Canal Straightening Research Articles

PENGEMBANGAN INOVASI PRODUK KOMPOSIT MODUL SEKAT KANAL BERBAHAN BAKU SERAT SABUT KELAPA UNTUK PENERAPAN PENYEKATAN KANAL PADA LAHAN GAMBUT

Peatlands in West Kalimantan, Indonesia, are an important ecosystem but are vulnerable to degradation caused by human activities. To overcome this problem, this research introduces a product innovation in the form of a canal-blocking module made from coconut fiber composite for the implementation of sustainable canal straightening. The study involved a series of methodological steps that included a literature study, prototype development, laboratory testing, and field case studies. The research results show that composite canal-blocking modules have significant potential to reduce land subsidence, increase land productivity, and improve the hydrological balance in peatlands. In addition to significant economic benefits for local communities, implementation of this module also has positive impacts on the environment, including habitat protection and reduced greenhouse gas emissions. These findings have important implications for policy-making and planning for peatland management in West Kalimantan, emphasizing the importance of sustainable solutions and community participation in overcoming the challenges faced by this ecosystem. This research highlights the potential for innovative canal block module composite products made from coconut fiber as an important step in efforts to strengthen peatland management in West Kalimantan. The next step is to encourage wider adoption and implementation of these solutions while pursuing further research to deepen our understanding of sustainable peatland management.

Micro-computed tomographic evaluation of the shaping ability of three nickel-titanium rotary systems in the middle mesial canal of mandibular first molars: an ex vivo study based on 3D printed tooth replicas

BackgroundThe preparation of the middle mesial (MM) canal of mandibular molars represents a challenge because it is often curved, narrow, and close to the root concave. The purpose of this study was to evaluate the ex vivo shaping ability of 3 nickel-titanium (NiTi) rotary systems in the MM canal using 3D printed resin tooth replicas.MethodsA permanent mandibular first molar with a MM canal was acquired from a pool of extracted teeth and reproduced by a 3D printer. The resin tooth replicas (n = 18) were equally assigned to 3 groups for the evaluation of the shaping abilities of 3 NiTi rotary systems (OneShape [OS], Twisted Files [TF], and ProTaper Gold [PTG]) according to the manufacturer’s recommendations. The tooth replicas were scanned by micro-computed tomography (micro-CT) twice before and after instrumentation of the mesiobuccal (MB), mesiolingual (ML), and MM root canals. After 3D reconstruction, the canal straightening, change of root canal volume and surface area, the mesial and distal canal wall thickness and canal transportation at the levels of 1, 2, and 3 mm below furcation were assessed. One-way variance analysis and Turkey’s post hoc test were used for comparisons of the means among different groups, and paired-t test was used to compare the mesial and distal sides of the mesial roots.ResultsAs compared with OS and TF, the use of PTG in preparation of MM canals resulted in significantly more straightening of canal curvature (p < 0.05), greater post-instrumentation canal volume and surface area, and thinner mesial and distal remaining canal wall thickness at 1, 2 and 3 mm below furcation (all p < 0.05). Regarding the root canal transportation in the mesiodistal direction, there was no significant difference among the 3 instruments (all p > 0.05) after the preparation of the MB and ML canals. However, in the MM canal, more pronounced transportation was detected in the PTG group at 2 mm below furcation, and in the TF group at 3 mm below furcation as compared with the other 2 systems (both p < 0.05).Conclusions3D printed tooth replicas have the advantages of consistency and can be an ideal model to evaluate the shaping ability of different instruments in the MM canal. OS and TF files performed similarly and both are appropriate for shaping the MM canal, while PTG may cause excessive and uneven resin removal, especially near the furcation, and may lead to root fragility and procedural errors.

Teaching rotary root canal instrumentation using a Peyton teaching approach.

