A comparison of canal centering ability of four instrumentation techniques

Morphometric micro-CT study of contralateral mandibular incisors

OBJECTIVES

This study aimed to determine the degree of similarity and symmetry in the anatomy of contralateral mandibular incisors. Three-dimensional (3D) models of extracted teeth were obtained from microtomography (micro-CT) scans. Qualitative and quantitative assessments of the morphology and comparison of contralateral pairs were made. The null hypothesis was that contralateral mandibular incisors could not be considered identical in simple morphometric measurements.

METHODS

Sixty pairs of mandibular incisors were extracted from 30 patients and scanned with micro-CT. Virtual models of the cemento-enamel junction to the root apex were rendered. Parameters such as length, canal width, dentinal thicknesses, tortuosity, centerline length, accessory canals, root canal configurations, and root canal orifice cross-sections were used to compare the teeth. Width and thickness comparisons between paired teeth in the same individual were made by paired t-test (Wilcoxon signed-rank test for variables not normally distributed). An online randomization tool generated randomized pairs (independent of the individual/patient). Subsequently, an unpaired t-test (or Mann-Whitney U test for non-normally distributed parameters) and a correlation analysis were conducted. Canal configurations were classified according to preexisting classification schemes. The number and location of accessory canals and apical foramina were registered and compared.

RESULTS

Utilizing advanced imaging techniques and quantitative analyses, our study establishes that contralateral mandibular incisors exhibit a remarkable degree of symmetry in multiple morphological parameters, including length, canal width, and dentinal thicknesses. The apical third showed a high degree of inter-variability for the contralateral pairs. The rigorous statistical analysis of the normalized parameters by Z-score showed no statistically significant differences between the contralateral mandibular incisors. Comparisons between central and lateral teeth revealed differences in root length but no significant disparity in the distribution of accessory canals. Central teeth, on average, were longer, while accessory canals were distributed relatively evenly between central and lateral teeth.

CONCLUSIONS

The findings of this study further establish the significant similarities between contralateral mandibular incisors, reinforcing their suitability as a reliable substrate for root canal comparison studies.

CLINICAL RELEVANCE

The absence of statistically significant differences between contralateral pairs in normalized parameters underscores their potential as a reliable reference point for root canal comparison studies in clinical dentistry. Furthermore, our findings emphasize the importance of individualized treatment planning, considering the natural symmetry in mandibular incisors to enhance clinical decision-making. This research contributes valuable insights to the field of endodontics, offering a standardized approach to sample selection and enriching the understanding of dental anatomy.

Phase transformation and mechanical properties of heat-treated nickel-titanium rotary endodontic instruments at room and body temperatures

BACKGROUND

The aim of this study was to evaluate the phase composition, phase transformation temperatures, bending property, and cyclic fatigue resistance of different heat-treated nickel-titanium (NiTi) rotary instruments with the same tip diameter and taper at room (RT; 25 ± 1 °C) and body (BT; 37 ± 1 °C) temperatures.

METHODS

Five heat-treated NiTi rotary instruments, HyFlex EDM (EDM), HyFlex CM (CM), Vortex Blue (VB), RE file CT (RE) and JIZAI, and a non-heat-treated NiTi rotary instrument (Mtwo) with a size 40, 0.04 taper were investigated. Temperature-dependent phase transformation was examined with differential scanning calorimetry (DSC). The bending loads of the instruments at RT and BT were evaluated using a cantilever-bending test. Cyclic fatigue resistance at RT and BT was measured using a dynamic test, during which the instruments were rotated in combination with a 2-mm back-and-forth motion in an artificial curved canal, and the number of cycles to failure (NCF) was determined. The results were analyzed using two-way repeated measures analysis of variance, a simple main effect test, and the Bonferroni test (α = 0.05).

RESULTS

DSC results indicated that EDM and Mtwo were primarily composed of martensite/R-phase and austenite, respectively, while the other heat-treated instruments were composed of a mix of martensite/R-phase and austenite at the tested temperatures. Regardless of the temperature setting, the bending loads of heat-treated instruments were significantly lower than those of Mtwo (p < 0.05). EDM showed the lowest bending loads and highest NCF at both temperatures (p < 0.05). CM, VB, and JIZAI showed significantly higher bending loads at BT than at RT (p < 0.05). The NCF of all the heat-treated instruments, except VB, was lower at BT than at RT (p < 0.05). At BT, the NCF of CM, VB, RE, and JIZAI were not significantly higher than that of Mtwo (p > 0.05).

CONCLUSIONS

Heat-treated NiTi instruments exhibited lower bending loads and higher NCF values than Mtwo. However, this tendency was less pronounced at BT than at RT, especially in the NCF values of instruments with a mixture of martensite/R-phase and austenite phases at the tested temperatures.

Evaluation of Canal-centering Ability and Apical Transportation of Hyflex-EDM, OneShape, WaveOne Gold, and Reciproc Files: An Ex Vivo Study

AIM

To evaluate and compare canal-centering ability (CCA), canal transportation (CT), and dentinal crack formation by using Hyflex-electrical discharge machining (EDM), OneShape, WaveOne Gold, and Reciproc single file system in the mesiobuccal root of maxillary first molar at coronal, middle, and apical third using cone-beam computed tomography (CBCT) and scanning electron microscopy (SEM).

MATERIALS AND METHODS

Mesiobuccal roots of 120 freshly extracted maxillary molar teeth were divided into four experimental groups; Hyflex-EDM, OneShape, WaveOne Gold, and Reciproc (n = 30/group). Preinstrumentation scanning was done using CBCT for all samples at coronal one-third (4 mm), middle one-third (8 mm), and apical one-third (12 mm). After cleaning and shaping with standard irrigation protocol, the specimens were again scanned. Canal-centering ability and CT were calculated using pre- and postinstrumentation CBCT values. A scanning electron microscope was used to identify dentinal crack formation.

