(PR089) Comparison of Lubricant Viscosity and Time Required for Separated Rotary File Retrieval in Teeth with Curved Canals

Objective: This study compares lubricants with different viscosities used to aid in the removal of separated rotary files in teeth with curved roots. The hypothesis is there’s an ideal viscosity which will reduce the time required to remove a separated rotary file. With this understanding of viscosity of a lubricant, it can be translated to clinical practice and improve patient outcomes.

Methods: Extracted human teeth were accessed using a dental operating microscope, prepared with rotary instrumentation. The curvature of the root canals was measured by 2D-radiography, as described by Schneider. Three-millimeter Protaper-Ultimate F2 file tips were intentionally separated at the apical portion of the root canals with more than 30° curvature. Afterwards, the separated files were removed using ultrasonic activation with 5 different lubricants. Total time used for loosening of the separated file was recorded. Experimental groups include silicone oils named by their respective viscosity: 50 cSt, 100 cSt, 500 cSt, 1000 cSt and a control group: 17% EDTA. Statistical analysis was completed with an alpha level of 0.10 using linear regression in RStudio software.

Results: Fifty roots with 30° curvature or higher were recruited and evenly distributed among five groups. The time required for separated file removal was significantly higher in the 100 cSt silicone oil group compared to control (p=0.07). All other groups have no statistical differences compared with the control group (p >0.1).

Conclusion: Silicone oil is a suitable lubricant for separate rotary file removal in teeth with curved roots and differing viscosities may influence efficacy.