The aim of the study was two evaluate the effectiveness of a Peyton teaching approach for rotary root canal instrumentation, in comparison to the traditional "see one-do one" method. Forty undergraduate students were randomly divided into two groups (n=20). Students of the first group (G1) were taught how to use rotary instrumentation using a modified Peyton method, whilst the second group (G2) watched a teaching video (30 min) on the same subject. Both groups instrumented a plastic block and subsequently both mesial canals of an extracted lower molar. The quality of the root canal instrumentation was analysed by 2 blinded observers on video recordings and x-rays. Interobserver correlation was 0.917 (p < .0005; Pearson) for the assessment of the video recordings; students of G1 received significantly more total points (83.55 ± 6.82 points) compared to G2 (69.76 ± 13.82) (p=.001; t-test), the gender had no significant effect on the overall results (p=.444; two-way ANOVA). Significant differences were detected for the categories "initial scouting," "coronal enlargement," "glide path preparation," "preparation using X2 file," "preparation using X3 file" (p < .05; t-test) as well as for the subcategories "sequence of rinse, recapitulation, rinse" (p=.001; t-test) and "recapitulation" (p < .002; t-test). No differences between groups were observed for the radiographic evaluation with respect to working length and canal straightening. Teaching rotary instrumentation by using the Peyton approach resulted in improved performance of undergraduate students assessed with a checklist-based process analysis. Enhanced implementation of rotary instrumentation could result in better long-term results of students' root canal treatment.

Shaping ability of rotary and reciprocating single-file systems in combination with and without different glide path techniques in simulated curved canals

Background/purposeGlide path management (GPM) is a consequential clinical step that serves to influence predictably successful root canal therapy. However, the effect of GPM on the shaping ability of single-file system remains controversial. This study compared the performance of rotary single-file One Curve (OC) and reciprocating single-file Reciproc Blue (RCB) in combination with/without different glide path techniques: no glide path preparation (NG), PathFile (PF), ProGlider (PG) and WaveOne Gold Glider (WOGG), respectively. Materials and methods80 simulated curved canals (n = 10 canals/per group) were instrumented to an apical size of 0.25 mm using OC and RCB in combination with/without different glide path techniques, respectively. The amount of resin removal, canal transportation, and the degree of canal straightening were measured in Photoshop CS6 software. Statistical analysis of the data was performed by using Kruskal–Wallis test, followed by Dunn's post hoc test with Bonferroni correction (α = 0.05). ResultsPost–glide path analysis found that WOGG and PG produced less canal transportation and curvature straightening than PF (P < 0.05). Post-shaping analysis showed that OC groups removed significantly less resin than RCB groups (P < 0.05). The PG and WOGG subgroups in both OC groups and RCB groups produced less transportation and curvature straightening than NG and PF subgroups (P < 0.05). OC + PG subgroup and OC + WOGG subgroup yielded the least canal transportation and curvature straightening (P < 0.05). ConclusionPG and WOGG can improve the shaping ability of OC and RCB instrument. OC, especially when combined with PG and WOGG, has a less aggressive dentin cutting and more centered preparation than the RCB instrument.

T-Endo MUST ve WaveOne Gold'un Rehber Yol Eğeleri ile Şekillendirme Yeteneklerinin Karşılaştırılması: İn Vitro Çalışma

Objective: The aim was to compare the shaping ability and the canal straightening of T-Endo MUST and WaveOne Gold reciprocal file systems with glide path files in resin J-shaped root canals. Material and Methods: Two groups (n=17) were established. TEM tg (13/.04) + TEM M25 (25/.06) and WOG Glider (15/.02) + WOG Primary (25/.07) were used to prepare the resin simulated canals. A series of preoperative and postoperative images were taken by a digital camera and they were superimposed. The curvature angles and the amount of resin removed from both the inner and the outer wall of the canal into the level of 7 mm from the apical point, with a 1 mm increment were measured. The data were evaluated with independent samples Student's t-test with 5% significance interval. Results: There was no statistically difference between TEM and WOG reciprocal files (p>0.05). No instrument fracture or canal aberrations were inspected during canal preparation. Conclusion: Within the limitation of this present study, TEM and WOG files maintained the original canal curvature in curved canals. They produced conservative shapes with lower foramen transportation.

