Rotary Technology Research Articles

Evaluation of Ozone Therapy in Endodontic Treatment of Teeth with Necrotic Pulp and Apical Periodontitis: A Randomized Clinical Trial

IntroductionThe aim of this study was to compare the effect of different application techniques of ozone on the prevalence of postendodontic pain in patients undergoing single-visit root canal treatment. Methodshundred eight patients with necrotic pulp in single-rooted teeth and apical periodontitis participated in the trial. A standard single-visit endodontics protocol was followed with 5.25% sodium hypochlorite and rotary nickel-titanium files. After shaping and cleaning, patients were randomly allocated into the following groups: group 1 (n = 21), ozone treatment with no activation (NA); group 2 (n = 22), ozone treatment with manual dynamic activation (MDA); group 3, (n = 21), ozone treatment with passive ultrasonic activation (PUA); group 4 (n = 23), ozone treatment with sonic activation (SA); and group 5 (n = 21), no ozone treatment (the control group). Patient levels of discomfort were recorded at 6 different time intervals using the visual analog scale (VAS). Comparison of the mean difference between the groups and time intervals was performed using 2-way analysis of variance followed by a post hoc Bonferroni test. The level of significance was set at 5%. ResultsVAS scores were highest for the control > NA > MDA > SA > PUA groups. A statistically significant reduction in VAS scores was observed in the PUA and SA groups in comparison with the NA, control, and MDA groups. Timewise comparison showed a highly significant decline in VAS scores at all time intervals (P < .001). ConclusionsUltrasonic and sonic activation of ozone resulted in less pain in patients undergoing single-visit endodontics compared with no ozone treatment.

Comparative evaluation of sterilization- and temperature-dependent cyclic fatigue resistance of four different nickel-titanium rotary file systems with reciprocal motion

Aim: The aim of this study was to examine the effect of sterilization and temperature differences on the cyclic fatigue resistance of WaveOne Gold, Reciproc, Reciproc Blue, and Twisted File Adaptive rotary file systems. Methods: In total, 160 files and four file systems were used (n = 20). This study was carried out at two different temperatures: 20°C and 39°C. An artificial stainless-steel canal was used for the static cyclic fatigue test. The breaking times of the files were recorded and calculated by multiplying the number of revolutions by the rotational speed. The SPSS 22 program was used for statistical analysis. The Shapiro–Wilk test was used for data with a normal distribution. The Mann–Whitney U test was used for paired groups. The Kruskal–Wallis test was applied to groups with more than two variables where the data did not fit a normal distribution. Tukey’s post-hoc analysis was used to determine the source of differences. A value of p&lt;0.05 was considered statistically significant. Results: When the lengths of the broken pieces and the numbers of breaks were compared at the two different temperatures, there was a significant difference between all the files. In addition, there was a significant between-group difference between the sterilized files and nonsterilized files (p &lt; 0.05). Conclusion: The cyclic fatigue resistance of the Reciproc Blue file was higher than that of the other files. Low temperature increased cyclic fatigue resistance. How to cite this article: Çelikel B, Öztekin F. Comparative evaluation of sterilization and temperature-dependent cyclic fatigue resistance of four different nickel-titanium rotary file systems with reciprocal movement. J Med Dent Invest 2021;2:e211038 https://doi.org/10.5577/jomdi.e211038 Linguistic revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English. Checked for plagiarism: Yes

Surface Defects of Used Reciproc and Reciproc Blue Rotary Nickel-Titanium Files (In Vitro Study)

Surface Defects of Used Reciproc and Reciproc Blue Rotary Nickel-Titanium Files (In Vitro Study)

A review on the effect of using rotary hyflex electrical discharge machining endodontic files on the formation of dentinal microcracks in straight root canals

Endodontic therapy is based on cleaning and shaping the canal system till the apex with total obturation of the canal. However, it is not always straightforward. Endodontics specialists face many complicated cases as sever curved canals, calcified canals and canals with previously initiated therapy which require to deal with. dental professionals pay attention to create new methods or to improve the already developed equipment and procedures to facilitate their work. Rotary endodontics files are in the center of attention. nowadays, recent files with extraordinary properties have been revolutionized. The standard Nickel Titanium rotary endodontic files are not always preferred. It cannot serve well in the aforementioned complex cases due to its larger tapers and unique shape memory property. Moreover, these files have led to several dentinal microcracks formation during canal preparation using the flaring instruments. Microcracks are evaluated through the accurately presented sliced images using Micro-Computer Tomography (micro-CT) done before and after root canal preparation. This has led to the invention of new generations of rotary endodontics files, with unique properties improving its behavior during the instrumentation, including Controlled Memory (CM) files and Electrical discharge Machine (EDM) files, opening the door for a new era in the field of endodontics dentistry. The present study aims to review HyFlex EDM files, including their properties, clinical dental usage, and the role of micro-CT in analyzing dentinal micro cracks formed with HyFlex EDM files.

