Skip to main content

Advertisement

SpringerLink
Log in

Fractographic analysis of separated endodontic file designs

  • Engineering and Nano-engineering Approaches for Medical Devices
  • Original Research
  • Published:
Journal of Materials Science: Materials in Medicine Aims and scope Submit manuscript

Abstract

Endodontic rotary files are cutting instruments used to perform root canal procedures within a tooth interior. Focusing on quantitative fractographic analysis increases necessary, clinical performance understanding of file separation failure. This research employed controlled, dynamic testing to failure of commercial rotary files, analyzing the fractographic, forensic characteristics in relation to Weibull reliability determination, considering: (1) design analysis; (2) stress concentrations; (3) times to failure; (4) number of cycles to failure (NCF). Ex vivo testing included three file designs, each having constant tip size (0.035 mm), taper (0.06 mm/mm), and length (25 mm). Files were individually tested using an electric, torque-controlled handpiece, rotating within a standardized, simulated canal until fracture separation occurred. Fractographic analysis, including critical measurements, was conducted using the scanning electron microscope (SEM) (PhenomProX, PhenomWorld, NL). Weibull statistical analysis established reliability factors per design group. Fractographic analysis identified separation fractures, processing inclusions, flexural-fatigue striations, and stress concentrations at flute pitches. Calculated NCF median values (1277—EE; 899—VB; 713—PI) demonstrated significant statistical differences among groups (p < 0.001). Separated apical fragments yielded statistically significant differences (p ≤ 0.05) for varying file design groups. Weibull moduli among groups were statistically equivalent. Fractographic analysis exposed a presence of multiple failure factors in addition to defect distribution, governing cyclic fatigue failure originating at stress concentration points irrespective of file design. Fractographic analysis indicated that a change in file design, specifically at the working edges, in addition to improved surface finish, has the potential of reducing failures by lowering points of stress concentration and reducing fracture initiating surface cracks.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7

Similar content being viewed by others

References

  1. Civjan S, Huget EF, DeSimon LB. Potential applications of certain nickel-titanium (nitinol) alloys. J Dent Res. 1975;54:89–96.

    Article  CAS  Google Scholar 

  2. Walia HM, Brantley WA, Gerstein H. An initial investigation of the bending and torsional properties of Nitinol root canal files. J Endod. 1988;14:346–51.

    Article  CAS  Google Scholar 

  3. Zinelis S, Eliades T, Eliades G. A metallurgical characterization of ten endodontic Ni-Ti instruments: assessing the clinical relevance of shape memory and superelastic properties of Ni-Ti endodontic instruments. Int Endod J. 2010;43:125–34.

    Article  CAS  Google Scholar 

  4. Celik D, Tasdemir T, Er K. Comparative study of 6 rotary nickel-titanium systems and hand instrumentation for root canal preparation in severely curved root canals of extracted teeth. J Endod. 2013;39:278–82.

    Article  Google Scholar 

  5. Pedir SS, Mahran AH, Beshr K, Baroudi K. Evaluation of the factors and treatment options of separated endodontic files among dentists and undergraduate students in riyadh area. J Clin Diagn Res. 2016;10:ZC18–23.

    Google Scholar 

  6. Plotino G, Grande NM, Cordaro M, Testarelli L, Gambarini G. A review of cyclic fatigue testing of nickel-titanium rotary instruments. J Endod. 2009;35:1469–76.

    Article  Google Scholar 

  7. Shen Y, Cheung GS, Peng B, Haapasalo M. Defects in nickel-titanium instruments after clinical use. Part 2: fractographic analysis of fractured surface in a cohort study. J Endod. 2009;35:133–6.

    Article  Google Scholar 

  8. Peng B, Shen Y, Cheung GS, Xia TJ. Defects in ProTaper S1 instruments after clinical use: longitudinal examination. Int Endod J. 2005;38:550–7.

    Article  CAS  Google Scholar 

  9. Gao Y, Shotton V, Wilkinson K, Phillips G, Johnson WB. Effects of raw material and rotational speed on the cyclic fatigue of ProFile Vortex rotary instruments. J Endod. 2010;36:1205–9.

    Article  Google Scholar 

  10. Johnson E, Lloyd A, Kuttler S, Namerow K. Comparison between a novel nickel-titanium alloy and 508 nitinol on the cyclic fatigue life of ProFile 25/.04 rotary instruments. J Endod. 2008;34:1406–9.

    Article  Google Scholar 

  11. Al-Hadlaq SM, Aljarbou FA, AlThumairy RI. Evaluation of cyclic flexural fatigue of M-wire nickel-titanium rotary instruments. J Endod. 2010;36:305–7.

