Apical Third Of Canal Research Articles

Efficacy of Different Irrigant Activation Systems on Debris and Smear Layer Removal: A Scanning Electron Microscopy Evaluation.

Irrigation is an essential component of root canal treatment to enable cleaning beyond the reach of mechanical instruments. The study aimed to assess and compare the efficacy of different final irrigation protocols, including sonic- and ultrasonic-powered irrigant-activation systems, on debris and smear layer removal in the coronal, middle, and apical thirds of straight oval root canals. Straight oval root canals of 60 human mandibular incisors were prepared to size 40.04 and divided into four groups (n = 15) according to the final irrigation protocols: (a) Eddy sonic activation (b) endosonic passive ultrasonic irrigation (PUI), (c) irrisafe PUI, and (d) manual syringe and needle irrigation with no additional activation, which served as control. After the treatment procedures, the roots were split and observed using scanning electron microscopy. The presence of remaining debris and smear layer at the coronal, mid-root, and apical thirds of the canals were evaluated using a score system and statistically analyzed using multinominal models with significance level set at p < 0.05. None of the final irrigation protocols completely removed all debris and smear layer from all root canals. When the syringe and needle were used without activation, more debris and smear layer were found in the apical third of the canals. Activation of the final irrigant with each of the three devices significantly reduced the presence of debris in the apical third, compared to the syringe and needle final irrigation, with no difference among the three activation devices. Eddy and irrisafe activation also significantly reduced the residual smear layer in the apical third, compared to syringe and needle alone, while the reduction in the remaining smear layer by endosonic activation did not reach the significance level. Removal of debris and smear layer from the apical part of the root canal by syringe and needle irrigation alone may be significantly improved by using sonic or ultrasonic activation of the final irrigant. Endosonic activation was less effective in removal of smear layer from the apical part of the canals compared to the other two activation systems.

Comparative Evaluation of Root Canal Transportation and Centering Ability in Curved Mesiobuccal Canals of Mandibular First Molars after Instrumentation with Different File Systems-An In vitro Study.

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). 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. 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. 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.

The Impact of Different Final Apical Preparation Diameters on the Efficiency of Photon-Induced Photoacoustic Streaming (PIPS) in Removing the Smear Layer at the Apical Third

Aims: Photon-induced Photoacoustic streaming (PIPS) as an adjunct to conventional irrigation (CI) using different final apical preparation diameters on smear layer (SL) Material and method: Clinical crown was removed from forty human mandibular molars standardizing root length to 18 mm. Chamber was opened and straight-line access was established Working length was kept 1 mm short of the apex. Teeth were randomly divided into 4 investigated groups based on the final apical diameter. Group-1 (F1+CI+PIPS), Group-2 (F2+CI+PIPS), Group-3 (F3+CI+PIPS) and Group-4 (F3+CI) (Control). CI protocol (2.5% NaOCl+17% EDTA+2.5% NaOCl+distilled water). SEM magnification of 5000x dentinal tubules’ patency at the apical third of root canals was assessed. ANOVA and Tukey’s HSD test were used for data analysis (p = 0.05) Results: Group-3 (F3+CI+PIPS displayed the highest mean scores (3.64±0.50) of SL removal from the apical third of the canal. However, Group-1 (F1+CI+PIPS) exhibited the lowest mean scores (1.27±0.47). Intergroup comparison analysis revealed that Group 1 and Group 2 (F2+CI+PIPS) presented the lowest and most comparable SL removal (p &gt;0.05) Conclusion: Photon-induced Photoacoustic streaming should be considered as an adjunct therapy to improve the cleanliness of the Smear layer from the apical third.