Comparison of the effects from coronal pre-flaring and glide-path preparation on torque generation during root canal shaping procedure.

This study aimed to evaluate the effect of glide-path preparation and coronal pre-flaring on torque generation of rotary nickel-titanium files. Sixty mesiobuccal root canals of 3D printed resin teeth (Dentalike) were randomly divided into 4 groups (n = 15) according to the preparation method; Group 1: OneCurve only; Group 2: OneG and OneCurve; Group 3: OneFlare and OneCurve; Group 4: OneFlare, OneG, and OneCurve. During the final canal preparation procedure, the torque generated was recorded. The sum of generated torque and maximum torque were calculated. Statistical analysis was performed with one-way ANOVA and Duncan's post hoc comparison. The summed torque was reduced by glide-path preparation and coronal pre-flaring (P < 0.05), whereas the maximum torque was not reduced by the glide-path preparation (P > 0.05). It will be advantageous to create a glide-path with coronal pre-flaring to reduce the stress and reactive forces to the NiTi file and root dentin.

Vertical root fracture resistance and dentinal crack formation of root canal-treated teeth instrumented with different nickel-titanium rotary systems: an in-vitro study.

To compare the vertical root fracture (VRF) resistance of root canal-treated teeth instrumented with four different nickel-titanium (NiTi) rotary file systems and examine the dentinal crack pattern and direction using a new classification. Eighty mature mandibular premolars were selected and decoronated, leaving 13mm of the root. The root samples were mounted in acrylic resin and divided randomly into five groups of different NiTi file systems: Group 1-control, Group 2-T-Pro, Group 3-HyFlex CM, Group 4-TG6 and lastly Group 5-ZenFlex. Samples in Group 2 and Group 3 were instrumented up to size 25/0.04, whereas Group 4 and Group 5 were instrumented up to size 25/0.06. Obturation was performed with AH Plus sealer and gutta-percha using single cone technique. Subsequently, all samples were subjected to occlusal compressive force until they were fractured. The force (N) needed to cause root fracture was recorded. The crack patterns and directions were also inspected under magnification and classified using a new and simple classification. The highest (VRF) resistance was noted in the control group (453.15 ± 92.23N), followed by T-Pro (387.43 ± 76.81N), HyFlex CM (381.88 ± 52.73N), ZenFlex (369.15 ± 89.41N) and finally TG6 (346.05 ± 72.08N), but there was no significant difference between T-Pro and HyFlex (P = 0.438). A significantly higher prevalence (P = 0.001) of Type 1 crack pattern was observed, especially in samples instrumented with TG6. Majority of the cracks ran buccolingually except in some samples instrumented with ZenFlex (P = 0.898). Smaller file taper increased the VRF resistance of root canal-treated teeth. Majority of the dentinal crack exhibited Type 1 pattern and ran buccolingually.

Comparative Evaluation of Mineral Trioxide Aggregate Obturation Using Four Different Techniques-A Laboratory Study.

This study aimed to compare the density of mineral trioxide aggregate (MTA) as a root canal filling material in the apical 5 mm of artificial root canals. Forty transparent acrylic blocks with 30-degree curved canals were instrumented and allocated into four compaction technique groups (n = 10): Lawaty (hand files); gutta-percha (GP) points; auger (nickel–titanium rotary files in reverse mode); and plugger technique. Filled canals were weighed after setting the MTA to calculate difference in mass. Two postoperative radiographs compared radiopacity by measuring luminance variations at 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm from the root apex. Obturation time was measured using a digital chronometer. The significance level was set to p < 0.05. The plugger group had a lower mass. Relative luminance was significantly higher for the Lawaty group than the plugger group at all examined apical levels. The relative luminance of the auger and GP groups were significantly higher than the plugger group at depths between 0.5 mm and 2 mm. Relative luminance was highest for the Lawaty technique at all depths between 0.5 mm and 4 mm. The Lawaty technique group was associated with increased obturation time compared with pluggers. Compacting MTA in curved canals with the Lawaty technique has the highest mass and radiopacity but requires more time.