RESULTS

No significant difference was found for CCA by any of the systems at coronal, middle, and apical third, respectively. However, OneShape was found to have better CCA at the coronal third and WaveOne Gold at the middle and apical third. There was a significant difference in canal transportation at the apical third (p = 0.004) with WaveOne Gold having the least CT followed by Reciproc at the apical third. OneShape resulted in more dentinal cracks in the coronal and middle thirds. Also, Hyflex-EDM was better in the apical third.

CONCLUSION

No difference in CCA was observed between the groups. The lowest values for CT were obtained for WaveOne Gold (similar to Reciproc) whereas both rotary files showed higher values for CT. Also, OneShape showed the most dentinal at all levels. Furthermore, Hyflex-EDM and WaveOne Gold produced the least dentinal cracks at all levels.

CLINICAL SIGNIFICANCE

Given that the Reciprocating file system had the least CT and least dentinal cracks, the clinical success rate of root canal treatment (RCT) with the Reciprocating file system can be a better choice to improve the longevity of root canal-treated teeth.

Nitinol Type Alloys General Characteristics and Applications in Endodontics

A very extensive literature review presents the possibilities and needs of using, in endodontics, the alloys commonly known as nitinol. Nitinol, as the most modern group of engineering materials used to develop root canals, is equilibrium nickel and titanium alloys in terms of the elements’ atomic concentration, or very similar. The main audience of this paper is engineers, tool designers and manufacturers, PhD students, and students of materials and manufacturing engineering but this article can also certainly be used by dentists. The paper aims to present a full material science characterization of the structure and properties of nitinol alloys and to discuss all structural phenomena that determine the performance properties of these alloys, including those applied to manufacture the endodontic tools. The paper presents the selection of these alloys’ chemical composition and processing conditions and their importance in the endodontic treatment of teeth. The results of laboratory studies on the analysis of changes during the sterilization of endodontic instruments made of nitinol alloys are also included. The summary of all the literature analyses is an SWOT analysis of strengths, weaknesses, opportunities, and threats, and is a forecast of the development strategy of this material in a specific application such as endodontics.

An Update on Nickel-Titanium Rotary Instruments in Endodontics: Mechanical Characteristics, Testing and Future Perspective-An Overview

Since the introduction of Nickel-Titanium alloy as the material of choice for the manufacturing of endodontic rotary instruments, the success rate of the root canal therapies has been significantly increased. This success mainly arises from the properties of the Nickel-Titanium alloy: the biocompatibility, the superelasticity and the shape memory effect. Those characteristics have led to a reduction in time of endodontic treatments, a simplification of instrumentation procedures and an increase of predictability and effectiveness of endodontic treatments. Nevertheless, the intracanal separation of Nickel-Titanium rotary instruments is still a major concern of endodontists, with a consequent possible reduction in the outcome rate. As thoroughly demonstrated, the two main causes of intracanal separation of endodontic instruments are the cyclic fatigue and the torsional loads. As results, in order to reduce the percentage of intracanal separation research and manufacturers have been focused on the parameters that directly or indirectly influence mechanical properties of endodontic rotary instruments. This review describes the current state of the art regarding the Nickel-Titanium alloy in endodontics, the mechanical behavior of endodontic rotary instruments and the relative stresses acting on them during intracanal instrumentation, highlighting the limitation of the current literature.

A critical appraisal of research methods and experimental models for studies on root canal preparation

It is the aim of this review to present a critical overview and summary on the contemporary possibilities, limitations and challenges of research related to root canal preparation. Frequently used research tools and contemporary research designs will be presented and discussed critically focussing on shortcomings and benefits with special regard to clinical relevance and scientific evidence. A plethora of experimental set-ups for assessing the shaping of root canals have been described in the endodontic literature using a considerable number of techniques and instruments. Nevertheless, it can be stated that scientific evidence demonstrating the clinical impact of many investigated topics is questionable or even missing. Instead of technical, radiographic and geometrical parameters, further research should focus on biological aspects and clinical evidence of the impact of root canal preparation on the outcome of root canal treatment.

Development of a multi-criteria decision-making-based assessment model for dental material selection: Engine-driven nickel-titanium instruments case study

OBJECTIVES

The aims of this study are (i) to propose specific selection criteria related to NiTi instruments for dental practitioners and (ii) to objectively assess the NiTi instruments.

MATERIALS AND METHODS

The steps of the methodology are as follows: Step 1: "Delphi method" was employed to reach a consensus on criteria defined according to the literature review and a group of panelists. Step 2: "Smart pairwise comparisons" were employed to rank the proposed criteria. Step 3: "Borda voting" was employed to determine the weights of the proposed criteria. Step 4: To determine assessment scores, "Simple Additive Weighting" was employed. Step 5: Reliability and validity checks were made by "simulation."

RESULTS

Specific criteria classified under dimensions were proposed and weighted for the NiTi instrument assessment. In this context, an assessment model was proposed and validated.

CONCLUSIONS

The proposed assessment model for NiTi instruments could aid to make the decision-making process as systematic, transparent, and reproducible as possible not only for dental practitioners but also for healthcare professionals. Also, this proposed model can represent a reference framework for further MCDM studies which can rank or classify materials in medical science.

CLINICAL RELEVANCE

The model proposed in this study can be used to aid decision-making in clinical practice by means assessing the NiTi instrumentation system alternatives for practitioners.

