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Aim: The current research set out to examine and contrast the amounts of apically extruded debris produced by two distinct rotary files and hand files used in pulpectomy procedures. Materials and Methods: Forty‑five extracted primary mandibular molars were randomly divided into three groups for instrumentation. Prime Pedo™ files are in Group 1, DXL‑Pro Pedo files are in Group 2, and H and K files are in Group 3. Debris that had been apically extruded and collected in preweighed Eppendorf tubes was incubated for five days at 70°C. The weight of the Eppendorf tubes before and after instrumentation was subtracted to get the weight of the debris that was gathered. Results: It was noted that all three groups had significantly different amounts of material ejected from the tip. The groups with the lightest amounts of extruded debris were 1, 2, and 3, in that order. The most debris was extruded from the apex in Group 3. Conclusion: This suggests that rotary files are preferable to hand files because they reduce debris extrusion, which in turn reduces postoperative events following pulpectomy procedures. [ABSTRACT FROM AUTHOR]

Irreversible pulpitis and pulp necrosis resulting from severe carious lesions or dental trauma, represent the most frequent clinical diagnoses in the indication of pulpectomies. In the realization of this therapy, pediatric rotary systems are gaining more and more acceptance due to the benefits they provide compared to the classic manual files. The present study has dual purpose: to present to the international scientific community the Endo Kids rotary system and to evaluate its effectiveness in the mechanical instrumentation of temporary teeth, based on the presentation of clinical cases and opinions of users on the advantages and disadvantages of this pediatric file system. According to the results obtained, it is concluded that the rotary file system Endo Kids provides effectiveness for mechanical instrumentation in temporary teeth, even in young children, because thanks to its design characteristics and ease of use, they allow pulpectomies to be performed in a single session and without complications. [ABSTRACT FROM AUTHOR]

Aim: To assess the canal transportation and centering ability in the mandibular first molars' curved mesiobuccal canals after instrumentation with file systems XP endo Shaper, self-adjusting File (SAF), Hyflex EDM, Pro Taper NEXT, WaveOne Gold, and K files with the help of Cone-Beam Computed Tomography (CBCT). Materials and Methods: Ninety recently extracted mandibular first molars with mesiobuccal roots that had a 25-30 degree canal curvature were assessed. Following preoperative CBCT scans, teeth were allocated randomly to six experimental groups of fifteen. After preparation with XP endo Shaper, SAF, Hyflex EDM, Pro Taper Next, WaveOne Gold, and K files, post-instrumentation scans were taken using same parameters as pre operative scans. At 3 mm, 6 mm, and 9 mm from the apex, samples were assessed for canal transportation and centering ratio. Results: Apical transportation was least for XP endo Shaper as compared to other groups except SAF and the results were statistically significant. K file showed the highest apical transportation toward the lateral wall of the root canal. XP endo Shaper was better in maintaining centering ability of middle and apical third of canal and SAF was better in maintaining centering ability of coronal third. Conclusion: In root canal preparation, least apical transportation and better centering ability with XP endo Shaper than other file systems compared. K file showed the highest transportation. [ABSTRACT FROM AUTHOR]

Introduction: Multiple systems are available for chemo-mechanical preparation during pulpectomy, but an evolution of the exclusive paediatric rotary single file system has opened new doors in paediatric endodontics. The aim was primarily to compare the quality of obturation and instrumentation time and secondarily to report pain perception between manual files and rotary file systems in deciduous molars. Materials and Methods: Pulpectomy was performed in 60 carious mandibular primary molars indicated for pulpectomy in children aged 4-8 years after considering the selection criteria. These teeth were divided randomly into three groups of 20 each, wherein canals were prepared using Hand K files in Group 1, HeroShaper Rotary File System in Group 2 and Kedo S Square single paediatric rotary file in Group 3. The quality of obturation was assessed using intraoral radiographs, and instrumentation time was recorded in seconds using a stopwatch. Pain during instrumentation was assessed using Wong Baker's FACES Pain Scale. Collected data were subjected to analysis using the Chi-square test, one-way ANOVA and Honestly Significant Difference post hoc test. Results: Mean instrumentation time was least for the Kedo-S Square file system (57.47 ± 9.26), followed by the HeroShaper group (99.6 ± 23.62), and maximum time was recorded for Hand files (255.99 ± 46.20), and this difference was statistically significant (P = 0.00), whereas there was no significant difference regarding the quality of obturation and pain perception between the three groups. Conclusion: As the Kedo S Square system showed the fastest canal preparation, it can be recommended for pulpectomy procedures in primary teeth because the length of appointment is directly proportional to the behaviour of the child. [ABSTRACT FROM AUTHOR]

