Incidence Of Instrument Fracture Research Articles

Life span of Neoendo Flex and ProTaper Next rotary files with reciprocating motion in single-rooted teeth.

Cleaning and shaping represent a vital step in the endodontic procedure. In routine endodontic therapy, the fracture of nickel-titanium (NiTi) instruments is a procedural problem creating a major obstacle to therapy. This study examines the life span of one Neoendo Flex and ProTaper Next (PTN) rotary file using reciprocating motion and compares the time required by both file systems for canal preparation. One hundred maxillary permanent central incisors were selected. In that, fifty teeth are utilized in a reciprocating motion (RM) with the PTN file (n = 25) and Neoendo Flex file (n = 25). To check fractured resistance and the overall root canal preparation time, fifty more teeth are employed in continuous motion (CM) with canals prepared using PTN (n = 25) and Neoendo Flex (n = 25). All canals are prepared following the sequence of respective files. Later, the fracture mechanism of the files was inspected using a scanning electron microscope. In an RM motion, both PTN and Neoendo Flex files can be used in a minimum of 25 canals in single-rooted teeth. Statistical analysis using the Mann-Whitney U-test showed no significant difference in total time taken by PTN and Neoendo Flex in both motions. Within the limitation of this study, the RM was found to be better than CM with less incidence of instrument fracture.

A comparative study of root canal shaping using protaper universal and protaper next rotary files in preclinical dental education.

BackgroundDentistry has undergone an evolution in endodontics practice caused by the advancement of rotary techniques for root canal preparation and their subsequent incorporation into the teaching of dentistry undergraduates. This research aimed to evaluate the shaping ability of third-year dental students as their first experience in rotary instrumentation using ProTaper Universal (PTU) and ProTaper Next (PTN) (Dentsply Maillefer) rotary instruments in simulated curved canals.MethodsForty students instrumented 200 simulated canals with a 40° curvature in resin blocks according to the manufacturer’s instructions with PTU and 39 students and 195 canals with PTN files. The canals were prepared at a speed of 300 rpm using a 16:1 reduction hand-piece powered by an electric motor (Xsmart; Dentsply Maillefer). The final apical preparation was set to F2 for the PTU and X2 for the PTN group. The change in canal curvature was evaluated based on Schneider technique using the AutoCAD 2007 software on post-digital photographs. The incidence of instrument fracture and deformation, the incidence of ledge, the change in working length (WL), and the working time were noted. The data were analyzed with Student’s t-test and Chi-Square test at a significance level of 0.05 using SPSS.ResultsPTN maintained the original canal curvature better, resulting in fewer fractures and ledges, and shaped the canals faster than the PTU (P < 0.05). The mean curves of the resin canals after the instrumentation for the PTU and PTN groups were 24.03° ± 3.14° and 25.64° ± 2.72°, respectively. Thirty-three (17.4%) PTU and 18 (9.3%) PTN files fractured (p < 0.05). Nine (4.5%) PTU and 2 (2.6%) PTN deformed (p > 0.05). The change in WL after instrumentation was 0.97 mm ± 0.95 mm in PTU and 0.96 mm ± 0.80 mm in PTN (p < 0.05). The mean times were 627 s ± 18 s for PTU and 379 s ± 18 s for PTN (p < 0.000).DiscussionPTN can be recommended in severely curved root canals in terms of maintenance of the original canal curvature, superior instrument fracture and fewer ledges. Even if training before preparation provides an acceptable level of canal shaping for preclinical students, the use of NiTi rotary instruments should be included in the undergraduate dental curriculum, contributing to an increase in the quality of root canal shaping and, consequently, to an improvement of the clinical experience of students.

Micro-computed tomographic evaluation of canal retreatments performed by undergraduate students using different techniques.

ObjectivesThis study evaluated the amount of remaining root canal filling materials after retreatment procedures performed by undergraduate students using manual, rotary, and reciprocating techniques through micro-computed tomographic analysis. The incidence of instrument fracture and the instrumentation time were also evaluated.Materials and MethodsThirty maxillary single rooted teeth were prepared with Reciproc R25 files and filled with gutta-percha and AH Plus sealer by the continuous wave of condensation technique. Then, the specimens were assigned to 3 groups (n = 10), according to the retreatment technique used: manual, rotary, and reciprocating groups, which used K-file, Mtwo retreatment file, and Reciproc file, respectively. Retreatments were performed by undergraduate students. The sample was scanned after root canal filling and retreatment procedures, and the images of the canals were examined to quantify the amount of remaining filling material. The incidence of instrument fracture and the instrumentation time were recorded.ResultsRemaining filling material was observed in all specimens regardless of the technique used. The mean volume of remaining material was significantly lower in the Reciproc group than in the manual K-file and Mtwo retreatment groups (p < 0.05). The time required to achieve a satisfactory removal of canal filling material and refinement was significantly lower in the Mtwo retreatment and Reciproc groups (p < 0.05) when compared to the manual K-file group. No instrument fracture was observed in any of the groups.ConclusionsReciproc was the most effective instrument in the removal of canal fillings after retreatments performed by undergraduate students.