Shaping ability of ProTaper Gold and WaveOne Gold nickel-titanium rotary instruments in simulated S-shaped root canals

Background/purposeGold metal technology improves flexibility and the resistance to cyclic fatigue of the endodontic mechanical files. This study compared the performance of ProTaper Gold (PTG) multiple file system and WaveOne Gold (WOG) single file system in simulated S-shaped root canals, which represents one of the most challenging root canal morphology. Materials and methodsForty S-shaped canals (n = 20 canals/per group) in resin blocks were instrumented to an apical size of 0.25 mm using PTG and WOG Primary, respectively. The total amount of resin removal, canal transportation, centering ratio, and the degree of canal straightening were measured in Photoshop CS6 software. Statistical analysis was performed by using Mann–Whitney U-test (α = .05). ResultsNone of the files fractured during the instrumentation. The WOG group removed significantly less amount of resin at 0, 3, 6, 7 and 9 mm from the apex (P < .05). The WOG group remained more centered in canals at 0 mm from the apex (P < .05). The PTG group showed a better centering ability and less canal transportation at 4, 5 and 6 mm from the apex (P < .05). In the coronal curvature portion, the use of WOG Primary significantly decreased curvature angle and increased radius compared with PTG instruments (P < .05). There was no significant difference between the two groups in terms of the apical curvature angle and radius change (P > .05). ConclusionThe WOG Primary file has a less aggressive dentin cutting and more centered apical preparation. The PTG system is more advantageous in shaping the coronal curvature of S-shaped canal.

Evaluation of the Shaping Ability of Three Thermally Treated Nickel–Titanium Endodontic Instruments on Standardized 3D-printed Dental Replicas Using Cone-Beam Computed Tomography

Background and Objectives: The aim of the present study is to compare the efficacy of three root canal preparation systems in the shaping of 3D-printed root canal replicas of single rooted teeth. Materials and Methods: Sixty 3D-printed root canal replicas were produced and divided into three groups, each consisting of twenty samples. Each group was shaped with a different instrument: Reciproc Blue R25/08 (VDW GmbH, Munich, Gemany), WaveOne Gold Primary 25/07 (Dentsply Sirona, Ballaigues, Switzerland), and ProTaper Gold F2 25/08 (Denstply Sirona). To ensure the reproducibility of pre- and post-operative CBCT images of the root canals, the endodontic printed replicas were placed in a mould of silicon impression material. A cone-beam computed tomography (CBCT) software was used to compare pre- and post-instrumentation images collected at three levels of the root canal length: 3, 6, and 9 mm from the apical foramen. The amount of transportation, centring ability, and curvature angle after shaping were evaluated for each system. The results were statistically analysed and compared using one-way analysis of variance (ANOVA). Results: Regarding the transportation of the root canal after shaping, significant differences between groups at 3 mm (p = 0.010721) and 6 mm (p = 0.000046) were recorded in the mesio-distal direction, while in the bucco-lingual significant differences were only observed at 6 mm (p = 0.000554). Reciproc Blue removed more dentin from the mesial and buccal wall of the root canal. When evaluating the centring ability of the three systems, significant differences were observed between the groups at the level of 9 mm (p = 0.037258) in the mesio-distal direction, and at the level of 6 mm (p = 0.038197) in the bucco-lingual direction. Significant differences of the canal curvature angle after shaping were also observed between groups (p = 0.000001). Reciproc Blue straightened the curvature the most, while ProTaper Gold the least. Conclusions: All systems produced minor root canal transportation. No instrument was able to achieve a perfect centring preparation of the root canal. All systems produced a small degree of root canal straightening.

Shaping Ability of Reciprocating Single-file Systems in Simulated Canals: Reciproc versus Reciproc Blue

The aim was to compare the canal straightening of M-wire [Reciproc (VDW, Munich, Germany)] and blue-wire heat-treated [Reciproc Blue (VDW) instruments in simulated resin L-shaped curved root canals. A total of 26 simulated L-shaped root canals with curvature of 45° and length of 17 mm (#15-0.02 taper) endo training blocks were divided into two groups (n = 13). All canals were prepared to an apical size 25 according to the manufacturers’ instructions. Pre- and post-instrumentation digital photography were superimposed and canal straightening was analysed using a computer imaging programme. Shapiro-Wilk test was used to determine the normal distribution of the data. For comparing two groups according to canal straightening independent t-test was used. During preparation no instrument fractured. All instruments maintained the original canal curvature well with no significant differences between the instruments. Regarding preparation time, no significant differences between the two instruments were obtained (P &gt; 0.05). Under the conditions of this study, instruments were safe to use and all instruments respected the original canal curvature well. It was concluded that reciprocal motion files with or without blue-heat treated had similar preparation time and similar shaping abilities at intracanal temperature and maintained root canal curves equally well.

Shaping Ability and Debris Extrusion of New Rotary Nickel-Titanium Root Canal Instruments.