Influence of reciprocating and rotary instrumentation on microbial reduction: a systematic review and meta-analysis of in vitro studies

Objectives

The purpose of this study was to conduct a systematic review and meta-analysis of in vitro studies regarding the effectiveness of reciprocating and rotary instrumentation on microbial reduction in root canals.

Materials and Methods

PubMed, Scopus, Web of Science, the Cochrane Library, and the gray literature were searched through December 2019. Studies comparing the influence of reciprocating and rotary instrumentation on the removal of microorganisms from root canals that quantified the antimicrobial effect were included. Data extraction was completed using a systematic form for data collection. The risk of bias of the studies was evaluated. Standardized mean differences (SMDs) and confidence intervals (CIs) were calculated using a random effects meta-analysis.

Results

Seventeen in vitro studies were included in this systematic review, of which 7 provided adequate data for inclusion in the meta-analysis. Both reciprocating and rotary systems were similarly effective in reducing the microbial load in infected root canals (SMD [95% CI], 0.0481 [-0.271, 0.367]). Three studies showed a low risk of bias, whereas most of the studies (82%) presented a medium risk.

Conclusions

Although both techniques decrease the microbial content (with reductions of 23.32%-88.47% and 23.33%-89.86% for reciprocating and rotary instrumentation, respectively), they are not able to provide complete disinfection of root canals.

Cone-beam Computed Tomographic Analysis of Canal Transportation and Centering Ability of Three Different Nickel-Titanium Rotary File Systems

AIM: The aim of the present study was to compare the canal transportation and centering ability of three rotary nickel-titanium file systems, HyFlex controlled memory, Revo-S, and Mtwo in moderately curved root canals using computed tomography (CT). MATERIALS AND METHODS: Thirty freshly extracted single-rooted teeth having curved root canals with at least 10°–20° of curvature were selected. The teeth were divided into three experimental groups of ten each. After preparation with HyFlex CM (Coltene-Whaledent, Allstetten, Switzerland), Revo-S (Micro-Mega, Besançon, France), and Mtwo (VDW, Munich, Germany) all teeth were scanned using CT to determine the root canal shape. Pre- and post-instrumentation images were obtained at three levels, 3 mm apical, 9 mm middle, and 15 mm coronal above the apical foramen were compared using CT software. Amount of transportation and centering ability were assessed. The three groups were statistically compared with analysis of variance and post-hoc Tukey’s honestly significant difference test. RESULTS: Least apical transportation and higher centering ability were seen in HyFlex CM file system in all the three sections followed by Revo-S, Mtwo file system showed maximum transportation. CONCLUSIONS: According to the present in-vitro study, we can conclude that HyFlex CM rotary file systems showed least canal transportation and highest centering ability as compared to Revo-S and Mtwo file system but there was no statistically significant difference among these file systems (p > 0.05) at coronal, middle, and apical level of root canal.

Comparison of canal transportation and centering ability of manual K-files and reciprocating files in glide path preparation: a micro-computed tomography study of constricted canals

Background

Optimum Glide Path (OGP) is a new reciprocating motion aiming to perform efficient glide path preparation in constricted canals. The aim of this study was to investigate and compare manual and OGP movement in terms of canal transportation and centering ability in glide path preparation of constricted canals.

Methods

Thirty constricted mesial root canals of mandibular molars, with initial apical size no larger than ISO#8, were selected and negotiated with #6–#8 K-files under the microscope. Canals were randomly divided into two experimental groups: Group 1 (MAN, n = 15): Glide path was established by using #10-#15 stainless steel K-files manually; Group 2 (OGP, n = 15): #10-#15 Mechanical Glide Path super-files were used with OGP motion (OGP 90°, 300 rpm). Each instrument was used to prepare only 2 canals (as in one mesial root). Canals were scanned before and after glide path preparation with micro-computed tomography (micro-CT) to evaluate root canal transportation and centering ratio at 1, 3 and 5 mm levels from the root apex. File distortions and separations were recorded. Paired t-test was used to statistically evaluate the data (P < .05).

Results

Group 2 showed a significantly lower transportation value than group 1 at 1-mm and 3-mm levels (P < .05), however the difference at 5-mm level was not significant. There was no significant difference regarding the centering ratio between the groups. Six #10 K-files were severely distorted in group 1, while no file separation or distortion was found in group 2.

Conclusions

OGP motion performed significantly less canal transportation (apical 3 mm) and file distortion during glide path establishment in constricted canals comparing to manual motion, while the centering ability between the two was similar.

Clinical relevance

OGP reciprocating motion provides a safer and efficient clinical approach compared to traditional manual motion in glide path establishment with small files in constricted canals.

Comparative evaluation of canal transportation, centering ability, and dentin removal between ProTaper Gold, One Curve, and Profit S3: An in vitro study

Aim:

The aim of the study was to compare the canal transportation, centering ability, and dentin removal of Profit S3 (PS3), One Curve (OC), and ProTaper Gold (PTG) systems using cone-beam computed tomography (CBCT).

Materials and Methods:

Thirty extracted human single-rooted premolars were used in the present study. Preinstrumentation scanning of all the teeth in arch form was taken using CBCT. To increase standardization, crowns were removed and only teeth measuring 16 mm were included in the study. The samples were randomly divided into three groups, with ten samples in each group; Group I was instrumented with PS3, Group II was instrumented with OC, and Group III – PTG. Postinstrumentation scans were performed, and the two scans were compared to determine canal transportation, centering ability, and dentin removal at 3, 6, and 9 mm, from the apex.

Statistical Analysis:

One-way-ANOVA and the independent t-test were done for the pairwise comparison. The significance level was set at P = 0.05; statistical analysis was performed with SPSS statistics version 20.0 (SPSS Inc., Chicago, IL, USA).