Background: Using hand files in primary teeth is time-consuming, can lead to the formation of unwanted curvatures, and can cause iatrogenic errors. To overcome these difficulties, rotary instrumentation using nickel-titanium files was done. Aims: The present study was conducted to clinically evaluate and assess the difference in manual versus rotary instrumentation in root canals of primary teeth concerning instrumentation duration, obturation duration, quality of fills, and complications encountered. Also, the success of pulpectomy using hand files versus rotary files was assessed. Materials and Methods: 40 primary mandibular molars were randomly allocated to two groups namely control group subjects (n=20) that were treated using manual instrumentation and intervention group (n=20) using rotary instrumentation. The success was established in absence of excessive tooth mobility, sinus tract presence, gingival abscess/swelling, tenderness on percussion, and/or pain history. The collected data were subjected to statistical evaluation for results formulation. Results: The mean time for instrumentation was 25.69±3.82 minutes for the manual instrumentation group, whereas, for the rotary group it was significantly lesser (19.35±4.92) with p<0.0001. Mean obturation time for the manual group was 5.21±0.89 minutes and was lesser for the rotary group with 4.71±0.97 minutes (p=0.09). At 3 and 6 months, 97.36% (n=37) cases were considered successful in the manual instrumentation group, whereas 92.10% (n=35) cases in the rotary group were successful. At 18 months, 91.66% (n=33) pulpectomies were considered clinically successful in the manual group and 86.11% (n=31) cases in the rotary group were successful clinically. Conclusion: The present study concludes that less instrumentation time is needed with rotary instruments than manual instruments. Obturation quality and clinical success were similar in both manual and rotary instrumentation. [ABSTRACT FROM AUTHOR]

The aim of the present systematic review was to perform a qualitative synthesis of in vitro studies that assess the cyclic fatigue resistance of rotary glide path (GP) files of endodontic applications. Systematic electronic searches were performed in the Medline, Embase, Scopus, SciELO, and Web of Science databases on 15 February 2022, and were last updated on 1 April In vitro studies that evaluated and compared the cyclic fatigue resistance of at least one rotary GP file system with another rotary GP file system were included. A total of 25 studies were included in the qualitative synthesis. All studies assessing the difference in the cyclic fatigue resistance between continuous and reciprocating rotation in rotary glide path files found that the latter resulted in a significantly higher cyclic fatigue resistance, as evidenced by a higher number of cycles until fracture and/or time until fracture. Within the limitations of this review and the in vitro nature of the included studies, the results indicate that the cyclic fatigue resistance of rotary GP files may be influenced by several intrinsic factors of the files, such as their taper, cross-sectional design, alloy properties, kinematics, and external factors, such as the curvature and radius at which the file is activated, the irrigation or lubricant used, and the temperature. [ABSTRACT FROM AUTHOR]

Aim: To assess postoperative pain and bacterial reduction following the use of XP‐endo Shaper versus conventional rotary files in preparation of oval canals with necrotic pulps. Methodology: This superiority, parallel, randomized, double blinded clinical trial was conducted in the clinic of the Endodontic Department, Faculty of Dentistry, Cairo University, Egypt. Sixty single‐canalled mandibular premolars with necrotic pulps were randomly assigned into two equal groups. Canals were instrumented using XP‐endo Shaper files in the intervention group and iRaCe rotary files in the control group. Bacterial samples were taken before and after canal instrumentation. Incidence and severity of postoperative pain was assessed using a modified VAS after 6, 12, 24 h and daily for 5 days. A culture method was used to assess the number of bacterial colony forming units. Incidence of analgesic intake as well as flare‐ups was recorded. Data were analysed using chi‐square, Fisher Exact, Mann–Whitney, Independent t‐test, and Spearman's correlation for pain and bacterial counts. Results: The XP‐endo Shaper compared with the iRaCe group was associated with a significantly lower incidence of postoperative pain at 6, 12, and 24 h (P = 0.039, 0.047, and 0.026, respectively), and severity of postoperative pain at 6 h (mean difference: 1.33, 95% CI: 0.307–2.352, P = 0.02), 12 h (mean difference: 1.1, 95% CI: 0.26–1.936, P = 0.007), 24 h (mean difference: 0.94, 95% CI: 0.178–1.701, P = 0.008) and 48 h (mean difference: 0.97, 95% CI: 0.192–1.747, P = 0.038). There was a significant decrease in bacterial count following canal instrumentation in both groups (P < 0.001) with no significant difference between them (mean difference: 0.83 × 105, 95% CI: 0.336 × 105–1.996 × 105, P = 0.56). A weak correlation existed between postoperative pain severity and bacterial counts (P = 0.54). There was no significant difference in analgesic intake between the two groups (P = 0.085). Flare‐ups occurred in 3.3% of teeth in the iRaCe group, while no flare‐ups occurred in the XP‐endo Shaper group. Conclusions: XP‐endo Shaper was associated with a significantly lower frequency of postoperative pain for up to 24 h, and lower severity of postoperative pain for up to 48 h compared with iRaCe files. Both systems were equally effective in bacterial reduction from oval root canals with necrotic pulps. [ABSTRACT FROM AUTHOR]

