Glide Path Management with Single- and Multiple-instrument Rotary Systems in Curved Canals: A Micro–Computed Tomographic Study

Glide Path in Endodontics: A Literature Review of Current Knowledge

The introduction of nickel-titanium rotary instruments revolutionized shaping procedures as they were able to produce a well-tapered preparation while reducing operator fatigue. The major drawback of rotary instruments was the high risk of fracture due to bending and torsional stress. Thus, the creation of a glide path has been advocated and recommended by most rotary instrument manufacturers. The aim of the present review is to summarize existing knowledge on glide path preparation and identify areas where further research is needed. The primary goal is to provide a comprehensive overview of the techniques and instruments used in glide path preparation, highlighting their advantages and limitations. The secondary goal is to explore the effect of glide path creation on the overall success of endodontic treatment, particularly in terms of reducing procedural errors and improving treatment outcomes. An online search on PubMed, ScienceDirect, UCLA, and Scopus databases was conducted, and 116 articles were identified. Eligible articles were divided into nine categories based on what they researched and compared. The categories included centering ability and/or root canal transportation, cyclic fatigue resistance, glide path and shaping time, tortional stress resistance, apical extrusion of debris and/or bacteria, defects in dentine walls, file separation, postoperative pain assessment, and scouting ability and performance. Establishing a glide path reduces root canal transportation, especially with rotary methods. Reciprocating and heat-treated files offer higher fatigue resistance and shorter preparation time. Instruments with shorter pitch lengths have greater torsional strength. Preparation and coronal preflaring reduce apical debris and bacteria. Glide paths do not affect dentine microcracks, file separation, or defects but reduce immediate postoperative pain and improve cutting ability. Randomized trials are needed to assess their impact on treatment outcomes.

Impact of Different Glidepath Techniques on the Overall Performance of WaveOne Gold in an Artificial S-Shape Canal

OBJECTIVES

The article's aim is to test if rotary or reciprocating glide path influences the overall performance of WaveOne Gold in S-shaped canals.

METHODS

Sixty endo training blocks with an S-shape curvature were divided into three groups based on the glide path method used: no glide path; glide path preparation with ProGlider; glide path preparation with WaveOne Gold Glider. All blocks were then shaped with WaveOne Gold Primary. The time for shaping, the incidence in reaching working length and the number of pecking motions were recorded. ANOVA with Turkey's test was used, and the p-value was set to 0.05.

RESULTS

WaveOne Gold Primary reached working length faster in the control group when comparing total working times. No significant differences in the ability of the WaveOne Gold Primary to reach working length in all groups (p > 0.05). The mean number of pecking motions was higher in the control group compared to other groups.

CONCLUSIONS

No significant differences in the time needed to achieve a glide path between Proglider and WaveOne Gold Glider. WaveOne Gold Primary can shape a double curved canal faster if a glide path is present but takes less time to reach length if it is the only file used. No difference in the ability to reach working length.

Comparison of the effect of different glide path files on amount of apically extruded debris in curved root canals

It is essential to create a glide path before root canal preparation with nickel-titanium rotary files to avoid file breakage and preserve the original canal structure. The aim of this study was to compare the amount of apically extruded debris after using different glide path files. A total of 96 first mandibular molars with curved mesial roots were randomly divided into six groups (n = 16) which are K-files, Proglider, R-Pilot, TruNatomy Glider, WaveOne Gold Glider and group without a glide path. Apically extruded debris was measured after glide path and canal preparation. The highest amount of debris was found in the control group without a glide path and using a glide path file caused less debris and significant differences were observed between R-Pilot, TruNatomy Glider, ProGlider, WaveOne Gold Glider and K-file groups. It may be recommended to create a glide path before root canal shaping to reduce the amount of extrusion debris from the apical. Especially in curved and narrow root canals, it is recommended to use an R-Pilot file before root canal shaping in order to reduce the amount of apically extruded debris.