The aim was to evaluate the canal straightening and the amount of apically extruded debris associated with five rotary nickel-titanium when preparing curved root canals. A total of 100 root canals in extracted human teeth (angles of curvatures 20°–30°; radii 5.9–13.5 mm) were divided into five groups (n = 20/group). The groups were balanced with respect to the angle and the radius of canal curvature. The root canals were prepared using conventional austenite 55-NiTi alloy instruments F360, F6 SkyTaper (both Komet, Lemgo, Germany), and the heat-treated NiTi Jizai, Silk-Complex and Silk-Standard instruments (all Mani, Tochigi, Japan) to an apical size 25. The amount of extruded debris was assessed with a micro balance. Statistical analysis was performed using Kruskal–Wallis test with Bonferroni correction at a significance level of p < 0.05. During canal preparation, neither instrument fractures nor procedural preparation errors were noticed. Regarding canal straightening, the use of Jizai instruments resulted in the significantly lowest straightening (p < 0.05), while no significant differences were obtained between all other groups (p > 0.05). Regarding the amount of apically extruded debris, no significant differences between all groups were obtained (p > 0.05). Within the limitations of this study, all instruments performed well, and especially the Jizai instruments showed an excellent shaping ability.

A Comparative evaluation of the shaping ability, canal straightening, and preparation time of five different NiTi rotary files in simulated canals

Aim:The aim is to compare the shaping ability, canal straightening, and the preparation time of five different nickel-titanium rotary files in simulated J-shaped canals.Materials and Methods:Ninety J-shaped canals in resin blocks were filled with 2% Methylene Blue solution and pre-instrumentation images were taken using a Leica microscope at a ×10. They were prepared until size 25 taper 0.04 using (n = 18 per group): T-Flex, HyFlex CM, Vortex Blue, S5, and iRace. After instrumentation, images were captured again, and composite images were made using Adobe Photoshop imaging software. The differences in canal width and canal curvature at each respective landmark were measured and compared. The preparation time and canal abbreviations were also recorded. Statistical analyses were performed using one-way ANOVA and post hoc Tukey HSD tests. The level of statistical significance was set to P = 0.05.Results:HyFlex CM demonstrated the least difference in canal width after instrumentation, but no significant difference (P > 0.05) as compared to T-Flex and Vortex Blue. The mean canal straightening ranged between 0.91° and 7.65°. T-Flex created the least canal straightening after instrumentation which was significantly less (P < 0.05) than S5, but there was no significant difference (P > 0.05) when compared to HyFlex CM. Instrumentation with the S5 file was significantly faster (P < 0.05), whereas HyFlex CM was the slowest.Conclusion:T-Flex, HyFlex CM, and Vortex Blue demonstrated better shaping ability, whilst T-Flex and HyFlex CM maintained the original canal curvatures well. S5 tended to straighten the canals and caused the greatest canal transportation, but it required the least amount of time to shape the canal.

A comparative evaluation of the shaping ability of four different single-file systems in severely curved mesiobuccal root canals of mandibular first molars: An in vitro study

Aim: The aim of this study was to compare the shaping ability of four different single-file systems in severely curved mesiobuccal root canals in extracted human mandibular first molars.Materials and Methods: Sixty extracted intact human mandibular first molars with at least one curved mesial root were collected and used for the study. The study samples (n = 60) were divided into four experimental groups (n = 15 each): WaveOne (WO) (Group I), WaveOne Gold (WOG) (Group II), OneShape (Group III), and F360 (Group IV). The working length was established. All the study samples were prepared with respective file systems according to manufacturer's instructions. Pre- and postinstrumentation radiographs were taken and images were transferred to AutoCAD 2016 to determine the radius of curvature of each root canal. The canal curvature was assessed as a difference between before and after instrumentation to determine canal straightening. The data obtained were subjected to statistical analysis using SPSS version 20.0.Results: The pre- and postinstrumentation readings were compared using one-sample t-test, and difference was found to be statistically significant (P < 0.05). The mean difference in root curvature was estimated by pre- and postinstrumentation readings. According to mean change in the root curvature, the order determined was Group IV < III < II < I. Intergroup comparison was conducted using ANOVA statistical analysis, and it was found to be statistically significant.Conclusion: WOG and WO reciprocating files showed a marked tendency to straighten the severely curved canals, whereas F360 and OneShape continuous files maintained the original canal curvatures well.