Introduction: Apart from manual activation methods of irrigants during final irrigation procedure, multiple irrigant activation devices have been introduced which can influence the postoperative pain. Aim: To evaluate postoperative pain after final irrigation with open and closed-ended endodontic needles and Endoactivator during root canal treatment. Materials and Methods: This randomised controlled trial was conducted in Department of Conservative Dentistry and Endodontics, Bapuji Dental College and Hospital, Davangere, from June 2018 to August 2018. Total of 75 symptomatic irreversible pulpitis patients were randomly assigned into three groups. In group EN-1, final irrigation protocol was performed with 30-gauge notched tip needle (Pac-Dent, India), group EN-2 using side-vented, closed 30-gauge needle (Max-i-Probe, Dentsply, USA) and in group EA using Endoactivator (Dentsply, USA). Pain using Visual Analog Scale (VAS) was evaluated at 8, 24 and 48 hours. Participants were prescribed Non-steroidal Anti-Inflammatory Drugs (NSAIDs) as an escape medication. Comparison between the three groups at each time interval was done using Kruskal Wallis test followed by Mann-Whitney U test as post-hoc test. Change in VAS score over different time intervals (8, 24 and 48 hours) in each group was compared using Kruskal Wallis test and Mann-Whitney U test. The p-value less than 0.05 was considered statistically significant. SPSS version 20 was used for statistical analysis. Results: Mann-Whitney U test revealed significant difference between EN-1 and EN-2 (p=0.002) and between EN-1 and EA (p<0.001) at 8-hour time interval; between EN-1 and EA (p=0.002) at 24 hour time interval and between EN-1 and EN-2 (p=0.01) as well as between EN-1 and EA (p=0.002) at 48 hour time. Mann- Whitney U test showed significant difference (p<0.05) in number of NSAIDs taken at 8 hour between EN-1 and EA (p=0.04) and between EN-2 and EA (p=0.01); at 8-24 hour between EN-1 and EA and between EN-1 and EN-2 (p<0.001); at 24-48 hour between EN-1 and EA and between EN-1 and EN-2 (p<0.001). Conclusion: Number of NSAIDS taken by patients was significantly higher in open-ended needle irrigation group compared to side-vented needle and Endoactivator group in all the three time intervals along with postoperative pain. Thus, during final irrigant activation, application of Endoactivator or side-vented needle can be more beneficial in decreasing the incidence of postendodontic pain. [ABSTRACT FROM AUTHOR]

Introduction: Geometrical designs of nickel-titanium (NiTi) rotary instruments have a considerable influence on their mechanical performance, and thereby have the tendency to fracture. Aim: To evaluate the effect of cross-sectional geometry, pitch, taper, and off-center cross-section on the stress distribution in NiTi instruments under bending and torsion conditions using finite element analysis (FEA). Materials and methods: Eleven theoretical three-dimensional finite element (FE) models of rotary instruments were constructed and divided according to the geometric design tested into; group 1 (cross-section geometry): four FE models with four different cross-section designs (triangle, convex triangular, parallelogram, and rectangle). Group 2 (pitch): three FE models with different pitches (5, 10, and 15 threads). Group 3 (taper): two FEA models with two different tapers (0.04 and 0.06). Group 4 (centering): two FEA models (off-centered and centered cross section). The behavior of the instrument under bending and torsional conditions was analyzed mathematically in SolidWorks software package. Results: The pattern of stress distribution was varied by altering cross-sectional geometry, pitch, taper, and off-center cross section. Conclusion: No single geometrical design could be beneficial for all stress conditions. To decrease the stress accumulation during bending of rotary files in curved root canals, the rotary NiTi instruments should be designed with rectangle cross-section configuration, low pitch, reduced taper, and with centered cross section. This design improved the flexibility of rotary NiTi instruments. However, to improve the torsional resistance during root canal preparation of narrow canals, the file should be designed with parallelogram cross-sectional configuration, low pitch, increased taper, and eccentric cross-section design. [ABSTRACT FROM AUTHOR]

Pulpectomy is the choice of treatment to preserve the necrotic primary teeth in the dental arch until exfoliation. The primary step in pulpectomy is the biomechanical preparation of root canals using different instrumentation techniques. The aim of this study was to evaluate the quality of obturation and instrumentation time using Kedo-S Square rotary file, conventional H and K files in primary molars. This randomized controlled trial involved 45 primary molars that are equally distributed for instrumentation with Kedo-S Square rotary file, conventional H and K files. Instrumentation time was recorded in seconds and postoperative radiographs were taken to assess the quality of obturation. Statistically significant difference was noted in the instrumentation time between the three groups, with least instrumentation time in Kedo-S Square file group (73.4 s). Also significant difference was observed in the quality of obturation between the groups, with higher optimal fill in Kedo-S Square file group (67%). Based on the findings of this study, the rotary system provided better quality of obturation with a higher number of optimal obturation and reduced instrumentation time as compared to manual instrumentation. [ABSTRACT FROM AUTHOR]

