A comparative study of root canal preparation with NiTi-TEE and K3 rotary Ni-Ti instruments

Fracture Incidence of Kedo-S Square Pediatric Rotary Files: A Prospective Clinical Study

Objective  The primary focus of this clinical study was to analyze the probability of occurrence of instrument fracture after root canal preparation of primary molars with the help of Kedo-S Square pediatric rotary file.

Materials and Methods  Three experienced specialists treated 100 primary maxillary and mandibular molars (335 root canals) using a standardized protocol over 2 months. Biomechanical preparations were carried out using Kedo-S Square file, as per the suggestions given by the manufacturer. Every instrument in Group A helped handle three clinical cases, while for groups B, C and D, they helped in handling 5, 9, and 12 cases, respectively. Making use of an operational microscope, the rotary files, after being pulled out from the canal, were observed. The values were tabulated, and descriptive statistics were performed.

Results  There were two fractures (2%), of which 1 occurred in group C in the apical 1/3rd of distobuccal canal of maxillary molar, and the other occurred in group D in the apical 1/3rd of mesiobuccal canal of maxillary molar.

Conclusions  The fracture rate of Kedo-S Square rotary file is quite low. It is primarily in the buccal canals of the maxillary molars and the apical third of the root canal that the instrument has a greater probability of separation.

Computed tomography evaluation of rotary systems on the root canal transportation and centering ability

The endodontic preparation of curved and narrow root canals is challenging, with a tendency for the prepared canal to deviate away from its natural axis. The aim of this study was to evaluate, by cone-beam computed tomography, the transportation and centering ability of curved mesiobuccal canals in maxillary molars after biomechanical preparation with different nickel-titanium (NiTi) rotary systems. Forty teeth with angles of curvature ranging from 20° to 40° and radii between 5.0 mm and 10.0 mm were selected and assigned into four groups (n = 10), according to the biomechanical preparative system used: Hero 642 (HR), Liberator (LB), ProTaper (PT), and Twisted File (TF). The specimens were inserted into an acrylic device and scanned with computed tomography prior to, and following, instrumentation at 3, 6 and 9 mm from the root apex. The canal degree of transportation and centering ability were calculated and analyzed using one-way ANOVA and Tukey's tests (α = 0.05). The results demonstrated no significant difference (p > 0.05) in shaping ability among the rotary systems. The mean canal transportation was: -0.049 ± 0.083 mm (HR); -0.004 ± 0.044 mm (LB); -0.003 ± 0.064 mm (PT); -0.021 ± 0.064 mm (TF). The mean canal centering ability was: -0.093 ± 0.147 mm (HR); -0.001 ± 0.100 mm (LB); -0.002 ± 0.134 mm (PT); -0.033 ± 0.133 mm (TF). Also, there was no significant difference among the root segments (p > 0.05). It was concluded that the Hero 642, Liberator, ProTaper, and Twisted File rotary systems could be safely used in curved canal instrumentation, resulting in satisfactory preservation of the original canal shape.

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.

Shaping ability of nickel-titanium rotary instruments in curved root canals

INTRODUCTION

Disinfection and subsequent obturation of the root canal space require adequate mechanical enlargement of the canals. The purpose of this in vitro study was to compare the shaping ability of Mtwo, RaCe and Medin rotary instruments during the preparation of curved root canals.

MATERIALS AND METHODS

Sixty mesiobuccal root canals of mandibular molars with severe curvatures between 25-35(°) and radius of 4-9 mm were randomly divided into three groups of 20 canals each. Using pre- and post-instrumentation radiographs, straightening of the canal and the apical transportation were determined with AutoCAD software. The data were analyzed using Chi square, analysis of variance, and post-hoc tests and the significance level was set at P<0.05.

RESULTS

Mtwo instruments maintained the canal curvature significantly better than Race and Medin instruments (P<0.05). There was significant difference between the rotary instruments for iatrogenic transportation of the major foramen (P>0.05).

CONCLUSIONS

Under the conditions of this in vitro study, Mtwo instruments seemed superior to the two other rotary instruments.

Cutting efficiency of four different rotary nickel: Titanium instruments

Aim:

The aim of this study was to evaluate the cutting efficiency of rotary nickel-titanium (NiTi) instruments K3, NiTi Tee, Profile, and Quantec with taper size 04/25.

Materials and Methods:

The number of samples was 10 for each group (n = 10). The cutting efficiency was measured by the mass loss from each acrylic resin block after instrumentation of a simulated canal using the Crown-down technique.