Retrieval of File from Canal Apical Third: A Report of Two Cases

Background: Procedural mishaps can occur during any step of root canal during cleaning and shaping, and might affect the prognosis of treatment. Among these separation of instruments in the canal is one of the most troublesome incidents in endodontic therapy especially if the fragments cannot be removed. Several techniques have been employed to facilitate the removal of the fragments; however, they are technique sensitive, expensive and require great expertise. Aim: This paper aims to suggest combination of techniques for retrieval of file from apical or beyond the apical third of canal. Materials and Methods: A 30year old patient presented with pain in upper anterior tooth. Clinical examination revealed a temporary restoration in 21 with no soft tissue abnormality. A radio-visio-graph indicated 22 associated with periapical radiolucency and a separated file extending 3mm beyond the radiographic apex in the periapical area. Retrieval of the separated instrument was planned using braiding technique followed by obturation and post endo restoration. Second case report includes a female 43 years old with pain in upper lateral incisor. IOPA radiograph revealed a separated instrument in the apical third of root canal. Retreatment was planned by first bypassing the fractured file and then using ultrasonics to loosen the fragment followed by obturation and post endodontic restoration. Conclusion: Combining different techniques during file retrieval can retrieve file with minimal dentinal destruction. Keywords: braiding, bypass, file retrieval, H file, K file, instrument separation, ultrasonics.

Sealing Ability of Obturation with Different Sealers Applied Over Apically Separated Rotary File - Retrograde Bacterial Leakage Study.

Background and Aims. Retrieval of separated rotary file may not be possible many times. Then sealing of coronal root canal system depends on sealing ability of root canal sealers. The type of seal to be obtained should be bacterial-tight seal. Hence it is important to evaluate the sealing ability of obturation with different newer sealers with separated file in apical 3rd of root canals with bacterial penetration method using e.fecalis.Methods:Forty six human mandibular molars extracted for periodontal reasons were collected. After Decoronation of teeth Protaper rotary S1 files (Dentsply Maillefer) were intentionally separated in apical third of canal and obturated with gutta-percha (Prime Dental Products, India) along with zinc oxide eugenol sealer (Dental products of India-Mumbai) in Group I, Nano Zinc oxide eugenol (Nano Research Lab, Jharkand, India) in Group II and MTA sealer (Angelus, Londrina, Brazil) in Group III. Samples were assessed for bacterial leakage with E fecalis for 48 hours. The number of colony forming units was assessed.Results:The values obtained were subjected to one way ANOVA test and significance level was set to 0.05. Group I scored the highest mean value of (6.58), followed by Group II (3.91). The lowest Mean value was with Group III (2.91). However there was no statistical significant difference in Mean values among groups with (p-value 0.05).Conclusion:The mean value of colony forming units in Group III was 2.91, in Group II 3.91 and 6.58 in Group I. None of the groups demonstrated complete bacteria-tight seal.

Efficiency of XP endo Shaper (XPS) and irrigation protocol on the quality of cleaning the apical third of root canal: SEM study

Background/Aim: The aim of this study was to evaluate the efficacy of new rotary NiTi instrument XP-endo SHAPER (XPS) used with two irrigation protocols on the root canal cleaning in the apical area. Material and Methods: The research was conducted on 30 single-rooted teeth extracted for orthodontic reasons which were divided into the two groups. Instrumentation of the canals was conducted with XPS instrument and 2% solution of NaOCl was used as irrigant. Instrumentation in the first group was performed using a conventional continuous irrigation, in the second group, protocol of final irrigation was performed intermittently in 3 cycles. The SEM analysis of the apical third of the canal was performed on longitudinal root cross-section standardized photomicrography with a magnification of 2000X. Results: Results showed that a thicker smear layer was observed in the first group and with continuous irrigation protocol (2,10) in relation to the intermittent irrigation protocol in 3 cycles (1,96), but without significant differences. The walls of the root canal in the apical third of the samples of the second group were slightly cleaner (73.3%) in comparison with the teeth of the first group (64, 7%), but also without significant differences. Conclusions: The use of XPS and 2% solution of NaOCl in the root canal enables efficient cleaning of the apical third of tooth. The final irrigation protocol in three cycles improves the efficiency of the smear layer removal in the apical segment of the canal.

Comparison of 980 nm Diode Laser and Q-Mix Solution Alone and in Combination on Removal of Smear Layer from Root Canal Surface; a Scanning Electron Microscope Study