Results:

The mean canal centering ratio and canal apical transportation for PS3, OC and PTG show no statistical difference (P > 0.05). The mean value of dentin removal showed a statistically significant difference between the three groups (P < 0.05). PS3 and OC rotary file showed less removal of dentin compared to PTG (P < 0.00).

Conclusion:

It was evident that PS3, OC, and PTG had no statistically significant difference when analyzed based on canal transportation and canal centering ratio. However, there was a significant difference among the three groups comparing the removal of dentin. PS3 and OC rotary file showed less removal of dentin compared to PTG.

An Arithmetic Crown-down Dynamic Tactile Instrumentation Technique: A Case Report of an S-shaped Root Canal

The preparation of severely curved S-shaped double-curved root canals can be technically challenging. A novel root canal instrumentation technique is proposed, which modifies 2 techniques: the McSpadden crown-down technique and the tactile controlled activation technique. In the McSpadden crown-down technique, the root canal is divided into 2 portions: the coronal zone and the apical zone. However, rather than focusing on the length of file engagement, a formula is proposed to calculate the maximum insertion depths of higher tapered instruments to prevent overflaring of the canal and preserve pericervical dentin. Tactile-controlled activation involves activating martensitic nickel-titanium rotary files upon engagement and then immediately withdrawing the files. The proposed technique recommends 3 apical strokes after the initial engagement before withdrawal to minimize instrumentation time. This novel technique is described in a case report involving the management of an S-shaped double-curved maxillary lateral incisor. The technique presents a new method of crown-down instrumentation that prevents overflaring and avoids instrument separation.

Comparison of antibacterial effectiveness of three rotary file system with different geometry in infected root canals before and after instrumentation-a double-blinded randomized controlled clinical trial

Introduction

To compare the antibacterial effectiveness of three rotary file systems i.e., ProTaper Next, ProTaper Gold and XP-endo Shaper in root canals of teeth with asymptomatic apical periodontitis by using the real-time polymerase chain reaction.

Materials and methods

Root canals from single or multi-rooted teeth (straight canals) with necrotic pulps and asymptomatic apical periodontitis were instrumented using either ProTaper Next (n = 20), ProTaper Gold (n = 20) and XP-endo Shaper (n = 20) under irrigation with 3% sodium hypochlorite. Samples obtained before and after instrumentation were subjected to DNA extraction, amplification and quantitation of total amount of bacteria by using the real-time polymerase chain reaction.

Results

Samples were taken before preparation (S1) were positive for presence of bacteria, with mean numbers of 9.94 × 10⁷, 20.4 × 10⁷ and 9.20 × 10⁷ bacterial cells for the ProTaper Next, ProTaper Gold and XP-endo Shaper groups, respectively. After preparation (S2) with ProTaper Next, ProTaper Gold, and XP-endo Shaper, root canals still had bacteria with mean counts of 11.8 × 10⁵, 87.2 × 10⁵ and 4.52 × 10⁵ bacterial cells, respectively. Both XP-endo Shaper (99.50%) and ProTaper Next (98.81%) were effective in reducing total bacterial count, and there was no statistically significant difference between them (P > 0.05). XP-endo Shaper succeeded in reducing total bacterial count than ProTaper Gold (95.72%) and there exists statistically significant difference between them (P < 0.05).

Conclusions

XP-endo Shaper was highly effective in reducing total bacterial count from root canals of teeth with asymptomatic apical periodontitis than ProTaper Gold. ProTaper Next also showed improved microbial reduction percentage as compared with ProTaper Gold.

Current Trends in Use and Reuse of Nickel-Titanium Engine-driven Instruments: A Survey of Endodontists in the United States

INTRODUCTION

Information is scarce regarding current usage practices of nickel-titanium (NiTi) engine-driven instruments in clinical practice. Therefore, the specific purpose of this survey was to assess trends among endodontists regarding the use and reuse of NiTi instruments.

METHODS

A 16-question survey was sent by e-mail to about 4000 active members of the American Association of Endodontists. Data were collected over a 6-month period and compared using chi-square tests.

RESULTS

A total of 957 surveys were collected (response rate = 23%). Of the respondents, 40.2% worked in solo practices; among them, there were significantly fewer recent graduates (<10 years) compared with those who graduated more than 10 years ago. Furthermore, 41.7% were in a group practice, 4.3% in corporate practice, 10.7% in university settings, and 3% in the military. Overall, 98.3% of respondents reported using NiTi instruments. Respondents who graduated less than 25 years ago use NiTi instruments significantly more (99%) than those who graduated more than 25 years ago (92.6%). Although 22.9% of respondents buy presterilized instruments, 41.6% sterilize them before use, and 35.5% do not sterilize new instruments before use; dental officers in the military reported that they use sterile new instruments in 100% of cases. NiTi instruments were reused by 74% of respondents. The 2 largest segments of the specialist endodontic instrument market belonged to Dentsply (York, PA; 56.9%) and EdgeEndo (Albuquerque, NM; 28.8%).

CONCLUSIONS

There are significant differences in the use of NiTi instruments among types of practice and years since graduation. There were noticeable changes compared with findings reported about 10 years ago.

Effect of Sterilization on Cyclic Fatigue Resistance of Proflexendo Endodontic Rotary Files

Background:

Proflexendo file (Nexen, Houston, TX, USA) is a recently developed, novel nickel-titanium rotary file. However, several physical properties of the Proflexendo system remain to be investigated.

Objectives:

The aim of this study was to determine the effect of sterilization on cyclic resistance of Proflexendo files.