Failure of ProTaper rotary Ni-Ti instruments used by undergraduate students

Objective: To evaluate the effect of number of uses, angle and radius of curvature and type of instrument on the fracture of ProTaper rotary instruments when used by undergraduate students. Study Design: Three hundred and seventy-six molars, with a total of 1114 root canals, extracted were instrumented by undergraduate students using ProTaper instruments according to the manufacturer´s recommendations. When fracture occurred, data were collected concerning the number of uses, type of instrument, level of fracture, angle and radius of curvature. ANOVA test were used to determine the influence of type of instrument in the incidence of instrument fracture. Logistic regression model was used to determine the influence of number of uses, angle and radius of curvature in the incidence of instrument fracture. Significance was set at p< 0.05. Results: A total of 37 Ni-Ti rotary instruments fractured during the treatment. Fracture occurred in 9.84% (37/376) of the teeth treated and 3.32% of the canals prepared with Ni-Ti rotary instruments (37/1114). A decrease in the radius of curvature of the canal significantly increased the likelihood of fracture (p=0.0001). Instrument fracture significantly increased as the number of uses increased (p=0.0037). No significant differences were found between the 6 types of ProTaper instruments (p=0.8). A reduction in the angle of curvature did not produce a significant decrease in the incidence of instrument separation (p=0.08). Conclusions: The results of this study imply that instrument fracture is linked to radius of curvature and number of uses. Key words:Fracture, ProTaper ®, root canal preparation, undergraduate students.

Nickel–titanium rotary instrument fracture: a clinical practice assessment

To prospectively determine the incidence of nickel-titanium rotary instrument fracture in an endodontic clinical practice setting. Eleven second year endodontic residents, using four nickel-titanium rotary instrument systems (ProFile, ProTaper, GTRotary and K3Endo) according to the recommendations of the manufacturers, instrumented 3181 canals in 1403 teeth of 1235 patients, in a dental school post-graduate endodontic clinic, in 1 year. The incidence of instrument fracture was determined based on the number of instruments used. When fracture occurred, data were collected concerning the type, size, taper and prior use of the fractured instruments, the length and location of the fragment within the root canal and the curvature of the canal. The overall incidence of instrument fracture was 0.39%. The incidence of fracture for ProFile, ProTaper, GTRotary and K3Endo files was 0.28%, 0.41%, 0.39% and 0.52%, respectively. There was no statistically significant difference between instrument systems. The percentage of teeth in which instruments fractured was 1.9% (0.28% for anterior teeth, 1.56% for pre-molars and 2.74% for molars). A total of 26 instruments fractured, of which 23 had tapers of 0.06 or greater. Most of the fragments were located in the apical third of the root canal, and both the median and mode amongst the fragment lengths were 2 mm. The low incidence of nickel-titanium rotary instrument fracture supports the continued use of these instruments in root canal treatment.

Fracture of ProFile nickel–titanium rotary instruments: a laboratory simulation assessment

To determine the incidence of ProFile nickel-titanium rotary instrument fracture in an endodontic laboratory simulation. Three hundred and sixty dental students used 2880 ProFile nickel-titanium rotary instruments to prepare 1440 simulated root canals in 720 plastic teeth, and another 2880 ProFile nickel-titanium rotary instruments to prepare 1440 natural root canals in 720 extracted teeth. A standardized crown-down rotary instrumentation technique was used, which included measures to prevent fracture. Rotary instrument fracture was monitored during and after completion of the laboratory simulation exercises to determine the incidence of fracture. When fracture occurred, data were collected concerning the size of the instrument, the length of the instrument fragment, the location of the fragment in the canal and the curvature of the canal in which the instrument fractured. The incidence of instrument fracture was 0.41% in plastic simulated canals and 0.31% in natural root canals. The overall incidence of instrument fracture was 0.36%. Of the instruments that fractured 67% were size 25, 0.04 taper; and 81% of the fragments were located in the apical third of the canal. The mean, median and mode of the fragment lengths were all 3 mm. The low overall incidence of fracture in this study suggests that ProFile rotary instruments are safe for use by dental students in laboratory simulations and that if preventive measures are taken the incidence of instrument fracture can be minimized.

Analysis of forces developed during mechanical preparation of extracted teeth using Profile NiTi rotary instruments

The aim of this study was to analyse the vertical forces and torque developed in the root canal system of extracted teeth during mechanical preparation using ProFile NiTi instruments. Instrument wear and fracture is in great part due to the repeated application of forces and torque during the course of root-canal preparation but research into the direct relationship has been hampered by the lack of adequate measuring devices. Measurements of these forces and torque were made with a new force analyser device, the Endographe, that was equipped with a holder to record and generate graphs of the vertical forces and torque exerted during the preparations. These preparations was performed by endodontists or students either with a series of instruments of increasing size or with the crown-down pressureless technique. The mean values for the endodontists of the generated vertical forces and torque varied, respectively, from 4 to 6N and from 7.105 to 12.105 Nm for the step-back technique and from 2.9 to 4.2 N and from 18.105 to 20.105 Nm for the crown-down technique. This suggested that the crown-down technique generated lower stresses (lower torque and lower vertical forces), although these findings also depend on the shape of individual canals. The students initially showed wide variations in generated forces, with significantly lower vertical force the torque values. By the end of the experimental sessions their values were similar to those of the endodontists, which indicated improvement in the efficiency of manipulation. Further work is needed to investigate the relationship between the force and the torque data from this study and the incidence of instrument fracture with the two techniques, as the clinical implications are considerable. It must be noted, however, that the Endographe is unable to take into account the cutting efficiency of the instruments. The use of graphs provides a new approach to the analysis of mechanical preparation.