The objective of our study was to compare and assess the outcome of root canal preparation of maxillary molars with two nickel-titanium (NiTi) rotary systems using CBCT. Ten maxillary molars were selected for this study, randomly divided into 2 groups with respect to the angle of canal curvature and submitted to standardized radiographs and CBCT, before and after instrumentation with ProTaper Next (group 1) and One Shape (group 2). The canals were three-dimensionally reconstructed and evaluated for the following parameters: changes in canal volume, percentage of shaped canal walls and degree of canal transportation. Friedman One way ANOVA at 2mm, 5m and 8mm was used for the statistical analysis. There was no significant difference between the two groups before or after instrumentation. Both rotary systems were efficient and safe in shaping the root canals, without deviation of the original pathway of the canals. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To examine the cyclic fatigue resistances of R‐Pilot, HyFlex EDM and PathFile NiTi glide path files in S‐shaped artificial canals. Methodology: Twenty R‐Pilot (12.5/.04), 20 HyFlex EDM (10/.05) and 20 PathFile (19/.02) single‐file glide path files were included. Sixty files (n: 20/each) were subjected to static cyclic fatigue testing using double‐curved canals until fracture occurred (TF). The number of cycles to fracture (NCF) was calculated by multiplying the rpm value by the TF. The length of the fractured fragment (FL) was determined by a digital microcaliper. Six samples of fractured files (n: 2/each) were examined by SEM to determine the fracture mode. The NCF and the FL data were analysed using one‐way anova, post hoc Tamhane and Kruskal–Wallis tests using SPPS 21 software. The significance level was set at 5%. Results: In the double‐curved canal, all the files fractured first in the apical curvature and then in the coronal curvature. The NCF values revealed that the R‐Pilot had the greatest cyclic fatigue resistance, followed by the HyFlex EDM and PathFile in both the apical and coronal curvatures (P < 0.05). Conclusions: R‐Pilot NiTi glide path files, used in a reciprocating motion, had the greatest cyclic fatigue resistance amongst the tested NiTi glide path files in an artificial S‐shaped canal. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study is to determine the potential for microcracks in the radicular dentin of first maxillary premolars using three different mechanized endodontic instrumentation systems. Methods: Eighty extracted maxillary first premolars with two root canals and no externally visible microcracks were selected. Root canal instrumentation was performed with either the ProTaper file system, the WaveOne primary file, or the self-adjusting file (SAF). Teeth with intact roots served as controls. The roots were cut into segments and examined with an intensive, small-diameter light source that was applied diagonally to the entire periphery of the root slice under ×20 magnification; the presence of microcracks and fractures was recorded. Pearson's chi-square method was used for statistical analysis, and significance was set at p < 0.05. Results: Microcracks were present in 30 and 20 % of roots treated with the ProTaper and WaveOne systems, respectively, while no microcracks were present in the roots treated with the SAF ( p = 0.008 and p = 0.035, respectively). Intact teeth presented with cracks in 5 % of the roots. The intensive, small-diameter light source revealed microcracks that could not be detected when using the microscope's light alone. Conclusions: Within the limitations of this study, it could be concluded that mechanized root canal instrumentation with the ProTaper and WaveOne systems in maxillary first premolars causes microcracks in the radicular dentin, while the use of the SAF file causes no such microcracks. Clinical relevance: Rotary and reciprocating files with large tapers may cause microcracks in the radicular dentin of maxillary first premolars. Less aggressive methods should be considered for these teeth. [ABSTRACT FROM AUTHOR]

Aim To evaluate the amount of apically extruded debris produced by ProTaper Universal ( PTU), ProTaper Next ( PTN), WaveOne ( WO) and Reciproc (R) systems after large apical preparations. Methodology Sixty mandibular premolars with a single canal were selected and randomly assigned into 4 groups ( n = 15) according to the system used for root canal preparation: PTU, PTN, WO and R groups. Canal preparations were performed up to size 40 in each group. Distilled water was used as an irrigant, and the apically extruded debris from each tooth was collected in pre-weighted glass vials and dried. The average weight of debris was assessed using a microbalance, and the data were analysed statistically using one-way analysis of variance and the post hoc Tukey multiple comparison test (α = 0.05). Results The PTU system was associated with significantly more debris than the other systems ( P < 0.05). No significant differences were found between PTN, WO and R systems ( P > 0.05). Conclusions All systems were associated with apical debris extrusion when canals were prepared to a large apical size. The PTU system was associated with more debris extrusion. [ABSTRACT FROM AUTHOR]

