in seven groups of ten each: 'intact teeth' (control), 'inlay without fiber post' (G1), 'inlay with long fiber post' (G2), 'inlay with short fiber post' (G3), 'onlay without fiber post' (G4), 'onlay with long fiber post' (G5), and 'onlay with short fiber post' (G6). Except for intact teeth, all specimens were prepared with a mesio-occluso-distal (MOD) cavity, endodontically treated and restored with or without long or short post, with or without cusp coverage. All specimens were thermal-cycled, exposed to a cyclic loading, and then submitted to the static fracture resistance test. Fracture loads and mode of failure were evaluated. A statistically significant difference in fracture resistance was found between group 1 and the other groups ( p < 0.001). χ2 test showed statistically significant differences in the patterns of fractures between the groups ( p < 0.001). The highest number of favorable fractures was observed in groups 3 and 4. Similar fracture resistance was detected in maxillary premolars endodontically treated with MOD cavity preparations, restored with either direct resin composite with fiber post or cusp capping. The 'short post' direct restoration may be a valid alternative in the restoration of root-filled premolars. [ABSTRACT FROM AUTHOR]

Abstract: The study compared changes to canal curvature and incidence of canal aberrations after preflaring with hand K-files or with nickel-titanium rotary PathFile in S-shape Endo Training Blocks. The influence of the operator''s expertise was also investigated. One hundred training blocks were colored with ink, and preinstrumentation images were acquired digitally. Preflaring was performed by an endodontist with PathFile (group 1) and hand stainless steel K-files #10-15-20 (group 2); an inexpert clinician performed preflaring with PathFile (group 3) and hand stainless steel K-files (group 4). Preinstrumentation and postinstrumentation images were superimposed to evaluate the outcomes investigated. Differences in canal curvature modification and incidence of canal aberration were analyzed with the Kruskall-Wallis plus post hoc tests and by the Monte Carlo method, respectively, (P < .05). The PathFile groups demonstrated significantly less modification of curvature (P < .001) and fewer canal aberrations (P < .001). No expertise-related difference was found within instrument groups (P > .05), whereas the inexpert clinician produced more conservative shaping with Pathfiles than did the expert with manual preflaring (P < .01). [Copyright &y& Elsevier]

This meta-analysis aimed to evaluate postoperative pain (POP) following root canal filling (RCF) with gutta-percha/bioceramic sealer (BCS) vs. gutta-percha/traditional sealer (TS) techniques. Electronic databases were searched for randomized trials. Subgroup analyses were performed for analgesic intake, flare-ups, postoperative time (24/48 h), pulp status, and retreatment. The search yielded 682 records, and nine studies were selected. BCS was associated with significantly lower POP vs. TS at 24 h (P = 0.04) and 48 h (P = 0.0005). In addition, non-significant trends favoring BCS for analgesic intake at 24 h (P = 0.14), flare-ups (P = 0.24) and obturation techniques at 24 h (P = 0.41) and 48 h (P = 0.33), non-significant trends for lower POP with TS vs. BCS 24 h and 48 h in vital teeth (P = 0.50, P = 0.18, respectively), and for lower POP with BCS vs. TS in non-vital teeth at 24 h and 48 h (P = 0.16, P = 0.84, respectively). POP was numerically lower with TS vs. BCS at 24 h (P = 0.65) and 48 h after retreatment (P = 0.59). Moreover, POP did not vary between fillers when the treatment was over single (P = 0.28) or multiple visits (P = 0.50). BCS was associated with significantly lower short-term POP, and with a trend for lower analgesic intake and flare-up incidence, as compared to TS. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to compare the effective shaping time and number of rotations required by an endodontist working with hand and rotary ProTaper instruments to completely shape simulated root canals. Eighty Endo Training Blocks (curved canal shape) were used. Manual preflaring was performed with K-Flexofiles #08-10-12-15-17 and #20 Nitiflex at a working length of 18 mm. Specimens were then randomly assigned to 2 different groups (n = 40); group 1 was shaped by using hand ProTaper and group 2 with ProTaper rotary. The number of rotations made in the canal and the effective time required to achieve complete canal shaping were recorded for each instrument. Differences between groups were analyzed with the nonparametric Mann-Whitney U test (P < .05). Hand ProTaper required significantly fewer rotations (P < .001) than rotary ProTaper, whereas the effective working time to fully shape the simulated canal was significantly higher (P < .001) with hand ProTaper. [Copyright &y& Elsevier]

Abstract: Introduction: The study evaluated the efficacy of subsonic agitation of sodium hypochlorite (NaOCl) in reducing bacterial load in the root canal. Methods: Root canals of 112 extracted human single-root teeth were preflared using K-Flexofiles (Dentsply Maillefer, Ballaigues, Switzerland) up to #20 and then shaped using ProTaper S1-S2-F1-F2-F3 (Dentsply Maillefer) at the working length. Irrigation was performed with 33 mL of 5% NaOCl, alternating with 10 mL of 10% EDTA. After ethylene oxide sterilization, the root canals were infected with 30 μL of Enterococcus faecalis culture and randomly assigned to four groups (n = 25) of different irrigation regimens plus positive and negative controls. Irrigation was performed with 2 mL of 5% NaOCl. In the NaOCl 15 group, the irrigant was left in place for 15 seconds, and in the NaOCl 30 group it was left in place for 30 seconds. In the EndoActivator (EA; Dentsply Tulsa Dental Specialties, Tulsa, OK) 15 and EA 30 groups, NaOCl was subsonically agitated with EA for 15 and 30 seconds, respectively. The residual bacterial count was then evaluated. Differences among groups were analyzed with one-way analysis of variance and the post hoc Bonferroni test (p < 0.05). Results: A statistically significant difference was evidenced among groups (F3 = 9.01, p < 0.001). The standard irrigation groups (NaOCl 15 and 30) showed higher microbial counts than the EA 30 group (p < 0.05). Conclusion: Thirty seconds of NaOCl subsonic agitation with EndoActivator appears to be slightly more effective in reducing bacterial load in the root canal compared with NaOCl irrigation alone. [Copyright &y& Elsevier]