Fractographic analysis of separated endodontic file designs
- PDF / 2,341,873 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 64 Downloads / 171 Views
ENGINEERING AND NANO-ENGINEERING APPROACHES FOR MEDICAL DEVICES Original Research
Fractographic analysis of separated endodontic file designs J. J. Mecholsky Jr
1,2
●
A. A. Barrett2 C. T. Jones3,6 K. M. Pace4,5 U. P. Nair7 ●
●
●
1234567890();,:
1234567890();,:
Received: 13 January 2020 / Accepted: 24 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
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, torquecontrolled 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.
1 Introduction * J. J. Mecholsky Jr [email protected]fl.edu 1
Department of Materials Science & Engineering, Center for Dental Biomaterials, College of Engineering, University of Florida, Gainesville, FL 32611-6400, USA
2
Center for Dental Biomaterials, Department of Materials Science & Engineering, College of Engineering, University of Florida, Gainesville, FL 32611-6400, USA
3
Department of Endodontics, College of Dentistry, University of Florida, Gainesville, FL 32611-6400, USA
4
Department of Materials Science & Engineering, College of Engineering, University of Florida, Gainesville, FL 32611-6400, USA
5
Present address: Alight Solutions, Dallas, TX, USA
Data Loading...
