The Impact of Instrument Fracture on Outcome of Endodontic Treatment

doi:10.1097/01.don.0000164127.62864.7c

Journal of Endodontics

Volume 31, Issue 12, December 2005, Pages 845-850

https://doi.org/10.1097/01.don.0000164127.62864.7c Get rights and content

Abstract

Adoption of rotary nickel-titanium instruments has renewed concerns regarding instrument fracture and its consequences. The frequency of instrument fracture and its impact on treatment outcome were determined from an analysis of specialist endodontic practice records involving 8460 cases. A case-control study of treatment outcomes was conducted on a subset of 146 teeth with a retained instrument fragment (plus 146 matched controls), for which clinical and radiographic follow-up of at least 1 year was available. Masked radiographs were assessed by two calibrated examiners. Overall prevalence of retained fractured instruments was 3.3% of treated teeth. In the case-control study, overall healing rates were 91.8% for cases with a fractured instrument and 94.5% for matched controls (p > 0.05, Fisher’s exact test). Healing in both groups was lower in teeth with a preoperative periapical radiolucency (86.7% versus 92.9%, p > 0.05). In the hands of skilled endodontists prognosis was not significantly affected by the presence of a retained fractured instrument.

Section snippets

Study Design

This study was divided into two parts: 1) a retrospective survey of all cases treated nonsurgically (including retreatment) over some 13.5 yr in two endodontic practices involving seven endodontists. The main objective was to determine the prevalence of retained fractured instruments following treatment; 2) the second part was based on all cases from part 1 for which clinical and radiographic follow-up for at least 1 yr was available. Specifically, it entailed a retrospective, case-control

Cohen's Kappa Values

The Kappa value for the interobserver agreement was κ = 0.73. The intraobserver Kappa values for the two raters were κ = 0.68 and 0.78. All three Kappa values were in the “substantial agreement” category (²²).

Fracture Prevalence

Overall, 277 teeth from 8460 teeth were identified as containing one or more instrument fragments (total = 301 fragments), yielding a prevalence of all types of retained fractured endodontic instruments of 3.3%, from two specialist practices screened for the period January 1990 to May 2003

Discussion

The prospective, randomized controlled clinical trial is the gold standard by which all clinical research is judged because it represents the highest grade of evidence that can be used for the provision of evidence-based health care (⁹). However, the best level of evidence that can be realistically achieved for an evaluation of the impact of a procedural complication such as a fractured instrument on endodontic treatment outcome, is a case-control study; although, some would argue that a

Conclusions

a) The overall frequency of fractured endodontic instruments left in the root canal after treatment was found to be 3.3% of treated teeth and comprised 78.1% rotary NiTi files, 15.9% SS hand files, 4.0% paste fillers, and 2.0% lateral spreaders. The frequency of rotary NiTi instrument breakage was comparable to that previously reported for hand files.

b) In the hands of experienced operators, endodontic instrument fracture, in particular rotary NiTi, had no adverse influence on the outcome of

Acknowledgments

The authors would like to thank the following for their valuable assistance in the research project: Associate Professor Ian Gordon of the Statistical Consulting Centre, University of Melbourne, Drs. Vivian Jeng and Pairoj Linsuwanont of the School of Dental Science, University of Melbourne, and all the endodontists—in particular, the practice principals Drs. Garry Nervo and Peter Parashos—of the participating endodontic practices for their cooperation, patience, and contribution of cases to