Material and Methods:

A total of 120 unused Proflexendo rotary files (40 each of file sizes 40/0.04, 30/0.04 and 20/0.06) were used in this study. Each set of files was subdivided into four groups of ten files. Group 1 did not undergo any sterilization (control), Group 2 underwent two rounds (2×) of sterilization, Group 3 five rounds (5×) and Group 4 ten rounds (10×). Cyclic fatigue resistance was tested using an artificial canal with a 5-mm radius curve.

Results:

The nonsterilized size 30/0.04 files had the highest cycles to failure, followed by the nonsterilized size 40/0.04 and 20/0.06 files (P < 0.001). With increasing rounds of sterilization, cycles to failure reduced for sizes 40 (2×, 5× and 10×) and 30 (2×) files compared with nonsterilized sizes 40 (P < 0.05) and 30 files (P < 0.001), respectively.

Conclusion:

Under the conditions of the current study, the results provide preliminary evidence that autoclave sterilization of Proflexendo rotary files reduced their cyclic fatigue resistance, except for size 20 (2× and 5×) and 30 (10×) files, in which resistance increased. Single use of this file is recommended to reduce the risk of separation.

The influence of kinematics of engine-driven nickel-titanium instruments on root canal shape assessed by micro-computed tomography: a systematic review

AIM

To evaluate if the kinematics of engine-driven instruments affect the root canal shape.

METHOD

The systematic review was registered in PROSPERO (CRD 42017077043). A broad search was performed for articles published before 26 September 2018 in the electronic databases: pubmed, scopus, web of science and Lilacs using MeSH and free terms. Only in vitro studies with human teeth that evaluated root canal shape by volume, surface area and unprepared surface area using reciprocating and rotary system assessed by micro-computed tomography were included. A modified checklist for randomized controlled trials from the Joanna Briggs Institute was used to assess the risk of bias.

RESULTS

Twenty-one articles were selected. According to quality assessment, all studies were considered 'moderate methodological quality'. Eighteen articles analysed volume increase, only four studies showed statistically significant difference, three indicating that the reciprocating movement obtained a greater increase in volume than the rotary system and one rotary system obtained a greater increase. Twelve studies analysed surface area, only three studies showed statistically significant difference, two presented a reciprocating system revealing greater amount of surface area and one showed a rotary system obtained a greater amount of surface area. Ten articles evaluated unprepared surface area, two studies that analysed total length, one study presented that the rotary system revealed lower unprepared surface area while another study showed reciprocating with less unprepared area. One study analysed middle and apical third, and observed that the rotary system presented lower unprepared surface area in the middle third.

CONCLUSIONS

Both the rotary and reciprocating kinematics produce changes in volume and surface area and leave unprepared areas in the root canal, however reciprocating system showed greater increase of volume and surface area, while the rotary system maintains less unprepared surface area.

An Ex Vivo Evaluation of Antimicrobial Efficacy of Root Canal Preparation With Hand K-Files, Hand Pro Taper, and Pro Taper Rotary Files

Background:

Microorganisms are considered to be the primary cause behind persistent pulpoperiapical pathologies as well as endodontic failures. It has been found that Enterococcus faecalis is one of the most commonly isolated organisms in failed endodontic treatment. Proper and appropriate mechanical instrumentation is necessary to eradicate these microorganisms.

Aims and Objectives:

The aim of this study was to compare antimicrobial efficacy of various root canal instrumentation techniques. This study was designed to compare antimicrobial efficacy of root canal preparation using hand K-files, hand Pro Taper files, and Pro Taper rotary files.

Materials and Methods:

Forty intact maxillary premolars extracted for orthodontic reasons were used. After extirpation of pulp, teeth are decoronated and autoclaved. Then the root canals were infected with E. faecalis suspension and the teeth were incubated at 37°C for 24 h. Thereafter the teeth were divided into five groups and were prepared using the following instruments: group 1 (hand K-files), group 2 (hand Pro Taper files), group 3 (Pro Taper rotary files), group 4 (Control I; treatment consists of irrigation with 1 mL of sterile physiological saline with no instrumentation), and group 5 (Control II; teeth received no treatment at all). Before and after treatments, samples were taken from the root canals for culture and were transferred to physiological saline. Results were evaluated after 24-h incubation in selective culture medium.

Results:

The results showed that the teeth prepared with Pro Taper rotary files showed significant reduction in number of bacteria from the root canals.

Comparative evaluation of instrumentation timing and cleaning efficacy in extracted primary molars using manual and NiTi rotary technique - Invitro study

Aim

To compare the timing of instrumentation and cleaning efficacy between manual K files and NiTi rotary files in extracted primary molars.

Study design

in-vitro study was conducted in 90 root canals of extracted primary molars which were subdivided in three groups viz. Control (No instrumentation), Manual (K files), Rotary (ProFiles) with 30 canals in each group. Mesiobuccal (MB) and Mesiolingual (ML) canals of mandibular molars, and MB and Distobuccal (DB) canals of maxillary molars were included in the test group whereas Distal canals in mandibular molars and Palatal canals in maxillary molars were included in the control group.

Method

Teeth were mounted and canals were injected with India ink to stain the canal walls. Canal preparation was done as per the group. After instrumentation, teeth were demounted, decalcified and cleared to make them transparent for scoring according to the extent of removal of India ink. Timing of instrumentation and cleaning efficacy of canals in coronal, middle and apical thirds were assessed in each sample.

Results

Mean timing of instrumentation in rotary group was 3.54 ± 1.14 min and 4.32 ± 1.04 min in manual group. Mean cleaning efficacy scores in manual and rotary groups were 2.03 and 1.66 in coronal third, 1.08 and 1.18 in middle third and 0.67 and 1.08 in apical third respectively. Inter-group comparisons showed no statistically significant difference in cleaning efficacy among test groups in all thirds of root canals.