Geometric Analysis of Curved Canals Prepared by HyFlex EDM Versus HyFlex CM Rotary Nickel Titanium Files: An In-Vitro Study

Geometric Analysis of Curved Canals Prepared by HyFlex EDM Versus HyFlex CM Rotary Nickel Titanium Files: An In-Vitro Study

A comparative evaluation of canal transportation, centering ability, and volumetric increase in the curved canals using thermally treated three nickel-titanium rotary files

Aims: The aim of this study was to evaluate and compare canal transportation (CT), centering ability (CA), and volumetric changes in the curved canals prepared using Hyflex Electrical Discharge Machining (HEDM), ProTaper Gold (PG), and NeoEndo Flex rotary file systems through cone-beam computed tomography (CBCT). Materials and Method: Sixty mesiobuccal canals of maxillary molars were selected. Pre- and postinstrumentation CBCT scans were taken in the same position. CT and CA were calculated at 1 mm, 4 mm, and 7 mm from the apex; change in volume for the whole canal was measured and analyzed statistically. Results: The results showed that mean CT of HEDM and NeoEndo was less than PG at all levels, with significant differences at 4 mm and 7 mm. Regarding CA, no significant differences were found among the file systems. PG showed maximum volumetric increase with no statistically significant differences between the groups. Conclusion: All the experimental file systems respected the canal anatomy, although in the middle third, PG showed significantly more CT than HEDM and NeoEndo, whereas in the coronal third, PG showed significantly greater CT than NeoEndo. Regarding CA, no significant differences were found among the file systems. PG showed maximum volume of dentin removal.

Nickel–Titanium Rotary Instruments: An In Vitro Comparison (Torsional Resistance of Two Heat-treated Reciprocating Files)

The present study aims to evaluate the difference in torsional resistance of two reciprocating nickel-titanium (Ni-Ti) rotary files: WaveOne Gold and EdgeOne Fire. A total of 40 nickel-titanium rotary instruments (n = 40): 20 WaveOne Gold Small (WOGS) and 20 EdgeOne Fire Small (EOFS) were divided into two groups. Each instrument was tested using a torsional resistance device already validated in previous studies to evaluate and compare torsional resistance. The static torsional test was implemented by blocking each instrument at 3 mm from the tip and rotating it until fracture with a reciprocating motion. Torque to fracture (TtF) and fragment length (FL) were measured and statistically analyzed. Statistical analysis of TtF found significant differences between the two groups (p<0.05). The EOFS showed higher TtF if compared to WOGS, with a mean value and a standard deviation of 3.05 ± 0.07 (N cm) against 2.97 ± 0.08 (N cm). Data for FL showed no significant differences (p>0.05) between the two groups. According to the results of this study, it is reasonable to assert that EOFS instruments showed a higher torsional resistance if compared to the WOGS. As evidenced by this study, EOFS should be considered as a safer solution, in terms of torsional resistance, if compared to WOGS, reducing the risk of intracanal separation due to excessive torsional load.

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 &gt; 0.05) at coronal, middle, and apical level of root canal.

Impact of Peracetic Acid on the Dynamic Cyclic Fatigue of Heat-Treated Nickel-Titanium Rotary Endodontic Instrument.

