Defect propagation in NiTi rotary instruments: a noncontact optical profilometry analysis

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Materials

Background:

• Nickel-titanium (NiTi) instruments are widely used in endodontics.
• Understanding instrument wear and defect formation is crucial for clinical safety and efficacy.
• Noncontact, three-dimensional optical profilometry offers a potential method for detailed surface analysis.

Purpose of the Study:

• To evaluate defects and surface changes in NiTi instruments using 3D optical profilometry.
• To compare defect propagation in Reciproc R25 and WaveOne Primary systems.
• To assess the accuracy and reliability of 3D optical profilometry for NiTi instrument analysis.

Main Methods:

• Two NiTi systems (Reciproc R25, WaveOne Primary) were analyzed before and after two instrumentation cycles.
• Surface areas (211 × 211 μm) 3 mm from the tips were examined using 3D optical profilometry.
• Quantitative analysis employed Sa, Sq, and Sz roughness parameters; statistical analysis was performed.

Main Results:

• Significant wear increase (P=0.007) observed in both groups, particularly between baseline and second cycle.
• WaveOne instruments showed significantly higher wear (Sz median values: 33.68 μm vs. 2.89 μm for Reciproc).
• Surface roughness (Sa, Sq) significantly increased (P=0.016, P=0.008) from first to second cycle, predominantly in WaveOne specimens; more defects noted qualitatively.

Conclusions:

• WaveOne Primary instruments exhibited more defects than Reciproc R25 instruments.
• Three-dimensional optical profilometry proved to be an accurate, repeatable, and reproducible method for assessing NiTi instruments.