Conclusion

NiTi rotary technique has comparable cleaning efficacy, with significantly less timing of instrumentation compared to manual K-files.

Cone-beam Computed Tomographic Analysis of Canal Transportation and Centering Ability of Single-file Systems

INTRODUCTION

The purpose of this study was to compare canal transportation and the centering ability of Reciproc (VDW, Munich, Germany), WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), and EdgeFile (EdgeEndo, Albuquerque, NM) rotary systems using cone-beam computed tomographic imaging.

METHODS

Ninety mesiobuccal mandibular first molar uncalcified canals with at least a 19-mm length, a canal curvature of 15°-30° (the Schneider method), and a mature apex were selected. Canals were randomly divided into 3 groups of 30 teeth, and canal preparation with the Reciproc, WaveOne, and EdgeFile systems was performed according to the manufacturers' instructions. Cone-beam computed tomographic images were taken before and after instrumentation in the same position. Apical transportation was calculated in the distances of 2, 3, and 4 mm from the apex. Kruskal-Wallis and Mann-Whitney U tests were used to statistically analyze the data.

RESULTS

The mean canal transportation was significantly lower with EdgeFile (P < .001) followed by the WaveOne rotary system. Moreover, the centering ability of the EdgeFile system was higher than that of the WaveOne and Reciproc systems.

CONCLUSIONS

The EdgeFile rotary system showed the lowest transportation in both the mesiodistal and buccolingual directions and the highest centering ability. The Reciproc system showed the highest transportation and the lowest centering ability.

Methods for measurement of root canal curvature: a systematic and critical review

The assessment of root canal curvature is essential for clinical and research purposes. This systematic review presents an overview of the published techniques for the measurement of root canal curvature features using imaging and to provide a critique of their clinical application. A database search in PubMed, PubMed Central, Embase, Scopus, EBSCO Dentistry & Oral Sciences Source and Virtual Health Library was conducted, using appropriate key words to identify measurement methods for root canal curvatures. The search strategy retrieved 10594 records in total, and 31 records fulfilled the inclusion criteria. From 2D image acquisitions, eleven studies measured exclusively the angle of curvature, an additional thirteen measured other curvature features (level, height, radius, length and shape). Seven reports described methods from 3D imaging (CBCT, μCT). Root canal curvatures should be measured, for clinical proposes, to facilitate endodontic treatment planning, and in research, to reduce the risk of selection bias. This review has revealed that there are many methods described in the literature; however, no consensus exists on which method should be used. Some of the methodologies have potential clinical translation, whereas others are suitable for research purpose only, as they require a specific software or radiographic exposure in the mesiodistal direction.

Computed tomography evaluation of root canal transportation using ProTaper, Race and Sendoline rotary systems: an ex vivo study

Background

This ex vivo study aimed to compare transportation of the mesiobuccal root canal of mandibular first molars instrumented with ProTaper, Race and Sendoline rotary systems using cone beam computed tomography (CBCT).

Materials and methods

Forty-five mesiobuccal canals of mandibular first molars were randomly divided into three groups of 15. Root canals in each group were instrumented with the ProTaper, Race or Sendoline rotary system according to the manufacturers’ instructions. Root canal preparations were performed by one operator, while root canal wall measurements were made by another operator blinded to the group allocation of teeth. The pre- and post-chemomechanical preparation CBCT scans were obtained and evaluated at 3, 6 and 9 mm levels from the apex. The amount of root canal transportation at these levels was calculated. Data were analyzed using SPSS version 17 via Mann–Whitney and Kruskal–Wallis tests. P<0.05 was considered significant.

Results

No significant difference was noted in canal transportation among the groups (P>0.05), but ProTaper showed the least and Sendoline caused the most canal transportation in the coronal third.

Conclusion

ProTaper, Race and Sendoline rotary systems are not significantly different in terms of canal transportation. Although all rotary files cause root canal transportation, ProTaper and Race showed the least amount of canal transportation in the coronal and apical thirds, respectively.

Canal Aberration Assessment in Simulated Root Canals: a Comparative Study

Aim:

The aim of this study was to compare time of preparation and canal aberrations in a simulated root canals after using three different rotary systems: Endostar E5, Endostar E3 and T One File Gold.

Materials and Methods:

A total of 90 endodontic training blocks were used in this study and divided into three groups consisting of 30 each (n = 30). Blocks processing was performed by thirty dentists without any prior experience in rotary instrumentation techniques. In the first group blocks were prepared using Endostar E5, in second one with Endostar E3 and in third one with T One File Gold system. The preparation time was measured. The postoperative image of each block was taken by stereomicroscope and canal aberrations (ledge and instrument fracture) was recorded. Statistical analysis was done by SPSS software.

Results:

Instrumentation with T One File Gold system is significantly faster compared to instrumentation with Endostar E5 and Endostar E3 systems (p <0.05). There are no statistically significant differences in the type and number of procedural errors between Endostar E5, Endostar E3 and T One File Gold systems when the operators have no previous experience in rotary instrumentation techniques.

Conclusion:

Under the conditions of this study, the incidence of examined canal aberrations were similar for all tested systems. The preparation time was significantly shorter with single file system.

Apical transportation of ProGlider and ProTaper Next activated with different motions

PURPOSE

The aim of this study was to investigate the apical transportation of the ProGlider and ProTaper Next using 3 different motions (150° clockwise [CW]; 0° counter clockwise [CCW], 270° CW-30° CCW; and [360° CW] continuous rotation).