Peracetic acid (PAA) is widely used as a sterilizing/disinfecting agent, and, in endodontics, it has been introduced as a promising irrigant in root canal treatment. It has been used at different concentrations to achieve various functions. However, endodontic instruments in contact with PAA of a certain concentration may affect their fatigue resistance. Therefore, the aim of this study was to investigate the impact of PAA on the cyclic fatigue resistance of three commercial heat-treated nickel-titanium (NiTi) rotary files. Three types of heat-treated NiTi rotary files were selected: One Curve (OC), ProTaper Gold (PTG), and Wave One Gold (WOG). Each type was divided into three subgroups (n = 6 for each file type): (1) untreated instruments; (2) files immersed in 0.002% PAA; and (3) files immersed in 0.35% PAA. The performance of each file type was tested in a simulated canal. The number of cycles to fracture (NCF) was determined to assess cyclic fatigue resistance of the files. Independent sample t-test was applied to compare each treated file within a subgroup with its respective control group, and one-way ANOVA was used for comparison among the main groups. All types of tested files revealed a significant decline in the cyclic fatigue resistance after exposure to 0.002% PAA except the PTG (P=0.209). After exposure of the files to a higher concentration (0.35% PAA), a dramatic reduction was demonstrated by all the groups. Before and after exposure of the files to PAA, PTG displayed the highest cyclic fatigue resistance, followed by the WOG, while the OC showed the lowest resistance. Exposure of heated-treated NiTi files to PAA in a relatively high or low concentration adversely affects the cyclic fatigue resistance. The PTG files demonstrated the best performance among the tested types and can be disinfected with 0.002% PAA for clinical purpose.

Effect of flushing temperature on preparation ability of rotary nickel-titanium files.

The effect of flushing at different temperatures on the preparation ability of rotary nickel-titanium files was investigated to provide guideline for clinical application. Sixty ProTaper Universal F1 rotary nickel-titanium files were randomly divided into three groups treated by flushing at 6°C, 23°C, and 40°C. Root canal preparation was conducted by step-by-step method on standardized nickel-titanium instrument fracture models. During preparation, the thrust force was set as 10 N, and water was continuously flushed. The motor speed was 350 rpm (rounds per minute), and the torque was 3.0 N cm. When the set torque was reached, the motor automatically rotated in the reverse direction and was pulled out. Root canal preparation was performed using ProTaper Universal F1 rotary nickel-titanium files treated by flushing. The numbers of rotations before the device was fracture were 429.33 ± 214.68, 821.92 ± 410.43, and 1304.92 ± 297.81, respectively. When each root canal was completed, the numbers of instrument rotations were 272.15 ± 88.30, 188.85 ± 34.36, and 163.41 ± 16.18, respectively. Rank sum test and analysis of variance were performed by IBM SPSS Statistics v21.0 software, and both of them were p < 0.01, indicating that the number of cycles to failure (NCF) and the number of instrument rotations for each root tube were statistically different at the three temperatures. The self-made resin-simulated curved root canal can replace the real root canal to complete the root canal preparation experiment. The group of nickel-titanium files treated by flushing at 23°C can prepare more root canals and prolong the life of nickel-titanium files than at 6°C. When flushing was done at 40°C, the number of root canals prepared by nickel-titanium files was the highest, and it was not easy to damage the instrument, but lateral perforation occurred easily during root canal preparation.

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.

Influence of voxel size on micro-CT analysis of debris after root canal preparation.

The aim of this study was to assess the influence of micro-computed tomography (micro-CT) voxel size on the evaluation of debris accumulation after passive ultrasonic irrigation (PUI) in curved root canals prepared with rotary nickel-titanium files. Mesial root canals (n = 24) of mandibular molars with curvature between 25° and 35° were prepared using ProDesign Logic 30/.05 (PDL) or HyFlex EDM 25/.08 (HEDM). PUI was performed after root canal preparation of all root canals. The specimens were scanned using high-resolution (5 μm voxel size) micro-CT imaging before and after experimental procedures. The percentage of debris was analyzed in the middle and apical thirds using images with 5, 10 and 20 μm voxel sizes. Data were compared using unpaired and paired Student's t-test, ANOVA and Tukey's statistical tests (α = 0.05). There were no differences among the debris analyses performed at different voxel sizes (5, 10 and 20 μm) (p > 0.05). The percentage of debris was similar between the root canals prepared by PDL and HEDM before and after PUI (p > 0.05). In both groups, the percentage of debris decreased in the middle third after PUI (p < 0.05). Within the limitations of this ex vivo study, it can be concluded that the voxel sizes evaluated did not have a significant impact on the analysis of accumulated debris. However, the results showed a tendency for detection of more debris in the analysis performed using a lower voxel size. PUI decreased the debris accumulation in the middle third of curved root canals.