This systematic review and meta-analysis investigated the influence of the number of files (full-sequence rotary-file versus reciprocating single-file systems) used during root canal preparation on the apical extrusion of debris and its biological relationship with the occurrence of symptomatic apical periodontitis. An extensive literature research was carried out in the Medline, ISI Web of Science and Cochrane databases, for relevant articles with the keyword search strategy. Based on inclusion and exclusion criteria, two reviewers independently rated the quality of each study determining the level of evidence of the articles selected. The primary outcome for the meta-analysis was determined by the amount of debris extruded into the periapical tissue during root canal preparation with multiple- or single-file systems in four laboratory studies. Analysis of in vivo release of neuropeptides ( SP and CGRP) after root canal preparation with single- or multiple-file systems was also carried out. Amongst the 128 articles initially found, 113 were excluded for being nonrelevant or not fulfilling the selection criteria. Another four articles were excluded after methodology evaluation. Finally, nine laboratory studies and two in vivo studies were included in the systematic review. Four of the laboratory studies were further included for meta-analysis that revealed greater debris extrusion after the use of single-file techniques when compared to multiple-file systems. Analysis of in vivo neuropeptide expression in the periodontal ligament suggests that the design of the instrument is more important than the number of files used. Both rotary and reciprocating single-file systems generate apical extrusion of debris in laboratory studies, or expression of neuropeptides in vivo. Available evidence is limited, but supports the fact that this inflammatory reaction is not influenced by the number of files but the type of movement and the instrument design. [ABSTRACT FROM AUTHOR]

Aim To test and compare the effectiveness and safety of two size 20, .04 taper rotary files that were used to create a glide path for the self-adjusting file (SAF) in curved canals of mandibular molars. Methodology Forty mandibular molars with curved mesial roots and narrow MB root canals were selected based on a passage of size 15 K-files to WL; size 20 K-files could not reach WL. Only roots with no visible microcracks were included. Two types of size 20 rotary files were used for glide path preparation, the new Pre-SAF size 20, .04 taper file and the ProFile size 20, .04 taper, which served as the reference and control. Both files were used with 3-4 pecking strokes, which brought them to WL. Two parameters were tested whether the glide path allowed manual insertion of a 1.5-mm SAF file to WL and whether the procedure caused microcracks in the root dentine. Paired t-tests were used to compare the groups. Results Glide path preparation with both files allowed the manual insertion of the SAF file to WL in all 20 root canals, with no difference between the two groups. No cracks were detected after the procedure in any of the roots in either group. Conclusions Both types of size 20, .04 taper rotary files were effective for glide path preparation for the SAF file in curved canals. Neither file type caused microcracks in root dentine. [ABSTRACT FROM AUTHOR]

Aim To evaluate the failure mechanism of ProTaper Ni-Ti rotary instruments fractured under clinical conditions. Methodology A total of 46 ProTaper instruments that failed (fractured and/or plastically deformed) during the clinical use were collected from various dental clinics, whereas a new set of ProTaper instruments served as control. After inspection under stereomicroscopy the instruments were classified into three categories: (i) plastically deformed but not fractured, (ii) fractured with plastic deformation and (iii) fractured without plastic deformation. Three instruments from each group were analysed with computerized X-ray microtomography (micro-XCT) to detect surface and internal defects, whilst all the fracture surfaces were investigated under SEM. Results Stereomicroscopic inspection showed that 17.4% of the discarded instruments were only plastically deformed, 8.7% were fractured with plastic deformation and 73.9% were fractured without plastic deformation. Micro-XCT revealed instruments without any surface or bulk defects along with a few files with crack development below the fracture surface. No defects were identified in the unused instruments. SEM examination of fractured surfaces demonstrated the presence of dimples and cones, a typical pattern of dimple rupture developed because of ductile failure. Conclusions The results suggest that a single overloading event causing ductile fracture of ProTaper instruments is the most common fracture mechanism encountered under the clinical conditions. [ABSTRACT FROM AUTHOR]

This study compared preparations of curved canals, using Profile, GT file and Hero 642 rotary files. A total of 30 mesiobuccal canals of extracted first and second mandibular molars were used in this study. The teeth were embedded in resin and a pre-operative radiograph was taken. The specimens were then randomly divided into three instrument groups. Pre- and post-instrumentation radiographic images were scanned and superimposed using thevisi cad/cam program. At nine horizontal sections at 1 mm increments from the apex, it calculated pre- and post-instrumentation cross sectional areas (mm2) and enlargements to the inner aspect and outer aspects (mm). A Kruskal–Wallis test found no statistical difference among the groups in terms of total areas removed by each instrument ( P > 0·05). It also found no significant difference in any group between the total of the inner and outer enlargements ( P > 0·05). However the GT file removed significantly more material from the outer side of the canal than the inside at sections 3–5, and the Hero removed significantly more material from the outer side at sections 7–9 ( P < 0·05). All instruments produced preparations that maintained original canal curvatures. [ABSTRACT FROM AUTHOR]