MATERIALS AND METHODS

36 simulated, curved, plastic training blocks were randomly distributed into 3 groups for treatment according to the movement kinematics used for ProGlider (Dentsply Maillefer) followed by ProTaper Next (Dentsply Maillefer) instruments (n = 12): 150° CW-30° CCW, 270° CW-30° CCW, and 360° CW (continuous rotation). Pre- and post-instrumentation photographs were taken from the root canals in a standardized manner. Root canal transportation was calculated at 1, 2, 3, 4, and 5 mm from the apical terminus of the canal. Data were analyzed using a Kruskal-Walis H test (p = .05).

RESULTS

At the 1- and 2-mm levels, both reciprocating motions (150° CW-30° CCW and 270° CW-30° CCW) resulted in less transportation than those of continuous rotation (p<.05). However, there were no significant differences between the groups at the 3-, 4-, and 5-mm levels (p>.05).

CONCLUSIONS

Both reciprocating motions were found to have less canal transportation than the continuous rotation group at the 1- and 2-mm levels. This is the first study about the use of the ProGlider and ProTaper Next activated by different motions. Reciprocating motion can be beneficial for ProGlider and ProTaper Next to reduce transportation of root canals.

Evaluation of canal transportation after preparation with Reciproc single-file systems with or without glide path files

Background:

Canal transportation is a common sequel caused by rotary instruments.

Aims:

The purpose of the present study is to evaluate the degree of transportation after the use of Reciproc single-file instruments with or without glide path files.

Methods:

Thirty resin blocks with L-shaped canals were divided into three groups (n = 10). Group 1 - canals were prepared with Reciproc-25 file. Group 2 - glide path file-G1 was used before Reciproc. Group 3 - glide path files-G1 and G2 were used before Reciproc. Pre- and post-instrumentation images were superimposed under microscope, and resin removed from the inner and outer surfaces of the root canal was calculated throughout 10 points.

Results:

Statistical analysis was performed with Kruskal–Wallis test and post hoc Dunn test. For coronal and middle one-thirds, there was no significant difference among groups (P > 0.05). For apical section, transportation of Group 1 was significantly higher than other groups (P < 0.05).

Conclusion:

Using glide path files before Reciproc single-file system reduced the degree of apical canal transportation.

Comparative study of ProTaper gold, reciproc, and ProTaper universal for root canal preparation in severely curved root canals

Aim

The aim of this study is to evaluate the root canal transportation, centering ability, and instrumentation times with the ProTaper Gold (Dentsply Tulsa Dental, Tulsa, OK, USA), Reciproc (VDW, Munich, Germany), and ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) using cone-beam computed tomography (CBCT).

Materials and Methods

Thirty mesial root canals of mandibular first molars with curvature angles of 35°-70° and radii of 2-6 mm were included in the study. Root canal instrumentation was performed up to F2 or R25. The instrumentation times were recorded. CBCT scanning was performed both pre- and post-instrumentation. Root canal transportation and the centering ratio were calculated for groups, and the data were analyzed using a one-way ANOVA and least significant difference post hoc tests for the instrumentation time, root canal transportation, and centering ratio at the 95% confidence level (P = 0.05).

Results

At 3, 5, and 7 mm levels, there was no significant difference in the root canal transportation and centering ratio among the groups (P > 0.05). There were significant differences between the Reciproc and ProTaper Universal groups in the instrumentation times (P < 0.05).

Conclusion

Root canal transportation and the centering ratio with the ProTaper Gold were similar to those obtained with the ProTaper Universal and Reciproc.

Comparison of cleaning Efficacy and Instrumentation Time between Rotary and Manual Instrumentation Techniques in Primary Teeth: An in vitro Study

Objectives: The aim of this study was to compare the cleaning efficacy and instrumentation time between manual Hedstrom files (H-files) and rotary Mtwo files in primary molar root canals.

Materials and methods: A total of 90 primary root canals were selected using standardized radiographs. The canals were injected with India ink with 30 gauge insulin syringe and divided into three groups. Group I―30 root canals instrumented with H-files, group II―30 root canals instrumented with Mtwo files, and group III―control group in which no canal instrumentation was done. The teeth were cleared in various solutions and then observed under a stereomicroscope.

Results: No significant difference was seen in cleaning efficacy between H-files and Mtwo files in coronal, middle, and apical thirds of the root canal. The instrumentation time recorded for H-files (3.41 ± 0.38 minutes) was significantly less than that of Mtwo files (4.81 ± 0.52).

Conclusion: Although there was no significant difference in cleaning capacity, further studies should be carried out using the single file systems.

How to cite this article: Katge F, Chimata VK, Poojari M, Shetty S, Rusawat B. Comparison of cleaning Efficacy and Instrumentation Time between Rotary and Manual Instrumentation Techniques in Primary Teeth: An in vitro Study. Int J Clin Pediatr Dent 2016;9(2):124-127.

Cone-Beam Computed Tomography Assessment of Root Canal Transportation by Neoniti and Reciproc Single-File Systems

Introduction:

The aim of this in vitro study was to compare the canal transportation of two single-file engine-driven systems, Neoniti and Reciproc, using cone-beam computed tomography (CBCT).

Methods and Materials:

Forty-five non-calcified roots with mature apices and apical curvature of 15-30 degrees were selected from extracted human maxillary molars for this study. Samples were randomly divided into two groups (n=20) and a control group (n=5) and canal preparation with either system was performed according to manufacturers' instructions. Pre- and post-instrumentation CBCT images were captured and the amount of canal transportation within the files was calculated at levels of 3, 4, and 5 mm from the apex. The independent sample t-test was used to analyze the statistical significance between the two groups. The level of significance was defined at 0.05.