Aim: The aim of this study was to compare the efficacy of 980 nm diode laser and QMix 2in1 solution (DENTSPLY Tulsa Dental Specialties) alone and in combination, for smear layer removal from the root canals. Background: Smear layer is an amorphous layer formed on root canal walls following instrumentation. This layer should be removed as it can harbor bacteria and bacterial products and prevents the penetration of intracanal medicaments into the dentinal tubules. Irrigation agitation techniques have been proposed recently to remove smear layer from root canals more efficiently. The diode laser has the potential for irrigant activation and studies are needed to establish their efficacy for smear layer removal especially from apical thirds of canals. Methods: Forty extracted single-rooted permanent human teeth were used. Root canals were prepared to full working length using manual K-files (MANI) till 40K. Prepared teeth were divided into four groups (n=10): Group 1, no irrigation; Group 2, QMix 2in1 solution; Group 3, diode laser; Group 4, QMix 2in1 in combination with a diode laser. The roots were split longitudinally and prepared for scanning electron microscopic (SEM) investigation. The split roots were examined for remaining smear layer at the coronal, middle, and apical portion of each canal under a scanning electron microscope (JSM5910, JEOL, Japan) at 1000x magnification. Results: Smear layer removal was scored according to Guttman rating system for remaining smear layer scores (Gutmann et al.). Diode laser in combination with QMix solution had the least smear layer scores. Conclusions: Diode laser irradiation in combination with QMix 2in1 solution effectively removes smear layer from apical thirds of root canals.

Time-dependent effect of various irrigants for root canal on smear layer removal

Background:Existence of smear layer in root canals caused by instrumentation is believed to prevent penetration of irrigating agents, thereby resulting in endodontic treatment.Aims and Objectives:To compare and evaluate the effectiveness of two irrigants: 17% ethylenediaminetetraacetic acid (EDTA) and mixture of tetracycline isomer, an acid, and a detergent (MTAD) as final agents for eliminating the smear layer.Materials and Methods:We included 50 human lower premolar teeth whose crowns were sectioned at cementoenamel junction. The sample was randomly grouped into five groups, each with 10 teeth. Group 1: 1 mL of 17% EDTA as final rinse for 1 min, Group 2: 1 mL of 17% EDTA for 30 s, Group 3: 5 mL of MTAD for 2.5 min, Group 4: 5 mL of MTAD for 5 min, and Group 5: saline. The specimens were sectioned vertically all along the long axis and fixed on an aluminum stub for gold ion sputtering. Scanning electron microscope was used to observe the specimens, and photomicrographs were taken at coronal, middle, and apical thirds of canal, and assessed by Torabinejad scoring system by two examiners, and the observations were analyzed statistically.Results:When Group 1 and Group 2 and Groups 3 and 4 were compared, we found a significant variation in removal of smear layer at cervical and middle thirds, and insignificant difference at apical third. In comparison with EDTA and saline, MTAD was more efficient significantly in middle and cervical thirds and insignificant at apical third.Conclusion:MTAD is an efficient irrigant for removing smear layer than EDTA and saline.

Shaping ability of BioRace, ProTaper NEXT and Genius nickel-titanium instruments in curved canals of mandibular molars: a MicroCT study.

To evaluate and compare the canal shaping ability of BioRace, ProTaper NEXT and Genius engine-driven nickel-titanium (NiTi) file systems in extracted mandibular first molars using micro-computed tomography (MCT). Sixty mesial root canals of mandibular first molars were randomly divided into three equal groups, according to the instrument system used for root canal preparation (n=20): BioRace (BR), ProTaper NEXT (PTN) or Genius (GN). Root canals were prepared to the full WL using a crown-down technique up to size 35, .04 taper instruments for BR and GN groups and size 30, .07 taper instruments for the PTN group. MCT was used to scan the specimens before and after canal instrumentation. Changes in dentine volume, the percentage of uninstrumented canal surface and degree of canal transportation were evaluated in the coronal, middle and apical thirds of canals. Data were analysed statistically using one-way analysis of variance and Tuckey's post hoc tests with the significance level set at 5%. There were no significant differences between the three groups in the terms of dentine removed after preparation and determination of the root canal volume, or percentage of uninstrumented canal surface (P>0.05). No significant differences were found between the systems for canal transportation in any canal third (P>0.05). The shaping ability of the BR, PTN and GN NiTi file systems was equally effective. All instrumentation systems prepared curved root canal systems with no evidence of undesirable changes in 3D parameters or significant shaping errors.