3D-Printed Teeth in Endodontics: Why, How, Problems and Future-A Narrative Review

Three-dimensional printing offers possibilities for the development of new models in endodontics. Numerous studies have used 3D-printed teeth; however, protocols for the standardization of studies still need to be developed. Another problem with 3D-printed teeth is the different areas of literature requested to understand the processes. This review aims to gather evidence about 3D-printed teeth on the following aspects: (1) why they are advantageous; (2) how they are manufactured; (3) problems they present; and (4) future research topics. Natural teeth are still the standard practice in ex vivo studies and pre-clinical courses, but they have several drawbacks. Printed teeth may overcome all limitations of natural teeth. Printing technology relies on 3D data and post-processing tools to form a 3D model, ultimately generating a prototype using 3D printers. The major concerns with 3D-printed teeth are the resin hardness and printing accuracy of the canal anatomy. Guidance is presented for future studies to solve the problems of 3D-printed teeth and develop well-established protocols, for the standardization of methods to be achieved. In the future, 3D-printed teeth have the possibility to become the gold standard in ex vivo studies and endodontic training.

Effect of kinematics on the torque/force generation, surface characteristics, and shaping ability of a nickel titanium rotary glide path instrument: an ex-vivo study

AIM

To evaluate the effect of various rotational motions on the torque/force generation, surface wear, and shaping ability of the ProGlider glide path instrument (Dentsply Sirona).

METHODOLOGY

Mesiobuccal and mesiolingual canals of mandibular molars were selected based on the canal volume, length, angle of curvature (25°-40°), and radius of curvature (4-8 mm) after micro-computed tomographic scanning. The samples were randomly assigned to four groups (n = 13, each) according to movement kinematics [continuous rotation (CR; 300 rpm), optimum torque reverse motion (OTR; 180° forward and 90° reverse when torque > 0.4 N·cm), time-dependent reciprocal motion (TmR; 180° forward and 90° reverse), and optimum glide path motion (OGP; a combination of 90° forward, 90° reverse, 90° forward, and 120° reverse)]. Instrumentation was performed with an automated root canal instrument and torque/force analysing device. Maximum torque/force values, canal volume changes, and canal-centring ratios at 1, 3, 5, and 7 mm were evaluated. Surface defects (pits, grooves, microcracks, blunt cutting edges, and disruption of cutting edges) and spiral distortion on the ProGlider instrument were scored at the tip and 5 mm short of the tip before and after five consecutive uses with scanning electron microscopy. The Kruskal-Wallis test followed by Dunn's post-test with Bonferroni correction and Wilcoxon signed-rank test were used to analyse the data (α = 0.05).

RESULTS

OGP generated significantly less clockwise torque and greater upward force than other groups (P < 0.05). OGP resulted in significantly fewer surface defects than CR (P < 0.05). In OGP and CR, the tip exhibited more surface defects than 5 mm short of the tip (P < 0.05). CR resulted in greater volume changes than OGP and TmR (P < 0.05) and greater centring ratios (i.e., more deviation) than OGP at 1 mm and OTR at 3 mm (P < 0.05).

CONCLUSIONS

Under laboratory conditions using the ProGlider instrument, OGP generated significantly less clockwise torque and greater upward force than the other rotatory motions. OGP generated fewer superficial defects than CR, and the three modes of reciprocal rotation better maintained the apical curvature of root canals than CR with the ProGlider instrument.

Comparison of Canal Transportation and Centering Ability of One-G, EdgeGlidePath, and Neolix: A MicroComputed Tomography Study of Curved Root Canals

Aims

A glide path is created prior to root canal instrumentation by nickel-titanium (NiTi) rotary files to increase the efficiency and safety of cleaning and shaping. This study aimed to assess root canal transportation in use of different glide path files in curved canals.

Materials and Methods

30 sound mesiobuccal root canals of mandibular molars with 20° to 40° curvature were selected and randomly assigned to 3 groups of EdgeGlidePath (EGP, EdgeEndo), One-G (Micro-Mega), and Neolix (Neoniti). The specimens were scanned before and after glide path creation by microcomputed tomography (micro-CT). The pre- and postoperative micro-CT scans were superimposed, and the degree of canal transportation and centering ratio were measured at 1, 3, 5, and 7 mm distances from the apical foramen. Statistical Analysis. The data were analyzed by two-way and one-way ANOVA.