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Comparative evaluation of the newly introduced; RACE EVO file system to the currently well-performing file systems like HyFlex EDM OneFile, Vortex Blue, ProTaper Gold (PTG) with regards to the cyclic fatigue resistance.
&Methods.
The endodontic rotary files under evaluation were segregated into four groups as follows:; RACE EVO, PTG, Vortex Blue, and HyFlex EDM OneFile. A detailed physical analysis of the cyclic fatigue resistance was performed in 15 files of each type (n = 60). Under the test conditions of 37 °C the test samples were subjected to continuous motion at the manufacturer recommended speed within an artificial curved canal until it fractured. For all the test samples, with the recording of time of fracture, calculation was done for number of cycles to fracture (NCF). In addition, the length of the fractured segment was determined. The fractured surface was further evaluated with scanning electron microscopic (SEM) images.
Highest significance for NCF was seen in HyFlex EDM OneFile followed by the Vortex Blue, PTG, and; RACE EVO (p < 0.05) by analyzing the data statistically. Significant differences among the lengths of the fractured segments were evident among tested files, ranging between 4.73 and 6.3 mm (p < 0.05) with HyFlex EDM OneFile uniquely differentiating from the others showing the fracture at 6.3 mm. The common features of cyclic fatigue failure was further substantiated by SEM images.
Compared to the HyFlex EDM OneFile, Vortex Blue, and PTG files; RACE EVO demonstrated significantly lower resistance to cyclic fatigue.
Comparative Evaluation of a Dynamic Navigation System versus a Three-dimensional Microscope in Retrieving Separated Endodontic Files: An In Vitro Study
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This study aimed to compare the effectiveness of a dynamic navigation system and a three-dimensional microscope in retrieving broken rotary Nickel-Titanium files when using trepan burs and the extractor system.
Thirty maxillary first bicuspids with 60 separate roots were split into 2 comparable groups based on a comprehensive cone beam computed tomography analysis of the root length and curvature. After standardized access opening, glide paths, and patency attainment with the K file (sizes 10 and 15), the teeth were arranged on 3D models (three per quadrant, six per model). Subsequently, controlled-memory heat-treated Nickel-Titanium rotary files (#25/0.04) were notched 4 mm from the tips and fractured at the apical third of the roots. The C-FR1 Endo file removal system was employed under both guidance to retrieve the fragments, and the success rate, canal aberration, treatment time, and volumetric changes were measured. The statistical analysis was performed using IBM SPSS software at a significance level of 0.05.
The microscope-guided group had a higher success rate than the dynamic navigation system guidance, but the difference was insignificant (P > .05). In addition, the microscope-guided drills resulted in a substantially lower proportion of canal aberration, shorter time to retrieve the fragments and less change in the root canal volume (P < .05).
Although dynamically guided trephining with the extractor can retrieve separated instruments, it is inferior to three-dimensional microscope guidance regarding treatment time, procedural errors, and volume change.
Endodontic Clinical Outcome after Separated Instrument Removal Using a Spinal Needle Technique: A Retrospective Study of Thirty Years of Clinical Experience
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Current methods for the removal of separated endodontic instruments (RSI) are not predictable.
The primary outcome of this retrospective study was to assess the clinical and radiographic success (CRS) of teeth in case of RSI after a 5-year follow-up. Secondary outcomes were to evaluate (1) the effectiveness in RSI and (2) the risk of root fracture after RSI. The study protocol was registered at ClinicalTrials.gov (ID: NCT05128266). The patients were treated by the same endodontist between January 1991 and December 2019. The RSI was performed under the operative microscope as follows: first, the dentine surrounding the coronal part of the broken instrument was selectively removed by using a small ultrasonic tip to loosen the fragment; then, a modified spinal needle was used to catch and remove the instrument. The 1-, 3-, 5-, and >5-year CRS were recorded. Logistic regression analysis was performed to determine independent predictors of failure (ie, tooth number, type of root canal, shape of the root canal, type of broken instrument, apicocoronal level of the separated instrument, presence of periapical lesions, and root perforations).
A total of 158 teeth were included in this study. Finally, 131 instruments underwent RSI (82.9%). RSI was an independent predictor of CRS after 1-year of treatment (odds ratio: 58.3; 95% confidence interval: 27.42–95.73, P < .05). At the 5-year follow-up, only 10 of 131 teeth (7.6%) failed. All failures were caused by root fracture (10/10) (χ² test, P < .05). Separated instruments located in the apical third of the root were more difficult to remove (13/49 cases, 26.5%; χ² test, P < .05).
The proposed technique can achieve excellent effectiveness in RSI, can achieve a high CRS rate when a periapical lesion is present, is not associated to a significant increase in root fracture incidence, and should be performed with the help of an operative microscope.
Diamondlike Carbon Surface Treatment Improves the Fatigue Resistance of Ultrasonic Tips
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The aim of this study was to compare E1-Irrisonic (Helse Ultrasonics, Ocoee, FL) and Irri Black (Helse Ultrasonics), a novel ultrasonic tip with diamondlike carbon treatment, regarding their design, metallurgy, microhardness, bending resistance, and time to fracture under the oscillatory fatigue test.
A total of 17 E1-Irrisonic and 17 Irri Black new ultrasonic tips were selected. The tip geometry and surface finishing were assessed using scanning electron microscopy. The elemental composition was defined by energy-dispersive X-ray spectroscopy. Hardness Knoop was calculated using a microhardness tester. The maximum load required to displace the instrument in 45° was recorded in gram/force, oscillatory fatigue was measured in seconds at the moment of instrument fracture, and the size of the separate fragments was determined in millimeters. The Student t test was used for statistical comparison (α = 5%).
Scanning electron microscopic analyses revealed that E1-Irrisonic had a flat end tip, whereas a noncutting rounded tip was observed in Irri Black. The surface of E1-Irrisonic was smoother than Irri Black, which was irregular. Energy-dispersive X-ray spectroscopic analyses showed that the elemental compositions of the E1-Irrisonic and Irri Black tips were consistent with stainless steel and titanium-aluminum alloys, respectively. Irri Black showed significantly higher bending load resistance, time to fracture under oscillatory motion, and hardness Knoop than the E1-Irrisonic tip (P < .05), whereas the length of fragments was similar (P > .05).
Diamondlike carbon treatment improved hardness Knoop and reduced the flexibility of the Irri Black ultrasonic tip, improving its time to fracture under oscillatory motion compared with the nontreated E1-Irrisonic tip.
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Clinical ResearchThe Impact of Instrument Fracture on Outcome of Endodontic Treatment

Abstract

Section snippets

Study Design

Cohen's Kappa Values

Fracture Prevalence

Discussion

Conclusions

Acknowledgments

Oral Surg Oral Med Oral Pathol

J Am Dent Assoc

J Endod

J Endod

J Endod

J Endod

J Endod

J Endod

J Endod

J Endod

The dependence of the results of pulp therapy on certain factors: an analytical study based on radiographic and clinical follow-up examinations

Acta Odontol Scand

The Washington study

Filling root canals with files. Radiographic evaluation of 304 cases

NY State Dent J

Evidence-based medicine: how to practice and teach EBM

Randomized, controlled trials, observational studies, and the hierarchy of research designs

New Engl J Med

Clinical Research
The Impact of Instrument Fracture on Outcome of Endodontic Treatment