Management of Separated Instruments in Apical Third of Extremely Curved Canals: A Case Report

This report describes the case of a 23 years old male patient who presented with the chief complaint of pain in mandibular right lower first molar tooth. Detailed clinical and radiographic examination revealed acute pulpitis in lower right second premolar and first molar teeth. During root canal instrumentation, a rotary instrument separated at the apical third of mesiobuccal canal. After careful assessment, it was decided to bypass the instrument and obturate the root canal space with warm vertical compaction using thermoplasticized gutta percha and resin based sealer materials. After considering the curvature of canal, thin root of tooth and location of broken instrument in the apical third of canal space, attempts of instrument removal were ruled out as a treatment option for the patient. Bypassing the broken instrument fragment with pre-curved hand files of small sizes was chosen as a predictable treatment option since it is not associated with removal of excessive remaining dentin from the roots of the teeth. Hence, teeth do not become weak and risk of post-operative root fracture is minimized. Due to successful bypassing and preparation of root canal space beyond broken instrument, canal was shaped, cleaned and disinfected adequately. Decision of instrument bypassing or removal should be taken with extreme care. Bypassing the instrument in apical third of root canal space with thin rooted teeth is the most conservative and practical approach, and objectives of adequate shaping and cleaning of canals can be achieved successfully without compromising remaining tooth structure.

The efficacy of XP-endo SHAPER (XPS) in cleaning the apical third of the root canal

Abstract Introduction The aim of this study was to evaluate the efficacy of new rotary NiTi instrument XP endo SHAPER (XPS) used with conventional irrigation protocol on the root canal cleaning in the apical area. Material and methods The research was conducted in vitro on 40 extracted single-rooted teeth divided into the four groups. Instrumentation in the first group was performed using iRa Ce NiTi rotary instruments, in the second group the same instruments were used plus XP endo FINISHER (XPF) for smear layer removal. In the third group, canal instrumentation was done using new instrument XPS, and in the fourth XPS instruments plus XPF was used. During the instrumentation 2% NaOCl solution was used for rinsing canals. The SEM analysis of the cleaning quality in the apical third of the canal was performed on longitudinal root cross-sections and standardized microphotography with a 2000x magnification. Results The thickest smear layer in the apical third was recorded in the first group (iRa Ce) NiTi instruments (2.12), and somewhat less in the group with the new XPS instrument (1.95). An identical and somewhat smaller amount of smear layer was registered in the second and fourth groups where XPF was used with the final irrigant (1.64) (p&lt;0.001). Conclusion The application of only one instrument (XPS) in the canal enabled efficient cleaning of a very complex apical third. Cleaning was more efficient when XPF was used with final irrigant after the canal instrumentation.

Fracture of nickel titanium rotary instrument during root canal treatment and re-treatment: a 5-year retrospective study.

To evaluate retrospectively the incidence of K3 nickel titanium rotary instrument fracture in referred cases during root canal treatment and re-treatment. Clinical and radiographic reports of 12867 endodontic cases treated at the King Abdulaziz medical city between January 2010 and November 2015 were reviewed to obtain information on intracanal fractured instruments with respect to the treatment performed, tooth type and the size and at what level the instrument fractured (coronal, middle or apical). The degree of canal curvature was classified into mild (<10° ), moderate (10-25° ) or severe (>25° ). Logistic regression was used to test the incidence of instrument fracture in relation to the root canal treatment performed and tooth type. Chi-square tests were used to analyse the fracture incidence in the treated teeth in respect to fracture level and fractured file diameter. The level of significance was set at 0.05. Root canal treatment was performed on 8946 cases, whilst re-treatment was performed on 3921 cases. The fracture incidence was higher during re-treatment cases (2.96%) than in primary root canal treatment (0.74%) (P<0.001) with a 1.41% incidence overall. There was a trend for more fractures in maxillary (1.68%) and mandibular (1.35%) molar teeth. Moreover, 56.6% of the fractured instruments occurred in severely curved canals, and the apical third of the root canal was the most common site for instrument fracture (85.7%), followed by middle (13.2%), and coronal (1.1%) thirds, mostly with file sizes 20 and 25 (59.9% and 25.27%, respectively). The fracture incidence of K3 instruments was significantly greater during root canal re-treatment than root canal treatment, mainly with small instruments and in the apical third of the canals.

A Comparative Evaluation of Smear Layer Removal Using Apical Negative Pressure (EndoVac), Sonic Irrigation (EndoActivator) and Er:YAG laser -An In vitro SEM Study.