Shaping Ability of ProTaper Universal, ProTaper NEXT and WaveOne Primary in Severely Curved Resin Blocks

Complex anatomy of roots requires endodontic rotary instruments that respect and follow that anatomy. The purpose of this study was to compare the shaping ability of three engine-driven nickel-titanium instruments in severely curved simulated canals. Forty-eight severely curved simulated canals in resin blocks were prepared to an apical size of 25 using the following systems (n = 16 per group): ProTaper Universal (PTU), ProTaper NEXT (PTN), and WaveOne Primary (WO) (all Dentsply Maillefer, Ballaigues, Switzerland). Composite images were made from the superimposition of pre- and post-instrumentation images. The amount of resin removed by each system was measured by using a digital template and image analysis software. Shaping ability of each system was compared using different parameters: total resin removal, centering ability, canal transportation in the apical, middle and coronal third of canal. Preparation times were also recorded. The data were statistically analyzed by using analysis of variance, paired t-test, and Tukey's post hoc test. Canals prepared with PTN were better centered in the apical part than those prepared with WO and PTU (p < 0.05). WO removed significantly more resin at the outer aspect of the maximum point of curvature. WO and PTU caused similar canal transportations at 7 points out of 11 measuring points. At measuring points 3, 4, and 5 WO caused more canal straightening than PTU. Instrumentation with PTU required more time than with the two other instruments (p <0.05). No preparation error or instrument separation occurred. In the apical part of the canals PTN obtained the best results with regard to canal transportation. All of the rotary instruments were safe in preparing severely curved canals and PTN showed better preparation of apical part of the canal.

Assessment of shaping ability of rotary and reciprocating file systems using cone-beam computed tomography in mandibular molars: An in vitro study

Aim: The purpose of this study was to compare the canal transportation, centering ability, canal curvature, dentin removal, the volume of the curved root canals, and time taken during and after instrumentation with Wave One, Reciproc, F360, and One shape (OS) by using cone-beam computed tomography (CBCT). Materials and Methods: According to the file systems used for canal preparation, eighty mesiobuccal canals of mandibular molars were distributed into four groups (20 samples each): OS (Group 1), F360 (Group 2), Wave One (Group 3), and reciproc (Group 4). According to the manufacturer's instructions, all groups were prepared until size 25 taper. Canals were scanned using CS three-dimensional CBCT scanner (Carestream) before and after preparation at 2 mm, 5 mm, and 8 mm from the apex. The data collected were evaluated using SPSS software with ANOVA and post hoc for a significant difference. Results: Significant difference was found between the entire group at 2 mm and 5 mm (P = 0.021) and at 8 mm (P = 0.037), where F360 showed the least canal transportation. The mean values for centering ability were not found significant at 2 mm and 5 mm. OS proved to remain more centered than the other groups. Curved canals were instrumented better with minor canal straightening by using Reciproc. The dentin was removed more by using Wave One, whereas least dentin was removed by F360. During pre- and post-instrumentation scans the change in volume of the root canal were not found statistically significant. Wave One showed the maximum increase in the volume of the canal after instrumentation. For the preparation of the canal, the time taken was less with reciproc as compared to other groups. Conclusion: Therefore, according to the study single-file rotary instrument like F360 used in the continuous rotation is suitable instrument for the root canal preparation followed by Reciproc, OS, and Wave One.

Canal Straightening Following Overinstrumentation with Three Nickel-Titanium Rotary Instruments.

Aim:The aim of the present in vitro study to compare canal straightening following shaping of curved canals with three types of new generation nickel-titanium (NiTi) rotary instruments-ProTaper Next (PTN)®, BT RaCe (BTR)®, and WaveOne Gold (WOG)®- and three different levels of protrusion beyond the major apical foramen.Materials and Methods:Forty-five extracted human maxillary and mandibular molars with at least one curved canal were distributed in three comparable groups of 15 canals each. The canals were instrumented to the major foramen and then overinstrumented with the final file 0.5 mm, 1 mm, and 1.5 mm beyond the foramen using PTN (Group PTN = 15), BTR (Group BTR = 15), and WOG (Group WOG = 15). Standardized pre- and post-instrumentation radiographs of the root canal were obtained for all groups using digital intraoral radiographs coupled with software. Differences in the degree of curvature were regarded as straightening and canal curvature was evaluated based on Schneider technique using the AmScope software for measurements and compared between groups and levels of instrumentation applying Mixed-model ANOVA. Significance was set at 0.05.Results:Canal curvature tended to gradually straighten out as the level of instrumentation increased in all three groups without statistically significant difference among the groups (P = 0.826).Conclusion:Overinstrumentation in curved canals resulted in straightening of the canal curvature.