Abstract Aim The aim of the present study was to assess debris and smear layer remaining following canal preparation with GT rotary instruments. Methodology Sixteen freshly extracted single-rooted premolar teeth were instrumented with GT™ rotary instruments using a crown-down preparation technique. All specimens were flushed with 2 mL of 5% NaOCl between each rotary instrument. At the end of instrumentation the following final irrigation sequence was repeated two times: 2 mL of EDTA + Cetrimide for 1 min (Largal Ultra, Septodont, France) and 2 mL of 5% NaOCl for 5 min. A final flush with saline solution was made to halt any chemical activity. Two other uninstrumented teeth that were not irrigated served as controls. All teeth were split longitudinally and prepared for SEM evaluation. The presence of debris and smear layer was evaluated from photomicrographs at ×200 and ×1000 magnification taken in the apical, middle and coronal thirds of the canals. Blind evaluation was performed by two trained observers and scores were compiled separately. A five category scoring system for debris and smear layer was used. Values obtained were tabulated and statistical analysis was carried out using a parametric chi-squared test. Results Statistical analysis showed that there was no significant difference between the three regions of the root canals (P > 0.05) for debris. Comparison of the removal of the smear layer between the three regions showed that there was a statistically significant difference between all parts, especially between the coronal and apical thirds (P < 0.001). Overall, the coronal sections were cleaner than the middle and apical sections. The uninstrumented canals showed walls completely covered with tissue, confirming that specimen preparation alone did not remove tissue. Conclusions Under the conditions of the present study GT™ rotary instruments removed debris effectively, but left root canal walls covered with smear layer,... [ABSTRACT FROM AUTHOR]

AbstractAim To determine the general efficacy and shaping ability of Hero 642 nickel–titanium rotary instruments during the preparation of simulated canals. Part 1 of this two-part report describes the efficacy of the instruments in terms of three-dimensional canal form. Methodology A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by Hero 642 instruments using a crown-down preparation sequence. The efficacy of the instruments was assessed in terms of preparation time, instrument failure, canal blockages and loss of canal length. Intra-canal impressions were taken of the prepared canals in order to assess three-dimensional canal form. Results The mean time for canal preparation was 8.6 min and was influenced significantly (P < 0.05) by canal shape. Two instruments fractured and eight instruments deformed; significant differences were observed between canal shapes (P < 0.05). All of the canals remained patent. Fifteen canals (39.5%) maintained the correct working distance, 15 lost distance and eight canals gained length. Examination of intracanal impressions demonstrated that the majority of canals (79%) had apical stops; canal shape had a significant influence (P < 0.001) on the quality of apical stops. With one exception all canals had smooth canal walls and all of the canals showed good flow characteristics. Taper was poor in 30 canals (79%) and good in eight canals (21%). Conclusions Hero 642 rotary nickel–titanium instruments prepared simulated canals rapidly but with a three-dimensional form that lacked adequate taper. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the shaping ability of ProFile 0.04 taper rotary nickel-titanium instruments with ISO sized tips in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using the ‘crown down’ approach recommended by the manufacturer. Part 2 of this two-part report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and the overall post-operative shape. Out of 37 completed specimens 9 zips (24%) and one ledge (3%) were created, but no perforations or danger zones were found. There were significant differences (P < 0.01) between canal shapes for the incidence of zips and elbows but not for their distance from the end-point of preparation. At specific positions along the canal length there were significant differences between the canal types in terms of their mean total width; overall, at the end-point of preparation and along the curved portion of the canals those specimens with 40° curves were widest. This trend continued for the width of material removed from the outer aspect of the canal curves, whereas along the inner aspect of curves more material was removed in the 20° canals. Overall, transportation was towards the outer aspect of the curve at the end-point of preparation and along the curved portion of canals but more balanced along the straight coronal section. Absolute transportation was small and below 0.1 mm at every position including the zips. Under the conditions of this study, ProFile nickel-titanium rotary instruments with ISO sized tips produced a larger number of zips than expected; however, the degree of zipping was limited and relatively minor. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the shaping ability of Quantec Series 2000 nickel-titanium instruments in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by Quantec instruments using the technique recommended by the manufacturer. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, change in canal length and three-dimensional canal form. The time necessary for canal preparation was on average 5.7 min and was significantly influenced (P < 0.01) by canal shape. One instrument fractured and three size nine instruments deformed; however, canal shape did not influence significantly instrument failure. All of the canals remained patent, none became blocked with debris. The majority of the canals maintained working distance (26 out of 40), however the mean change in length differed significantly (P < 0.05) between canal types. Overall, canals with 40° curves lost length whilst those with 20° curves gained in length. Examination of intracanal impressions revealed that preparation with Quantec Series 2000 instruments produced canals with definite apical stops, smooth canal walls and good flow and taper. However, the quality of apical smoothness and flow was influenced significantly (P < 0.0001) by canal shape with specimens having 40° canals displaying less desirable qualities. Under the conditions of this study, Quantec Series 2000 rotary nickel-titanium instruments prepared simulated canals rapidly, safely and with good three-dimensional form. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the shaping ability of ProFile 0.04 taper rotary nickel-titanium instruments with ISO sized tips in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using the ‘crown down’ approach recommended by the manufacturer. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. The time necessary for canal preparation was on average 5.2 min and was not influenced significantly by canal shape. Three instrument fractures occurred and a further 3 instruments deformed; size 35 instruments failed the most (4) followed by size 30 (2), four of the failures occurred in canals with 40° curves. None of the canals became blocked with debris and change in working distance was minimal. Intra-canal impressions of canal form demonstrated that most canals had apical stops and smooth canal walls whereas all canals had good flow and taper. Under the conditions of this study, ProFile 0.04 taper rotary nickel-titanium instruments with ISO sized tips prepared simulated canals rapidly and created good three-dimensional form. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the shaping ability of ProFile.04 Taper Series 29 nickel-titanium instruments in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using a step-down approach. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. The time necessary for canal preparation was not influenced significantly by canal shape. No instrument fractures occurred but a total of 52 instruments deformed. Size 6 instruments deformed the most followed by sizes 5, 3 and 4. Canal shape did not influence significantly instrument deformation. None of the canals became blocked with debris, and loss of working distance was on average 0.5 mm or less. Intra-canal impressions of canal form demonstrated that most canals had definite apical stops, smooth canal walls and good flow and taper. Under the conditions of this study, ProFile.04 Taper Series 29 rotary nickel-titanium instruments prepared simulated canals rapidly and created good three-dimensional form. A substantial number of instruments deformed but it was not possible to determine whether this phenomenon occurred because of the nature of the experimental model or through an inherent design weakness in the instruments. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the shaping ability of ProFile.04 Taper Series 29 rotary nickel-titanium instruments in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using a step-down approach. Part 2 of this two-part report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and the overall postoperative shape. No zips, perforations or danger zones were created although 24 specimens (60%) had ledges on the outer wall of the canal. The incidence of ledges differed significantly (P < 0.001) between the canal shapes. At specific points along the canal length there were highly significant differences (P < 0.001) in total canal width and in the amount of material removed from the inner and outer aspects of the curve between the various canal shapes. Overall, 40° canals were wider than 20° canals and canals with curves which began 8 mm from the orifice were wider than 12 mm canals. The direction of canal transportation at the end-point of preparation was balanced between inner and outer in the 8 mm canals, but more often towards the outer in the 12 mm canals. At the apex of the curve, transportation was invariably towards the outer aspect of the curvature. At the beginning of the curve, transportation was more balanced between inner and outer. Mean absolute transportation, ignoring direction, was generally greater in 40° canals and in those with the curve beginning 8 mm from the orifice. Of particular importance was the finding that excessive resin was removed from the outer aspect of the canal at the apex of the curve which was often associated with irregular widened areas or ledges. This is in contrast to the pattern of tissue removal found with stainless steel hand instruments where more resin is removed from the inner aspect of the canal at the apex, to create a danger zone. [ABSTRACT FROM AUTHOR]