BackgroundThis study aimed to compare the smear layer removing efficacy of the EndoActivator, EndoVac and Er:YAG laser in extracted mandibular premolars, at the apical, middle and coronal third of root canal, through scanning electron microscopy.Material and Methods40 extracted mandibular premolars were decoronated to a standardized length of 12 mm. Specimens were shaped to ProTaper F4 size and irrigated with 5.25% sodium hypochlorite at 370C between instrumentation. Teeth were divided into four groups (n=10), one control (needle irrigation) and three experimental, according to the irrigant activation technique used i.e. sonic irrigation (EndoActivator), apical negative pressure (EndoVac) or laser (Er:YAG). The final irrigants used were 10ml,17% ethylenediaminetetraacetic acid (EDTA) and 10ml, 5.25% sodium hypochlorite. Root canals were then split longitudinally and observed under a scanning electron microscope. The presence of smear layer at the apical, middle and coronal third of root canal was evaluated. Scores were analyzed by Kruskal-Wallis and Mann-Whitney U tests. Intraexaminer and interexaminer reliability were determined by Kappa test.ResultsThe EndoVac system was significantly more effective in removing debris from the apical third than all other groups. EndoActivator performed better than laser at the apical third. All three experimental groups (EndoVac, EndoActivator, and laser) were better than needle irrigation at the middle and apical third. At the coronal third, no significant difference was seen between the four groups.ConclusionsNone of the activation systems completely removes the smear layer from the dentine walls; nevertheless, EndoVac is significantly better in removing debris from the apical third of canal. Key words:EndoVac, EndoActivator, Er:YAG laser, smear layer, scanning electron microscopy.

A Micro–Computed Tomographic Assessment of the Influence of Operator's Experience on the Quality of WaveOne Instrumentation

IntroductionMicro–computed tomographic scanning was used to evaluate the influence of operator's experience on the time and quality of instrumentation of the mesial root canals of mandibular molars using WaveOne Primary files (Dentsply Maillefer, Ballaigues, Switzerland). MethodsThirty mandibular molars with 2 separate mesial canals were submitted to preoperative micro-CT scans. Teeth were randomly allocated to 3 groups: and experienced operator group and inexperienced groups before and after training with WaveOne files. Second scans were obtained after instrumentation. The volume of the untreated canal, the volume of dentin removed after preparation; the amount of the uninstrumented area; and transportation to the coronal, middle, and apical thirds of canals were measured. The preparation time was also recorded. ResultsInstrumentation of canals increased their volume and surface area in all groups. No significant differences between experienced and inexperienced (with and without training) groups in the apical, middle, and coronal sections were detected although coronal transportation was slightly larger in both inexperienced groups than in the experienced group. The inexperienced operator without training used significantly more time for instrumentation than the experienced operator (P < .05); after training for 1 month, the instrumentation time by the same inexperienced operator was reduced (P < .05) to close to the time of the experienced operator (P > .05). ConclusionsThe WaveOne instrumentation technique required a short learning curve for the inexperienced user in order to master this technology.

Scanning Electron Microscopic Evaluation of Root Canal Walls after shaping with Different Single-use Rotary Systems

ABSTRACT The aim of the present study was to investigate the cleaning efficacy of four new single-use rotary nickel–titanium (NiTi) systems. A total of 48 single-rooted freshly extracted teeth were divided into four groups. Root canals were shaped with the single-use NiTi systems (ProTaper Next, F360, OneShape and F6 SkyTaper) using 5.25% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) solutions. Specimens were fractured longitudinally and prepared for scanning electron microscopic (SEM) analysis at standard magnification of 2,500?. The presence/absence of debris smear layer and smear layer at coronal, middle, and apical third of each canal were evaluated using a five-step scale for scores. Numeric data were analyzed using Kruskal–Wallis and Mann–Whitney U statistical tests and significance was predetermined at p&lt; 0.05. Analysis of variance test showed no significant differences among the NiTi systems (p &gt; 0.05). The same results were assessed considering the smear layer scores. Analysis of variance confirmed that the apical third of the canal maintained a higher quantity of debris and smear layer after preparation of all the samples. All the single-use rotary NiTi systems left dentinal walls generally free of debris, even if a small amount of smear layer is visible, especially in the apical third of the root canal. All tested single-use systems seem to be effective in removing smear layer from root canals, if irrigating protocols are respected. How to cite this article Dagna A, Gastaldo G, Beltrami R, Bianchi S, Poggio C. Scanning Electron Microscopic Evaluation of Root Canal Walls after shaping with Different Single-use Rotary Systems. Int J Experiment Dent Sci 2016;5(2):93-98.

