(PR29) Plastic Deformation Associated with Simulated Usage of ProFile Vortex Blue Nickel-titanium Endodontic Files

Abstract:

Objectives: Nickel-Titanium (NiTi) rotary instruments deformation and facture can occur during root canal treatment; however, susceptibility to fracture vary with torsional stress. The objective of this study is to evaluate Vortex Blue (VB) NiTi rotary (Dentsply Sirona, Charlotte, NC) instruments changes in tip diameter at D1, length and helical angle (HA) at D2, D8, and D14 in as-received condition and after simulated-uses.

Methods: VB NiTi rotary instruments 25mm length file set of sizes 25/04, 30/04 and 35/04 were selected for evaluation (N=10/size). Simulated root canals (30-degree curvature) EndoVu training blocs (Kerr Corp., Brea, CA) were prepared to the working length to size 35/04. Each set of files were subjected to either one-two-three blocs under simulated clinical conditions. Images of as-received, 1- 2 and 3-use files were recorded using a Wild M7 Stereoscope (Leica Microsystems, Buffalo Grove, IL) and a Dino-Lite Digital camera (Torrance, CA). Tip-diameter, file length, and HA at 2mm, 8mm, and 14mm were measured for dimensional changes between groups. Statistical analysis was done using T-test (p= < 0.05).

Results: No statistical difference in VB NiTi 35/.04 and 25/.04 groups. However, 30/.04 significant changes noted at 12 mm compared to the as-received files. No significant differences in length noted.

Conclusions: The results of this study indicate that smaller size instruments are more flexible and have less plastic deformation whereas large size instruments tend to have more plastic deformation away from the tip region. As the file size increase the potential fracture site distance increases from the tip.