Results

The effects of distance from the apical foramen and instrument type and the interaction effect of the two were not significant on the centering ability of the files or canal transportation.

Conclusion

EdgeGlidePath, One-G, and Neolix files fabricated from the conventional NiTi alloy or heat-treated M-Wire alloy showed similar performance regarding centering ability and canal transportation in glide path preparation in curved canals.

Comparison of Apical Extrusion of Bacteria After Glide Path Preparation Between Manual K File, One G Rotary, and WaveOne Gold Glider Reciprocation Preparations

Objective:

To compare the amount of apically extruded bacteria between hand-filed preparations, rotary and reciprocation glide path preparations in curved canals of extracted teeth infected with Enterococcus faecalis.

Methods:

Forty mandibular first molar teeth were decoronated, fitted into rubber stoppers and fixed onto glass vials. The mesiobuccal canals from mandibular first molar teeth were infected with Enterococcus faecalis, then randomly assigned to one of five groups for glide path preparation: manual stainless-steel file (K-files), rotary file (One G), reciprocating file (WaveOne Gold Glider) and two control groups. After glide path preparation, 0.01 mL of saline was taken from the experimental vials. The solution was plated on tryptic soy agar and colonies of bacteria were counted as colony-forming units. The results were analysed statistically using Kruskal-Wallis and post hoc Mann-Whitney U tests.

Results:

The manual K-file group was associated with significantly more bacteria extrusion compared to the rotary and reciprocating groups (P<0.05). However, no significant difference occurred between rotary and reciprocation instruments.

Conclusion:

All instrumentation techniques resulted in a measurable amount of apical extrusion of bacteria. Manual K-files extruded the highest quantity of bacteria compared to One G rotary file and WaveOne Gold Glider reciprocation file during glide path preparation.

Glide path enlargement of curved molar canals using HyFlex EDM glide path file versus PathFile: a comparative study of preparation time and postoperative pain

Background

This randomized clinical trial aimed to compare the preparation time and severity of postoperative pain between HyFlex Electric Discharge Machine (EDM) glide path file (GPF) and PathFile.

Methods

Eighty patients whose molar teeth had at least one severely curved canal were treated by the same specialist. After access cavity preparation, the patients were randomly assigned to receive glide path enlargement with either HyFlex EDM GPF or PathFile. ProTaper Next X1 and X2 files were used to prepare the canals. The time of preparation was assessed and the severity of postoperative pain over the next 7 days was recorded. The preparation time and the postoperative pain scores were compared using the Linear Mixed Models (P ≤ 0.05).

Results

Glide path enlargement time was significantly shorter with HyFlex EDM GPF (27.828 ± 2.345 s) than with PathFile (48.942 ± 2.864 s) (P < 0.001). The highest postoperative pain score was recorded on the first day and the pain decreased over time in both groups. HyFlex EDM GPF group patients reported significantly less postoperative pain than PathFile group patients overall (P < 0.001).

Conclusions

Postoperative pain and glide path preparation time could be reduced by using HyFlex EDM GPF system.

Trial registration PKUSSNCT, PKUSSNCT-17B12, Registered 24 October 2017.

Root canal shaping of curved canals by Reciproc Blue system and Pro Taper Gold: A micro-computed tomographic study

Background

This study aimed to evaluate the centralization and transportation of ProTaper Gold (PTG) rotary system and Reciproc Blue (RB) reciprocating system in curved canals, by using micro-CT.

Material and Methods

Twenty extracted mandibular molars were previously scanned by using the SkyScan 1174 microtomograph to select the Vertucci IV anatomic type. The specimens were divided into two groups (n=10) according to the mechanized system used to prepare the root canals. The teeth were scanned by micro-CT to calculate the increase volume, percentage of dentin removed, remaining dentin thickness, structure model index (SMI), degree of transportation and centering ability of root canals. The Student's t test was used to evaluate differences between PTG and RB in each measurement evaluated.