Influence of Artificial Canal Lubricants on the Lifespan of One Curve File under Static and Dynamic Test Modes

Aim: This study was designed to determine the lifespan of One Curve (OC) heat-treated nickel-titanium (NiTi) rotary files operating under static and dynamic fatigue conditions using intracanal lubricants such as oil or sodium hypochlorite (NaOCl). Materials and Methods: The OC files were tested using an artificial zirconia canal. They were tested in air without any intracanal lubricant under static (Group 1) and dynamic (Group 4) modes, and after filling the canal with either oil (Group 2 and Group 5 under static and dynamic modes respectively) or 1% NaOCl (Group 3 and Group 6 under static and dynamic modes respectively). One Curve files were rotated freely in the canal at a speed of 350 rpm (continuous clockwise) under static mode until file failure occurred through fracture. In case of dynamic testing, the instruments were rotated at the same conditions in the canal, but with an additional back and forth movement until fracturing. The number of cycles to fracture (NCF) were recorded and statistically analysed using One Way ANOVA and Bonferroni tests. Results: Testing of the file in air demonstrated the lowest fatigue resistance, where the static test mode (NCF: 560 ± 8.25) was the worse than the dynamic mode (NCF: 636.81±14.49). On the other hand, the instruments tested under both static and dynamic modes in oil as an intracanal lubricant showed improved lifespans in terms of NCF (1193.89±7.96 and 1351.39 ± 7.06) compared to the same modes in NaOCl lubrication (878.89 ± 8.59 and 1093.82±39.08). Regardless of intracanal lubricant, the dynamic groups produced better results than the static ones. In terms of fractured length, significant differences were identified between the groups except between Group 2 and Group 6. Conclusions: Type of intracanal lubricant demonstrated a more influential effect on the file lifespan than the mode of cyclic fatigue (CF) test. The dynamic CF test utilising oil intracanal lubricant resulted the best improvement in the file lifespan.

A comparative evaluation of cyclic fatigue resistance of Reciproc Blue, WaveOne Gold and 2Shape nickel–titanium rotary files in different artificial canals

Aim: The aim of this in vitro study was to compare the cyclic fatigue resistance (CFR) of continuous rotation file systems (2Shape) and two reciprocating file systems (Reciproc Blue [RB] and WaveOne Gold [WOG]) in canals with different angulations.Materials and Method: Thirty files each of 2Shape (25, 0.06), RB R25 (25/0.08) and WOG Primary (25/0.07) were included in this study. All the instruments were used according to the manufacturers instructions in an endodontic fatigue testing block with three artificial grooves simulating root canals having angulations of 45°, 60°, and 90°. The files were allowed to rotate in the grooves, until fracture occurred and the time to fracture was recorded in seconds using digital chronometer. The data were analyzed statistically using one-way ANOVA followed by post hoc Tukey test.Results: The reciprocating file systems RB showed significantly higher CFR at all angles of curvature, i.e., 45°, 60°, and 90° (P < 0.05).Conclusions: Within the limitations of the present in vitro study, it may be concluded that RB tends to be more resistant to fracture in canals with a gentle curvature as well as may be more suited in canals with sharp and acute curvatures.

A comparative evaluation of cyclic fatigue resistance of ProTaper Gold, Dia-X, and ZenFlex nickel–titanium rotary files in the canals with different angles of curvature

A comparative evaluation of cyclic fatigue resistance of ProTaper Gold, Dia-X, and ZenFlex nickel–titanium rotary files in the canals with different angles of curvature

Analysis of the cutting efficiency of two different nickel–titanium rotary file systems: An in vitro study

Aim: The aim of this study was to evaluate and compare the cutting efficiency using two rotary nickel–titanium file systems. Materials and Methods: Thirty-two resin endo training blocks (ETBs) were divided into two groups (16 for each group). Two groups of resin blocks were instrumented using two continuous rotary nickel–titanium instruments (NeoEndo Flexfile and Blueflex Acerfile). The cutting efficiencies of instruments were quotients of the loss weights of specimens, and the time needed for instrumentation. Results: Cutting efficiency of NeoEndo Flexfile was greater than that of Blueflex Acerfile on both resin root canals (P < 0.05). Conclusion: NeoEndo Flexfile instrument was more efficient than Blueflex Acerfile on root canals.

Advantages of rotary and rotary conveyor systems in manufacturing automatization

Features of the structure and advantages of rotary technologies are considered. Keywords rotor systems; manufacturing automatization; advantages; modular systems