Comparison of Smear Layer Removal Using the Nd:YAG Laser, Ultrasound, ProTaper Universal System, and CanalBrush Methods: An In Vitro Study

IntroductionThe aim of this study was to compare the efficacy of the Nd:YAG laser, ultrasound, the ProTaper Universal system (Dentsply Maillefer, Ballaigues, Switzerland), and the CanalBrush (Coltene Whaledent, Langenau, Germany) methods for the removal of the smear layer from the apical third of root canals. MethodsFifty distal root canals from extracted human mandibular first molars were instrumented up to ProTaper Universal F5 and divided randomly into 5 groups (n = 10) according to the following final irrigation agitation techniques: no agitation (control), ProTaper Universal file, ultrasound, CanalBrush, and Nd:YAG laser. Specimens were observed under a scanning electron microscope. The presence of the smear layer was evaluated using a 3-grade scoring system. The data were analyzed with Cohen kappa, Kruskal-Wallis, and Mann-Whitney U tests. A level of significance of .05 was adopted. ResultsThe ultrasound group performed significantly better than the rest of the groups; 56.6% of the specimens revealed no smear layer, 44.4% showed the presence of a moderate smear layer, and no heavy smear layers were observed. In the Nd:YAG laser group, 30% of the specimens presented with no smear layer, 70% showed the presence of a moderate smear layer, and no heavy smear layers were observed. In contrast, a heavy smear layer was observed on the surfaces of the root canals in the CanalBrush (23.4%), ProTaper Universal (13.4%), and control (86.6%) groups. Statistically significant differences were observed (P < .05). ConclusionsNone of the agitation methods completely removed the smear layer. However, the ultrasound method performed significantly better followed by the Nd:YAG laser, the CanalBrush, and the ProTaper Universal system. Agitation of the irrigant improved smear layer removal in the apical third of the canal.

A Comparative SEM Investigation of Smear Layer Remaining on Dentinal Walls by Three Rotary NiTi Files with Different Cross Sectional Designs in Moderately Curved Canals

The objective of this study was to compare the smear layer formed on root canal walls during canal preparation of extracted human teeth by Twisted, Mtwo, and ProTaper rotary nickel titanium instruments. Sixty single rooted human premolar teeth with root curvature <25(0) were selected and randomly divided into three Groups (n= 20 teeth per Group). Three types of rotary nickel titanium instruments were used, Twisted (SybronEndo, Orange, CA, USA), Mtwo (VDW, Munich, Germany) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) according to manufacturer's instructions to instrument the root canals. Irrigation for all groups was performed after each instrument change with 3ml of 3% sodium hypochlorite followed by Glyde (File Prep, Dentsply, Maillefer, Ballaigues, Switzerland) as chelator paste and lubricant. Three different areas (coronal, middle and apical thirds) of the root canal were evaluated using scanning electron microscopy (SEM). The canal wall of each sample was assessed and compared using a predefined scale for the presence or absence of smear layer. Data were analysed statistically using ANOVA and Tukey HSD test Results: All three groups showed statistically significant more smear layer in the apical thirds of the canal as compared to the coronal and middle thirds (p<0.001). Mtwo rotary file system produced significantly less smear layer (p<0.001) compared to Twisted and ProTaper rotary instruments in the apical portion. Twisted Files resulted in less smear layer formation in the apical thirds of the canal compared to ProTaper rotary instruments but were statistically insignificant. Completely clean root canals were not found after instrumentation with any of the three instruments. Under the confines of this study Mtwo instruments produced significantly cleaner dentin wall surfaces throughout the canal length in comparison to Twisted and ProTaper rotary files. Twisted Files proved to be comparable to ProTaper rotary instruments with respect to canal cleanliness in the apical thirds of the root canal.