Results

No significant differences were found between the groups in the increase of the total root canal and apical volume; percentage of dentin removed after preparation; SMI of the mesiolingual canal; degree of transportation of the canal and centering ability of the cervical and middle thirds (P>0.05). There were significant differences in the mesiobuccal canal in SMI and in the centering ability of the apical third (P<0.05). Concerning the remaining dentin thickness, there was also no significant diferences between the groups, except for some regions were RB was observed to have a superior cutting capacity (P<0.05).

Conclusions

Both systems were efficient and safe for performing preparation of the moderately curved root canals of mandibular molars. RB instruments produced more circular and better centralized canals in the apical third of the mesiobuccal canal, with superior cutting action when compared with PTG instruments. Key words:Nickel-titanium instrument, heat treatment, micro-computed tomography, canal transportation.

Comparison of Canal Transportation and Centering Ability of ProGlider and WaveOne Gold Glider in Curved Canals

OBJECTIVES

 The aim of this study was to compare the volume variation and maintenance of the root canal position when using the ProGlider 16.02 (PG) and the WaveOne Gold Glider 15.02 (WOGG) file systems for glide path preparation.

MATERIALS AND METHODS

 Twenty-four moderately curved mesiobuccal canals of maxil-lary first molars were selected and randomly divided into two groups: PG and WOGG. The selected teeth were scanned using microtomography before and after root canal preparation to assess centralization and linear transport at 1, 3, 5, and 7 mm from the apical foramen.

STATISTICAL ANALYSIS

 The data were analyzed with the Mann-Whitney U test. The level of significance was 5%.

RESULTS

 There were no significant differences in volume variation or root canal transport (p > 0.05). There was a significant difference in the centralization of the root canal at 3 mm from the foramen (p < 0.05).

CONCLUSIONS

 WOGG and PG instruments presented similar results regarding the root canal volume increase and transport. WOGG caused higher decentralization at 3 mm from the apical foramen.

Influence of Negotiation, Glide Path, and Preflaring Procedures on Root Canal Shaping-Terminology, Basic Concepts, and a Systematic Review

INTRODUCTION

Negotiation, glide path, and preflaring are essential steps in root canal shaping procedures. This report aimed to discuss the terminology, basic concepts, and clinical considerations of negotiation, glide path, and preflaring procedures and the influence of these steps on root canal shaping.

METHODS

This systematic review was undertaken following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The protocol has been registered with the International Prospective Register of Systematic Reviews (number CRD42019127021). A comprehensive literature search was performed by 2 independent reviewers using a selected search strategy in 2 electronic databases (PubMed and Scopus) until January 28, 2019. A further search was performed manually in endodontic journals. Studies investigating or comparing at least 1 shaping property resulting from root canal instrumentation with a glide path or preflaring in human extracted teeth or clinical studies were included.

RESULTS

The literature shows that the definition of glide path and preflaring procedures remains controversial, which requires an elaboration in the American Association of Endodontists' Glossary of Endodontic Terms. After the removal of irrelevant and duplicated articles, 98 articles were included. The impact of glide path preparation and preflaring on working length determination, apical file size determination, canal transportation, separation of endodontic files, shaping time, dentinal microcrack formation, and extrusion of debris was discussed. Because of heterogeneity among the included studies, quantitative synthesis was not performed for most of the parameters.

CONCLUSIONS

An evidence-based guideline is needed to define and correlate the basic concepts and current applications of each step of contemporary advancements in root canal instruments. Glide path preparation reduces the risk of debris extrusion, has no influence on the incidence of dentinal crack formation, and improves the preservation of the original canal anatomy. The creation of a glide path may have no impact on Reciproc files (VDW, Munich, Germany) in reaching the full working length. Preflaring increases the accuracy of working length determination. Further randomized clinical trials are required to evaluate the effect of a glide path and preflaring on root canal treatment outcomes.

Residual smear layer after root canal instrumentation by using Niti, M-Wire and CM-Wire instruments: A scanning electron microscopy analysis

Objective:

The purpose of this study was to compare the amount of residual smear layer after root canal instrumentation by using Ni-Ti, M-Wire, and CM-Wire instruments.