Comparison of the shaping characteristics of Neolix and Protaper Universal systems in preparation of severely-curved simulated canals.

BackgroundThe aim of this in vitro study was to compare the shaping characteristics of two types of nickel-titanium endodontic file systems with regard to the following parameters: Canal straightening, Canal deviation and Instrumentation time.Material and MethodsFifty severely curved canals simulated in resin blocks were prepared to an apical size 25 using Protaper Universal orNeolix systems (n=25 canals/group). The angle of canal curvature was determined before and after instrumentation. Pre- and post-operative images were superimposed to determine any canal deviation. The instrumentation time was also recorded. The data were statistically analyzed by using independent sample t-test and the Mann-Whitney U-test.ResultsThere were no significant differences between the groups in terms of the change in canal angle (P > 0.05). The Neolix system produced less canal deviation at 7 of the 12 measuring points (p<0.05). The Neolix system also required less instrumentation time (p<0.05).ConclusionsBoth rotary systems were capable of maintaining the original curvature of the root canal; however, the Neolix system resulted in less canal deviation as well as shorter instrumentation time. Key words:Apical foramen,canal transportation, nickel-titanium instruments, Protaper Universal, root canal preparation.

A COMPARATIVE STUDY OF APICAL TRANSPORTATION AND STRAIGHTENING OF TWO ROTARY NICKEL-TITANIUM SYSTEMS WHEN USING FINAL APICAL BRUSHING

INTRODUCTION: Apical transportation results in an inadequately clean apical area and makes apical seal more difficult thus affecting the final outcome and may lead to failure. OBJECTIVES: The aim of this study was to compare between the effect of two rotary nickel titanium systems after using final apical strokes on canal transportation and apical straightening of the canal. MATERIALS AND METHODS: Sixty mesiobuccal canals of extracted mandibular first molars with root canal curvature angle (25 to 45 degree) were selected. Canals were divided into two groups (n=30). In group I canals were prepared with OneShape file, while in group II, canals were prepared with Revo-S system. Each group was then sub-divided into two sub-groups according to the motion used (pecking or circumferential filing). Sub group Ia (OneShape file) and sub group Ib (Revo-S system) were prepared with pecking motion while sub group II an and sub group II b were prepared with circumferential filing motion. A radiographic platform was used to obtain accurate radiographs. All specimens were radiographed from proximal and mesiodistal views. To measure apical transportation, the pre and post-instrumentation radiographs were exported from the Kodak software into Photoshop program. Then a grading system was used to assess the amount of transportation. Based on apical curvature measured before and after instrumentation (using Image J program), canal straightening was determined as the difference between these two measurements. RESULTS: Regarding apical transportation, no statistical significance was found between both groups and the sub groups. Apical straightening was evaluated, and no statistical significance was found between the groups. However, circumferential filing produced more straightening. CONCLUSIONS: OneShape file and Revo-S system maintained the original canal curvature with no significant differences between the files. Circumferential filing motion with both systems resulted in higher values of straightening when compared to pecking motion.

Shaping ability of single versus multi file rotary Ni-Ti systems in curved root canals

Objectives The aim of this study is to compare the shaping ability (straightening of curved root canals, apical transportation, preparation time) of single and multi-file rotary systems during the preparation of curved root canals in extracted human molar teeth. Methods Sixty mandibular molars were divided according to the instrument used into three groups of 20 teeth each: group PTU (ProTaper Uneiversal), group PTN (ProTaper Next) and group OS (One Shape). Using standardized pre- and post-instrumentation radiographs, straightening of canal curvature was determined using image analysis software. A double-digital standardized radiographic technique was used to determine apical transportation. Preparation time was also recorded. Data were analysed using one-way analysis of variance (ANOVA) and post hoc Tukey's test, and significance was set at P Results During root canal preparation, no instruments fractured. The use of PTN resulted in significantly less canal straightening followed by OS then PT. There were no significant differences between the three groups with respect to apical transportation. PTN were significantly faster than PTU and OS. Conclusion Under the conditions of this study, ProTaper Next Protaper Universal and One Shape instruments respected original canal curvature and were safe to use. Protaper Next was the fastest among them.