Root Canal Preparation of Mandibular Molars with 3 Nickel-Titanium Rotary Instruments: A Micro–Computed Tomographic Study

IntroductionThe aim of this study was to describe the canal shaping properties of ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Universal (PTU; Dentsply Tulsa Dental Specialties, Johnson City, TN), and WaveOne (Dentsply Maillefer) nickel-titanium instruments in mandibular first molars by using micro–computed tomographic (micro-CT) scanning. MethodsA total of 36 maxillary first molars with 2 separate mesial canals and 1 distal canal were selected and scanned preoperatively and postoperatively by using micro-CT scanning with a voxel size of 30 μm. Canals were prepared with PTU, PTN, and WaveOne systems under hypochlorite irrigation. The volume of the untreated canal; the volume of dentin removed after preparation; the amount of the uninstrumented area; and the transportation to the coronal, middle, and apical thirds of canals were measured. The preparation time and instrument failure were also recorded. ResultsInstrumentation of canals increased their volume and surface area. The distal canals had a significantly higher proportion of unprepared surfaces than mesial canals (P < .05). The PTN system produced less transportation than the WaveOne and PTU systems in the apical third of the mesial canals (P < .05). There was no significant difference on apical transportation in distal canals among the 3 instrument systems. Instrumentation with WaveOne was significantly faster than with the other 2 instruments (P < .05). ConclusionsThe PTN, PTU, and WaveOne instruments shaped root canals in mandibular first molars in vitro without significant shaping errors. The curved canals prepared using PTN had less apical transportation than the canals prepared using WaveOne and PTU.

두 가지 다른 행정의 니켈 티타늄 파일의 성형 성상: 표면 성상, 상아질 삭편과 도말층에 대한 예비적 비교 연구

Purpose: To assess the surface profile of dentinal wall, dentin chips and smear layer during the canal shaping with rotary (ProTaper) and ProFile and reciprocating (WaveOne) nickel-titanium file. Materials and Methods: Sixty human extracted mandibular premolars and incisors with single canals were randomly selected. Three experimental groups (n = 20) were instrumented with ProTaper (F2), ProFile (25/.06), WaveOne (25/.08) with irrigation of 2.5% NaOCl. The dentin chips were collected from flute of file during each canal preparation. After canal preparation, roots were grinded and each group was divided into two subgroups (n = 10) for surface profile and smear layer of dentinal wall of shaped root canal. Each specimen was observed under scanning electron microscope for evaluating size of dentin chips, root canal surface recessions and smear layer. Scores of Smear layer were statistically analyzed using Kruskal Wallis test and Mann Whitney test at P = 0.05 level. Results: The size of dentin chips from ProFile, ProTaper and WaveOne was up to 7 µm, 6.5 µm, and 4 µm, respectively. In the surface profile, the width of surface irregularity was measured and Profile, ProTaper and WaveOne was up to 150 µm, 70 µm, and 80 µm, respectively. Completely cleaned root canals were not found. In the middle and apical third of the canals, WaveOne group showed higher smear layer score than ProFile and ProTaper groups (P < 0.05). Conclusion: Within limits of this study, reciprocating motion WaveOne group was not significant difference of shaping ability with the full-sequence ProFile and ProTaper systems except canal clearness of middle and apical third of root canal. When using WaveOne to shaping root canal, thorough root canal irrigation is recommended. (J Dent Rehabil Appl Sci 2014;30(2):121-30)

Micro–Computed Tomography Evaluation of the Preparation of Mesiobuccal Root Canals in Maxillary First Molars with Hyflex CM, Twisted Files, and K3 Instruments

IntroductionThe aim of this study was to describe the canal shaping properties of Hyflex CM, Twisted Files (TF), and K3 rotary nickel-titanium files by using micro–computed tomography in maxillary first molars. MethodsA total of 36 mesiobuccal root canals of maxillary first molars were prepared with Hyflex CM, TF, or K3 system. Micro–computed tomography was used to scan the specimens before and after instrumentation. The volume of untreated canal, volume of dentin removed after preparation, amount of uninstrumented area, and the transportation for the coronal, middle, and apical thirds of canals were measured. ResultsInstrumentation of canals increased their volume and surface area. TF group showed the greatest amount of volumetric dentin removal (P < .05), whereas no significant difference was found in Hyflex CM and K3 groups. There were no significant differences among instrument types concerning uninstrumented area. The TF system produced significantly less transportation than the K3 system in the apical third of canals. No significant difference was found between TF and Hyflex CM instruments relating to apical transportation. ConclusionsIn vitro, Hyflex and TF instruments shaped curved root canals in maxillary first molar without significant shaping errors.