Syringe Irrigation in Minimally Shaped Root Canals Using 3 Endodontic Needles: A Computational Fluid Dynamics Study

Area of Science:

• Endodontics
• Dental Materials
• Biomedical Engineering

Background:

• Effective root canal irrigation is crucial for disinfection.
• Understanding irrigant flow dynamics in curved canals is essential for treatment success.

Purpose of the Study:

• To compare irrigant flow in curved root canals prepared to different apical sizes.
• To evaluate the impact of constant-taper versus variable-taper instruments on irrigant delivery.
• To assess the effectiveness of different endodontic needles and flow rates.

Main Methods:

• Micro-computed tomographic imaging of prepared root canals (apical sizes 20, 25, 30/.06 taper).
• Computational Fluid Dynamics (CFD) modeling to simulate irrigant flow.
• Syringe irrigation simulations using 30-G open-ended, 30-G closed-ended, and 31-G closed-ended needles at 0.05 and 0.15 mL/s flow rates.

Main Results:

• Irricant penetration to working length was not achieved in canals prepared to apical size 20 or 25/.06 taper.
• A 30-G open-ended needle at a low flow rate reached working length in size 30/.06 canals but had low wall shear stress.
• A 31-G closed-ended needle at a high flow rate reached working length in size 30 canals with higher wall shear stress but also higher apical pressure.

Conclusions:

• Syringe irrigation efficacy is compromised in minimally shaped curved root canals.
• Adequate apical preparation size is critical for effective irrigant delivery.
• Needle design and flow rate influence irrigant penetration and cleaning efficiency.