COMPARATIVE STUDY OF SHAPING ABILITY OF REVO-S AND ONE SHAPE NICKEL-TITANIUM ROTARY SYSTEMS IN CURVED ROOT CANALS. (AN IN VITRO STUDY)

Aim of the study: was to compare the shaping ability of One Shape, Revo-S NiTi rotary instruments, and stainless steel K-Flexofile instruments when used to prepare curved root canals. Methodology: A total of sixty mesiobuccal root canals of extracted human permanent mandibular molars were used. Those had curvature ranging between 200- 400, radius of curvature between 4-10 mm, and length of curved part between 6-8 mm. The samples were divided into three groups of 20 teeth each according to the instrument used. Using Digora system, the degree of straightening was calculated by comparing pre and post-instrumentation radiographs. Using cone beam computed tomography, mesial and distal dentin thicknesses were measured pre and post- instrumentation, and then applied in an equation given by Gambill et al., to calculate the centering ratio and transportation of the canals. Both rotary systems showed good centering ability and less canal straightening and transportation compared with stainless steel K-Flexofile, with no significant difference between the rotary systems. Results: Tukey’s pair-wise test showed that K-Flexofile showed the highest mean degree of straightening, degree and direction of canal transportation and the centering ability while One Shape had the lowest mean. No statistically significant difference was found between One Shape and Revo-S. Conclusion: Both rotary systems caused less transportation and remained better cantered in the canal than stainless steel K-Flexofile instruments, with no significant difference between One Shape and Revo-S.

Comparison of Hero 642 and K3 rotary nickel-titanium files in curved canals of molars and a systematic review of the literature.

The aim of the present study was to compare the root canal preparation ability of rotary nickel-titanium (NiTi) Hero 642 and K3 files in curved mandibular or maxillary molars. A total of 40 extracted mandibular molars with two separate mesial canals, an apical width of approximately size ≤15 and a root canal curvature of 15–30° were randomly divided into two groups and instrumented using Hero 642 (n=20) or K3 files (n=20). Canal straightening, working length, transportation, cross-sectional area, minimum dentin thickness and the canal angle curvature degree were examined, and a systematic review of the literature was conducted. No statistically significant differences were observed between the two groups with regard to the mean degree of straightening, mean change in working length, mean transportation, amount of dentin removed or remaining minimum dentin thickness (P>0.05). The canal angle curvature decreased in the two groups postoperatively. The systematic review identified six studies, and overall the two files performed similarly in the majority of categories examined. Therefore, the rotary NiTi Hero 642 and K3 files demonstrated comparable shaping abilities and maintenance of working length.

Comparative evaluation of the shaping ability of ProTaper Next, iRaCe and Hyflex CM rotary NiTi files in severely curved root canals

To compare the shaping ability of ProTaper Next, iRaCe and Hyflex CM rotary NiTi files during the preparation of severely curved root canals in extracted human molar teeth. Sixty mandibular molars with mesio-buccal canals having angles of curvature ranging from 25° to 35° were divided according to the instrument used into three groups of 20 teeth each: group PTN (ProTaper Next), group IR (iRaCe) and group HF (Hyflex CM). Using standardized pre- and post-instrumentation radiographs, straightening of canal curvature was determined using image analysis software. A double-digital standardized radiographic technique was used to determine apical transportation 0.5 mm from the working length (1.5-mm coronal of the major foramen). Preparation time and instrument failures were also recorded. Data were analysed using one-way analysis of variance (anova) and post hoc Tukey's test, and significance was set at P < 0.05. During root canal preparation, no instruments fractured. The use of PTN resulted in significantly greater canal straightening than IR and HF (P < 0.05), with no significant differences between IR and HF (P > 0.05). There were no significant differences between the three groups with respect to apical transportation (P > 0.05). IR and HF were significantly faster than PTN (P < 0.05), with no significant differences between IR and HF (P > 0.05). Under the conditions of this study, PTN, IR and HF respected original canal curvature well and were safe to use.