Results:

Reciproc created more canal transportation compared to Neoniti in both mesiodistal and buccolingual directions. The difference between the two systems was statistically significant in all evaluated distances from the apex (P<0.001). During this study fracture of one file (25/0.08) in the Neoniti group occurred.

Conclusion:

Neoniti and Reciproc systems have significant difference in terms of creating canal transportation. Reciproc created more canal transportation in buccolingual and mesiodistal dimensions.

Rotary endodontics in primary teeth - A review

Endodontic treatment in primary teeth can be challenging and time consuming, especially during canal preparation, which is considered one of the most important steps in root canal therapy. The conventional instrumentation technique for primary teeth remains the "gold-standard" over hand instrumentation, which makes procedures much more time consuming and adversely affects both clinicians and patients. Recently nickel-titanium (Ni-Ti) rotary files have been developed for use in pediatric endodontics. Using rotary instruments for primary tooth pulpectomies is cost effective and results in fills that are consistently uniform and predictable. This article reviews the use of nickel-titanium rotary files as root canal instrumentation in primary teeth. The pulpectomy technique is described here according to different authors and the advantages and disadvantages of using rotary files are discussed.

Cone-beam Computed Tomography Evaluation of Root Canal Preparation using Various Rotary Instruments: An in vitro Study

AIM

To evaluate the remaining dentin thickness of teeth after cleaning and shaping the root canal using three rotary instrumentation technique using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This in vitro study is being done with 30 premolar samples with 20' curvature. The study is divided into three groups a CBCT was taken to measure the shortest distance from the root canal outline to the closest adjacent root surface was measured at each level from the cementoenamel junction (CEJ) (1,3, 5 and 7 mm) before and after root canal instrumentation. The purpose of this study was to compare the effects of different instruments used to prepare curved root canals on the remaining cervical dentin thickness and total amount of dentin removed from root canals during instrumentation by using multi-slice CBCT. The remaining dentin thickness is very much necessary for the success rate of root canal treatment. However, this study helps to prove that a conservative preparation with a sound remaining dentin thickness is much more advisable.

RESULT

It was observed that there was a significant difference at 1 and 3 mm (p < 0.05) and at 5 and 7 mm there was no significant difference ( p > 0.05). Mtwo has removed less amount dentin when compared to ProTaper Universal and ProTaper Next system at 1 and 3 mm.

CONCLUSION

Under the conditions of the study, we concluded that ProTaper Universal and ProTaper Next should be used judiciously, as it causes higher thinning of root dentin of the root when compared with Mtwo.

Cyclic fatigue resistance of two nickel-titanium instruments in different curving angles: a comparative study

The cyclic resistance of ProTaper Universal (size 25/08) and ProTaper Next (size 25/06) instruments was compared in artificial canals with different curvatures in this study. A total of 30 ProTaper Universal and 30 ProTaper Next instruments were divided into 6 groups (n = 10) and were operated into artificial canals with 3 different angles of curvature (45°, 60°, 90°). The canal length was kept consistent in this study. The number of cycles to fracture (NCF) was counted until file fracture occurred, at which point, the length of the fragment was measured. The data were analyzed statistically using ANOVA complemented by the Tukey test (p < 0.05). Cross sections of the fractured files were scanned by an electron microscope. In the fatigue test, the ProTaper Next displayed more resistance in 45° and 60° canals (p < 0.05), whereas ProTaper Universal exhibited a better operability in 90° canals (p < 0.05). The average length of the fragments from ProTaper Next was significantly shorter than that from ProTaper Universal in 90° canals (p < 0.05). The cross sections of the fractured surfaces became flatter when the curvature angles decreased from 90° to 45°. ProTaper Next was more reliable when shaping in curved canals, whereas ProTaper Universal was more sui for the preparation of root canals with severe curvatures.

A Comparison of Canal-centering ability of Two Nickel-Titanium Rotary Systems with Nickel Hand Instrumentation with Stainless Steel Hand Instrumentation in 10 to 25° Curved Canals using Kuttler's Cube

AIMS

The purpose of this study was to compare the canal centering abilities of rotary nickel-titanium (NiTi) files (ProFile 0.04 and 0.06 and Lightspeed LSX) and NiTi hand K-files in 10° to 25° curved canals. This was compared with the canal centering ability of stainless steel hand K-files using Kuttler's endodontic cube.

SETTINGS AND DESIGN

The teeth with a 10° to 25° of clinical mesiodistal curvature were used for this study. Each tooth was immersed in methylene blue dye for a period of 10 seconds, as recommended by Kuttler.

MATERIALS AND METHODS

The study sample comprised of 60 intact freshly extracted single rooted human mandibular premolars. The radiographs were traced on a tracing paper and the canal curvature was determined according to methodology introduced by Schneider.

STATISTICAL ANALYSIS USED

The statistical package SPSS PC + (Statistical package for social service, Version 4.01) was used for analysis.

RESULTS

Overall, Lightspeed LSX instruments showed superior canal centering ability and performed better than Profile series, hand NiTi K-files and hand stainless steel K-files.

CONCLUSION

The endodontic cube can be used as an effective method for analyzing the canal-centering ability of different endodontic instruments. Both the NiTi rotary instruments showed superior canal-centering ability than NiTi and stainless steel hand K-files. How to cite this article: Swarnkar A. A Comparison of Canal-centering ability of Two Nickel-Titanium Rotary Systems with Nickel Hand Instrumentation with Stainless Steel Hand Instrumentation in 10 to 25° Curved Canals using Kuttler's Cube. Int J Clin Pediatr Dent 2014;7(3):157-162.