Background: Flexibility during bending is a critical feature that influences the performance and safety of endodontic nickel-titanium rotary instruments. Flexibility of the endodontic files could be assessed via laboratory test or indicated theoretically by finite element analysis (FEA). The aim of the study is to determine the cantilever load required for bending five different nickel-titanium (NiTi) rotary instruments (laboratory test) and to calculate maximum von Mises stresses due to bending moment and vertical displacement (deflection) (theoretically by FEA) and compare both results. Results: TF Adaptive file demonstrates the least cantilever load required for bending, the least von Mises stresses generated and the highest deflection of the endodontic files. Contrary, One Shape file reported the highest cantilever load required for bending, the highest von Mises stresses generated and the least deflection among all the tested endodontic files. Conclusion: The finite element analysis validated the results of the laboratory cantilever bending test for the examined nickel-titanium rotary instruments. [ABSTRACT FROM AUTHOR]

Abstract Bergmans L, Van Cleynenbreugel J, Beullens M, Wevers M, Van Meerbeek B, Lambrechts P. Progressive versus constant tapered shaft design using NiTi rotary instruments. International Endodontic Journal , 36 , 288–295, 2003. Aim To evaluate the influence of a progressive versus constant tapered shaft design on canal preparation by NiTi rotary techniques. Methodology A XMCT-scanner and custom-made software were used to nondestructively analyse the mesial canals of 10 extracted mandibular molars in 3D with a spatial resolution of 12.5 µm. Specimens (n = 10 per group) were scanned before and after preparation using ProTaper (progressive tapered) or K3 (constant tapered) files. Numerical values for volume, curvature, dentine removal and centring ratio were obtained in addition to a visual inspection for canal aberrations. Data were analysed by (multiway factorial) anova, Wilcoxon tests and t -tests. Results The volume of total dentine removal (mean ± SD) was 1.21 ± 0.66 mm3 (ProTaper) and 1.06 ± 0.23 mm3 (K3) (P > 0.05), and the amount of dentine removal at all separate horizontal regions examined was comparable for both groups. The mean linear dentine removal (transportation) was in the range of 8–212 µm (ProTaper) and 4–187 µm (K3). The resultant centring ratio varied from 0.01 to 0.24 (ProTaper) and from 0.01 to 0.17 (K3), whilst different straightening patterns were observed. A centre displacement towards the furcation coronally was most pronounced for the ProTaper group whereas a centre displacement towards the outer side of the curvature more apically was only observed for the K3 group. No severe canal aberrations were found. Conclusions The progressive tapered shaft design of the ProTaper instrument was less influenced by the mid-root curvature than the constant tapered design of the K3 instrument thereby providing a good centred apical preparation. However, ProTaper instruments tended to transport towards the furcation in the coronal region. [ABSTRACT FROM AUTHOR]

