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Taper and stiffness of sonic endodontic files
P J Lumley1, E Harrington, A D Walmsley
1School of Dentistry, University of Birmingham, England.
Endodontics & Dental Traumatology
|April 1, 1996
Summary
Sonic endodontic files vary in taper and stiffness. Heliosonic and Shaper files conform to ISO standards, while Rispisonic files do not, impacting their flexibility and performance.
Area of Science:
- Endodontics
- Dental Materials Science
Background:
- Sonic endodontic instruments utilize specialized files for root canal preparation.
- Understanding file geometry and mechanical properties is crucial for effective and safe endodontic treatment.
Purpose of the Study:
- To measure the thickness and taper of MM1500 sonic instrument files (Heliosonic, Shaper, Rispisonic).
- To assess the stiffness of these files and correlate it with their dimensional properties.
- To compare file characteristics against International Organization for Standardization (ISO) recommendations.
Main Methods:
- Light microscopy was used to measure file diameter at 2 mm intervals (n=5 per type).
- A custom model system measured the load required for a 45-degree file tip deflection to assess stiffness.
- Analysis of variance (ANOVA) was employed for statistical comparison.
Main Results:
- Heliosonic and Shaper files exhibited linear increases in width and consistent taper, aligning with ISO standards.
- Rispisonic files showed inconsistent widths and tapers, deviating from ISO recommendations.
- Heliosonic files were significantly less flexible than Rispisonic and Shaper files across all sizes (p < 0.001), attributed to variations in cross-sectional area.
Conclusions:
- Sonic endodontic files demonstrate variability in taper and stiffness.
- Non-standardized Rispisonic files present different mechanical properties compared to Heliosonic and Shaper files.
- File design inconsistencies may influence clinical performance and safety during root canal procedures.