Materials and Methods:

Seventy-two mandibular incisors were randomly divided into six groups according to the system used: WaveOne (WO), Reciproc (RP), Unicone (UC), ProTaper Next (PN), Mtwo (MT), and HyFlex (HF). Afterward, the specimens were cleaved in the mesiodistal and buccolingual direction for analysis by scanning electron microscopy.

Results:

Considering both directions and root canal thirds, there was no difference between HF, MT, and PN. RP, UC, and WO presented a significant difference between the directions, and the cervical third showed a significantly smaller quantity of residual smear layer compared with the apical third. When the systems were compared among them, there was a significant difference only between RP and WO.

Conclusions:

Residual smear layer observed after instrumentation with the different systems was similar, except for quantities between the reciprocating systems.

Micro-Computed Tomography (Micro-CT) Evaluation of Effects of Different Rotary Glide Path Techniques on Canal Transportation and Centering in Curved Root Canals

BACKGROUND The aim of this study was to evaluate the ability of different rotary glide path techniques to maintain canal anatomy by comparing canal transportation and centring abilities in curved root canals using X-ray micro-computed tomography (micro-CT). MATERIAL AND METHODS We selected 36 root canals and randomly assigned them to 3 groups. The first group was instrumented using Pathfile (PF) 1 and PF2, the second group using PF2, and the third group using a Proglider (PG) instrument. Selected tooth samples were scanned using a micro-CT system with 8-µm resolution. Centring ability and transportation were compared at 5 levels: 0.5 mm (A0) and 1 mm (A1) from apical foramen, at the point of maximum root curvature (C0), at 1 mm below it (C-), and 1 mm above it (C+). Area, ratio of areas (RA), perimeter, centroid shift, mean diameter, and ratio of diameter ratios (RDR) were assessed. RESULTS In all groups, there were no significant differences between different levels in all parameters (p>0.05). In group 1, the centroid shift was greatest at A0 and C-, and the least impact was at C0. In group 2, the biggest impacts were at C- and A0, and the smallest at C+. In group 3, the greatest impacts were at A0 and A1, and the smallest at C0. CONCLUSIONS All 3 instrument groups performed very similarly, without significant differences in canal-shaping parameters. Overall, using just PF2 instead of PF 1 and 2 created very similar shaping results, which could reduce the number of instruments needed and the cost of treatment.

Root Canal Shaping Using Nickel Titanium, M-Wire, and Gold Wire: A Micro-computed Tomographic Comparative Study of One Shape, ProTaper Next, and WaveOne Gold Instruments in Maxillary First Molars

INTRODUCTION

The aim of this study was to evaluate the root canal shaping effect of instruments manufactured from nickel titanium, M-Wire, and Gold wire with different glide path preparation techniques.

METHODS

One hundred thirty-five mesiobuccal canals of extracted human maxillary molars were randomly divided into 3 equal groups (N = 45) for glide path preparation with K-files (KF) (Dentsply Sirona, Ballaigues, Switzerland), One G (OG) files (Micro-Mega, Besançon, France), and ProGlider (PG) files (Dentsply Sirona). Specimens of each glide path group were further divided equally into 3 groups for instrumentation with ProTaper Next (PTN, Dentsply Sirona), One Shape (OS, Micro-Mega), and WaveOne Gold (WOG, Dentsply Sirona) systems (n = 15). Micro-computed tomographic imaging was used to scan teeth before instrumentation and after shaping to compare centering ratio and canal transportation values at the apical, midroot, and coronal levels and the overall changes in canal volume. Data sets were statistically analyzed (analysis of variance and Kruskal-Wallis H tests).

RESULTS

The centering ratios for all groups were statistically similar at all levels. Apical canal transportation was significantly high for K/OS and K/PTN (P = .003). Midroot canal transportation was significantly high for K/PTN, K/OS, and OG/OS (P = .0003). Coronal canal transportation was significantly high for K/PTN and K/OS (P = .011). The highest change in canal volume was observed with all PTN groups and the lowest with PG/WOG (P = .06).

CONCLUSIONS

WOG manufactured from Gold wire combined with PG showed better root canal shaping ability and removed less dentin from the canal walls. The nickel-titanium (OS) and M-Wire (PTN) instruments used in combination with KF significantly transported more canals. PTN removed the most dentin from the canal walls regardless of the GPP technique.