    Article  Google Scholar 

  12. Larsen CM, Watanabe I, Glickman GN, He J. Cyclic fatigue analysis of a new generation of nickel titanium rotary instruments. J Endod. 2009;35:401–3.

    Article  Google Scholar 

  13. Quinn G. Fractography of ceramics and glasses. NIST Special Publication, National Institute of Standards and Technology, Gaithersburg, MD, 2016. p. 960–16e2.

  14. Mecholsky J, Powell S. Fractography of ceramic and metal failures. West Conshohoken, PA: ASTM Internatioal; 1984.

    Book  Google Scholar 

  15. Mecholsky J. Quantitative fractography: an assessment. In: Fractography of glasses and ceramic. The American Ceramic Society, Westerville OH, 1991. p. 413–51.

  16. Pruett JP, Clement DJ, Carnes DL Jr. Cyclic fatigue testing of nickel-titanium endodontic instruments. J Endod. 1997;23:77–85.

    Article  CAS  Google Scholar 

  17. Freiman S, Mecholsky J. The fracture of brittle materials: testing and analysis. John Wiley & Sons, Hoboken, NJ, 2012.

  18. Robertson SW, Ritchie RO. In vitro fatigue-crack growth and fracture toughness behavior of thin-walled superelastic Nitinol tube for endovascular stents: a basis for defining the effect of crack-like defects. Biomaterials. 2007;28:700–9.

    Article  CAS  Google Scholar 

  19. Robertson SW, Ritchie RO. A fracture-mechanics-based approach to fracture control in biomedical devices manufactured from superelastic Nitinol tube. J Biomed Mater Res B Appl Biomater. 2008;84:26–33.

    Article  CAS  Google Scholar 

  20. Newman J, Raju I. An empirical stress-intensity factor equation for the surface crack. Eng Fract Mech. 1981;15:185–92.

    Article  Google Scholar 

  21. Taylor J. An introduction to error analysis. 2nd ed. Sausalito, California: University Science Books; 1997.

    Google Scholar 

  22. Tang WR, Smales RJ, Chen HF, Guo XY, Si HY, Gao LM, et al. Prevention and management of fractured instruments in endodontic treatment. World J Surg Proced. 2015;5(1):82–98.

  23. Gao Y, Gutmann JL, Wilkinson K, Maxwell R, Ammon D. Evaluation of the impact of raw materials on the fatigue and mechanical properties of ProFile Vortex rotary instruments. J Endod. 2012;38:398–401.

    Article  Google Scholar 

  24. Santos Lde A, Bahia MG, de Las Casas EB, Buono VT. Comparison of the mechanical behavior between controlled memory and superelastic nickel-titanium files via finite element analysis. J Endod. 2013;39:1444–7.

    Article  Google Scholar 

Download references

Acknowledgements

The authors appreciate the intellectual contributions and participation of Dr. N.J. Ruzycki, Director of Undergraduate Laboratories and the MSE Student Lab for SEM instrumentation consultation (Materials Science & Engineering, College of Engineering, UF). Authors thank Endoscopy Replacement Parts, Inc. (FL 32669) for fabrication of the precision testing block.

Author information

Author notes

  1. K. M. Pace

    Present address: Alight Solutions, Dallas, TX, USA

  2. C. T. Jones

    Present address: Practice Limited to Endodontics, Melbourne, FL, USA

  3. U. P. Nair

    Present address: Practice Limited to Endodontics, Dallas, TX, USA

Authors and Affiliations

  1. Department of Materials Science & Engineering, Center for Dental Biomaterials, College of Engineering, University of Florida, Gainesville, FL, 32611-6400, USA

    J. J. Mecholsky Jr

  2. Center for Dental Biomaterials, Department of Materials Science & Engineering, College of Engineering, University of Florida, Gainesville, FL, 32611-6400, USA

    J. J. Mecholsky Jr & A. A. Barrett

  3. Department of Endodontics, College of Dentistry, University of Florida, Gainesville, FL, 32611-6400, USA

    C. T. Jones

  4. Department of Materials Science & Engineering, College of Engineering, University of Florida, Gainesville, FL, 32611-6400, USA

    K. M. Pace

Authors
  1. J. J. Mecholsky Jr
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. A. A. Barrett
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. C. T. Jones
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. K. M. Pace
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. U. P. Nair
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to J. J. Mecholsky Jr.

Ethics declarations

Conflict of Interest

The authors declare that they have no conflict of interest.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Mecholsky, J.J., Barrett, A.A., Jones, C.T. et al. Fractographic analysis of separated endodontic file designs. J Mater Sci: Mater Med 31, 104 (2020). https://doi.org/10.1007/s10856-020-06432-3

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1007/s10856-020-06432-3

Search

Navigation