Abstract Mesgouez C, Rilliard F, Matossian L, Nassiri K, Mandel E. Influence of operator experience on canal preparation time when using the rotary Ni-Ti ProFile system in simulated curved canals. International Endodontic Journal , 36 , 161–165, 2003. Aim The aim of this study was to determine the influence of operator experience on the time needed for canal preparation when using a rotary nickel-titanium (Ni-Ti) system. Method A total of 100 simulated curved canals in resin blocks were used. Four operators prepared a total of 25 canals each. The operators included practitioners with prior experience of the preparation technique, and practitioners with no experience. The working length for each instrument was precisely predetermined. All canals were instrumented with rotary Ni-Ti ProFile Variable Taper Series 29 engine-driven instruments using a high-torque handpiece (Maillefer, Ballaigues, Switzerland). The time taken to prepare each canal was recorded. Significant differences between the operators were analysed using the Student's t -test and the Kruskall–Wallis and Dunn nonparametric tests. Results Comparison of canal preparation times demonstrated a statistically significant difference between the four operators (P < 0.001). In the inexperienced group, a significant linear regression between canal number and preparation time occurred. Conclusion Time required for canal preparation was inversely related to operator experience. [ABSTRACT FROM AUTHOR]

Abstract Bergmans L, Van Cleynenbreugel J, Beullens M, Wevers M, Van Meerbeek B, Lambrechts P. Smooth flexible versus active tapered shaft design using NiTi rotary instruments. International Endodontic Journal , 35 , 820–828, 2002. Aim The aim of this study was to evaluate the influence of a smooth flexible versus active tapered shaft design on canal preparation by NiTi rotary techniques. Methodology A XMCT-scanner (SkyScan 1072) and developed software (Bergmans et al . 2001) were used to nondestructively analyze the mesial canals of 10 extracted mandibular molars in 3D with a spatial resolution of 30 µm. Specimens (n = 10 per group) were scanned before (PRE) and after (POST) preparation using Lightspeed (smooth flexible) or GT-rotary (active tapered) files. Numerical values for volumes, dentine removal (net) transportation and centring ability were obtained in addition to a visual inspection on canal aberrations. Data were analyzed by Shapiro Wilk test, multiway factorial anova, Tukey–Kramer test, Wilcoxon test and t -test. Results Results indicated that the active tapered shaft removed significantly more dentine in the middle to apical portion of the root compared to the smooth flexible design. Both groups demonstrated some straightening, but no significant differences were found with respect to instrument types. However, absolute values for net transportation and centring ratio were small and no canal aberrations could be found. Conclusions The smooth flexible shaft design did not improve the morphological characteristics of canal preparation by NiTi rotary instruments when compared with the active tapered design. Therefore, system selection should be based upon other criteria. [ABSTRACT FROM AUTHOR]

Mandel E, Adib-Yazdi M, Benhamou L-M, Lachkar T, Mesgouez C, Sobel M. Rotary Ni-Ti profile systems for preparing curved canals in resin blocks: influence of operator on instrument breakage. International Endodontic Journal, 32, 436–443 1999. Aim The aim of this study was to determine the incidence of fracture of ProFile 0.4 and 0.6 taper Series 29 nickel-titanium instruments with respect to operator experience. Methodology A total of 125 simulated root canals in resin blocks with the same geometrical shape in terms of angle and radius of curvature and coronal and apical orifice diameter were used. Five operators prepared all the specimens using an identical step-down instrument sequence, each one preparing 25 canals. The operators included two endodontists and three general practitioners. Statistical data concerning the incidence of instrument failure was compiled using Statlab and Fisher’s partial least square difference analysis of variance. Results A total of 21 (16.8%) instruments fractured, all had 0.04 tapers. Nine size 25 instruments failed, 9 xsize 20 instruments failed and 3 size 15. During the study, the Binary Tree analysis of instrument failure revealed two operator populations belonging to two different study periods. The first period, which represented the first 13 root canal preparations, was called the ‘learning period’, and the second period, which represented the next 12 sample preparations, was called the ‘application period’. A greater number of instruments failed during the first period than during the second. In the ‘learning period’, both groups of operators learned the same way. In the ‘application period’, two groups could be distinguished; the first group consisted of a general practitioner who produced worse results, and the second group consisted of the other four operators. Conclusions The results indicate the necessity of mastering this rotary canal preparation... [ABSTRACT FROM AUTHOR]