Comparison of glide paths created with K-files, PathFiles, and the ProGlider file, and their effects on subsequent WaveOne preparation in curved canals

BACKGROUND

The root canal glide path has been recommended as the foundation for a safer root canal preparation. The aim of this study was to compare glide paths created with K-files, PathFiles, and the ProGlider file, and their effects on subsequent WaveOne preparation regarding canal transportation, canal volume increase, apical extruded debris, and working time in curved canals.

METHODS

Sixty mesial canals of extracted human mandibular first molars were randomly assigned to the K-file (KF), PathFile (PF) and ProGlider file (PG) groups for glide path preparation. Then, canals were prepared using WaveOne files. Specimens were scanned (voxel size: 18 μm) three times using micro-computed tomography: pre-glide path, post-glide path, and post-root canal preparation. Canal transportations were measured at 1, 3, and 5 mm levels from the apical foramen, and canal volume increases were also accounted. Apical extruded debris during preparation was collected for measurement. Meanwhile,working time was recorded. Data were analyzed statistically using one-way analysis of variance and Tukey's post hoc tests (p < 0.05).

RESULTS

After glide path preparation, the PG and PF groups showed significantly less canal transportation than the KF group at all levels (P < 0.05), while the PG group exhibited a significantly larger canal volume increase than the PF and KF groups (P < 0.05). After the subsequent canal preparation with WaveOne, the PG and PF groups showed significantly less canal transportation than the KF group at 3 and 5 mm levels, and the PG group showed significantly less canal transportation than the PF group at 5 mm level (P < 0.05). However, statistically similar canal volume increases occurred among the three groups. Additionally, the PG and PF groups produced less apical extruded debris compared to the KF group (P < 0.05). The working time of the PG group was the shortest, while that of the KF group was the longest.

CONCLUSION

Compared with the PathFiles and K-files, the ProGlider file combined with the WaveOne file showed reduced canal transportation and working time.

Comparison of PathFile and ProFinder Systems to Create a Glide Path in Curved Root Canals

Objective:

Root canal shaping is as important as irrigation and filling when attempting to obtain a high success rate in endodontic treatment. The creation of a glide path before the use of rotary instruments reduces the risk of posterior iatrogenic errors. The objective of the present study was to evaluate instrumentation time and root canal transport after using 2 different glide path rotary systems.

Methods:

In total, 60 mesiobuccal root canals of mandibular molars, with curvature angles between 11° and 82°, were standardized to measure 15 mm. The specimens were divided into 2 groups, depending on their angles of curvature (11º–38º and 39º–82º), and further divided into 4 groups (n=15). Two groups were instrumented using the PathFile system and the other 2 using the ProFinder system. The angle and radius of curvature were measured at the most abrupt angle of curvature before and after instrumentation. Both measurements were analyzed and compared using AutoCAD software to determine canal transportation. Curvature angles were compared using Student’s t test and the radii of curvature using the Wilcoxon test. The time for instrumentation was also evaluated using Student’s t tests.

Results:

There were no statistically significant differences between the two systems with respect to root canal transport (P>0.05); however, the ProFinder system took a longer time to create a glide path (P=0.004).

Conclusion:

Both systems were equally effective in creating a glide path; however, the PathFile system proved to be faster than the ProFinder 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.

Glide Path Enlargement of Mandibular Molar Canals by Using K-files, the ProGlider File, and G-Files: A Comparative Study of the Preparation Times

INTRODUCTION

The preparation of a glide path before the introduction of rotary nickel-titanium instruments is a standard adjunct to ensure increased safety during root canal preparation. The aim of this study was to compare the mean preparation time of manual instrumentation with K-files, G-Files, and the ProGlider instrument to prepare a glide path in curved root canals.

METHODS

The mesial canals of 90 mandibular molars (with curvature angles between 25° and 35°) were selected. The specimens were randomly divided into 3 groups with 30 canals each, and canal preparations were performed by an endodontist who used #10-15-20 stainless steel manual K-files (group KF), #10 stainless steel manual K-file followed by #12-17 G-File instruments (group GF), and #10 stainless steel manual K-file followed by #16 ProGlider instrument (group PG). The total time it took to prepare the glide paths was recorded with an electronic stopwatch. New instruments were used for each canal.