Results:

The analysis of variance (ANOVA) showed that there was a statistically significant difference among the studied groups. The Tukey's test showed that the acrylic resin blocks prepared with instruments K3 (0.00369 ± 0.00022), NiTi Tee (0.00368 ± 0.00023), and Profile (0.00351 ± 0.00026) presented the greatest mass loss, showing no statistically significant difference among them (P < 0.05). The lowest mass loss was found in the blocks prepared with Quantec instruments (0.00311 ± 0.0003) (P < 0.05).

Conclusions:

It could be concluded that the K3, NiTi Tee, and Profile instruments presented a greater cutting efficiency than the Quantec instruments.

[Scanning electron microscopy investigation of canal cleaning after canal preparation with nickel titanium files]

INTRODUCTION

Root canal preparation is the most important phase of endodontic procedure and it consists of adequate canal space cleaning and shaping. In recent years, rotary instruments and techniques have gained importance because of the great efficacy, speed and safety of the preparation procedure.

OBJECTIVE

The aim of this research was to investigate the influence of different NiTi files on the canal wall cleaning quality, residual dentine debris and smear layer.

METHODS

The research was conducted on extracted human teeth in vitro conditions. Teeth were divided in 7 main groups depending on the kind of instruments used for root canal preparation: ProTaper, GT, ProFile, K-3, FlexMaster, hand ProTaper and hand GT. Root canal preparation was accomplished by crown-down technique. Prepared samples were assessed on scanning electron microscopy JEOL, JSM-6460 LV. The evaluation of dentine debris was done with 500x magnification, and the evaluation of smear layer with 1,000 times magnification. Quantitive assessment of dentine debris and smear layer was done according to the criteria of Hulsmann.

RESULTS

The least amount of debris and smear layer has been found in canals shaped with ProFile instruments, and the largest amount in canals shaped with FlexMaster instruments. Canal cleaning efficacy of hand GTand ProTaperfiles has been similar to cleaning efficacy of rotary NiTi files. Statistic analysis has shown a significant difference in amount of dentine debris and smear layer on the canal walls between sample groups. shaped with different instruments.

CONCLUSION

Completely clean canals have not been found in any tested group of instruments. The largest amount of debris and smear layer has been found in the apical third of all canals. The design and the type of endodontic instruments influence the efficacy of the canal cleaning.

Comparison of root canal preparation with two rotary NiTi instruments: ProFile .04 and GT Rotary

AIM

To compare root canal preparation using ProFile .04 and GT Rotary nickel-titanium instruments (both Dentsply Maillefer, Ballaigues, Switzerland).

METHODOLOGY

Fifty extracted mandibular molars with mesial root canal curvatures between 20 and 40 degrees were randomly divided into two groups and embedded in a muffle system. All root canals were prepared to size 45 using ProFile .04 or GT rotary instruments. The following parameters were evaluated: straightening of root canal curvature, postoperative root canal cross-section, cleaning ability, safety issues and working time.

RESULTS

Both NiTi systems maintained curvature well; the mean degree of straightening was <1 degrees . The majority of the root canals prepared with ProFile .04 (80.8%) and GT (84.0%) postoperatively showed a round or oval cross-section. For debris, ProFile .04 and GT rotary achieved 67.1% and 71.6% scores of 1 and 2, respectively. Concerning the coronal region statistical analysis showed a better result for GT than for ProFile .04. For the middle and apical thirds of the root canals, results did not differ significantly. None of the two systems completely removed smear layer. Ten procedural incidents occurred with ProFile .04 compared with five with GT. Mean working time was shorter for ProFile .04 (131.8 s) than for GT (143.7 s); the difference was not significant.

CONCLUSIONS

Both systems respected original root canal curvature well and were safe to use. Smear layer removal was not satisfactory with either systems.

Rotary NiTi Instrument Fracture and its Consequences

The fracture of endodontic instruments is a procedural problem creating a major obstacle to normally routine therapy. With the advent of rotary nickel-titanium (NiTi) instruments this issue seems to have assumed such prominence as to be a considerable hindrance to the adoption of this major technical advancement. Considerable research has been undertaken to understand the mechanisms of failure of NiTi alloy to minimize its occurrence. This has led to changes in instrument design, instrumentation protocols, and manufacturing methods. In addition, factors related to clinician experience, technique, and competence have been shown to be influential. From an assessment of the literature presented, we derive clinical recommendations concerning prevention and management of this complication.