RESULTS

Glide path enlargement with the PG group (27.9 ± 8.6 seconds) and GF group (41.9 ± 20.1 seconds) was shown to be statistically significantly faster than stainless steel KF group (74.9 ± 24.1 seconds) by using analysis of variance (P < .05). There was no statistically significant difference observed between the mean preparation times of the PG and GF groups (P < .05).

CONCLUSIONS

Glide path preparation times with the rotary instrument groups were significantly faster than with stainless steel manual K-files.

Micro-CT evaluation of several glide path techniques and ProTaper Next shaping outcomes in maxillary first molar curved canals

AIM

To evaluate the ability of ProGlider instruments, PathFiles and K-files to maintain canal anatomy during glide path preparation using X-ray computed micro-tomography (micro-CT).

METHODOLOGY

Forty-five extracted maxillary first permanent molars were selected. Mesio-buccal canals were randomly assigned (n = 15) to manual K-file, PathFile or ProGlider groups for glide path preparation. Irrigation was achieved with 5% NaOCl and 10% EDTA. After glide path preparation, each canal was shaped with ProTaper Next X1 and X2 to working length. Specimens were scanned (isotropic voxel size 9.1 μm) for matching volumes and surface areas and post-treatment analyses. Canal volume, surface area, centroid shift, canal geometry variation through ratio of diameter ratios and ratio of cross-sectional areas were assessed in the apical and coronal levels and at the point of maximum canal curvature. One-way factorial anovas were used to evaluate the significance of instrument in the various canal regions.

RESULTS

Post-glide path analysis revealed that instrument factor was significant at the apical level for both the ratio of diameter ratios and the ratio of cross-sectional areas (P < 0.001), with an improved maintenance of root canal geometry by ProGlider and PathFile. At the coronal level and point of maximum canal curvature, ProGlider demonstrated a tendency to pre-flare the root canal compared with K-file and PathFile. PathFile and ProGlider demonstrated a significantly lower centroid shift compared with K-file at the apical level (P = 0.023). Post-shaping analysis demonstrated a more centred preparation of ProGlider, compared with PathFile and K-files, with no significant differences for other parameters.

CONCLUSIONS

Use of ProGlider instruments led to less canal transportation than PathFiles and K-files.

Influence of Cervical and Apical Enlargement Associated with the WaveOne System on the Transportation and Centralization of Endodontic Preparations

INTRODUCTION

The aim of this study was to evaluate through computed microtomography the transportation and centralization of root canals instrumented using the WaveOne system (Dentsply Maillefer, Ballaigues, Switzerland) associated or unassociated with previous apical and cervical enlargements.

METHODS

Thirty-six mandibular molars were selected with independent mesial roots and curvatures and randomized into the following groups: PathFile (Dentsply Maillefer) before WaveOne Primary (the PFWO group), ProTaper Universal SX (Dentsply Maillefer) before WaveOne Primary (the SXWO group), and WaveOne Primary (the WO group). Computed microtomographic imaging was performed pre- and postpreparation to obtain measurements of mesial and distal dentin walls and calculations of root canal transportation (%) and centralization. One-way analysis of variance was performed to compare the different groups, repeated measures analysis of variance for comparison of the root thirds in each group, and the Student t test for comparisons between the mesiobuccal and mesiolingual canals.

RESULTS

Transportation of the cervical and middle thirds to the danger zone was observed in both roots, whereas the apical thirds were transported to the outer face of the curvature. In the PFWO and SXWO groups, less transportation was observed in the middle thirds of the mesiobuccal canals compared with the WO group (P < .05). Centralization remained almost unchanged in the SXWO group (P < .05).

CONCLUSIONS

In each group, transportation toward the danger zone was mostly observed in the cervical thirds of the mesiobuccal canals. Cervical or apical enlargement resulted in reduced transportation and improved centralization of the middle thirds compared with the exclusive use of the WaveOne system.