Apical pressures developed by needles for canal irrigation

Area of Science:

• Endodontics
• Dental Materials Science

Background:

• Pressurized air is used for drying instrumented root canals.
• Potential risks include patient morbidity and fatality.
• Low-pressure and side-vented needles are proposed safety measures.

Purpose of the Study:

• To investigate apical pressures generated by different needles during root canal drying.
• To assess the influence of needle insertion depth and canal characteristics on apical pressure.
• To evaluate the safety of low-pressure (5 psi) air injection techniques.

Main Methods:

• Apical pressures were recorded using various needles inserted into small, round, and ovoid canals.
• Low-pressure (5 psi) air was injected after each instrumentation step.
• Needle binding, withdrawal, size, design, and canal shape were varied.

Main Results:

• Apical pressures showed significant variability within tested groups.
• Tightly bound needles resulted in higher pressures compared to slightly withdrawn needles.
• Pressures increased as canals were instrumented to size 30 and larger.
• When needles were slightly withdrawn, larger bore needles produced higher pressures.

Conclusions:

• Needle binding and canal instrumentation size significantly impact apical pressure.
• Needle design and canal shape had less impact when needles were tightly bound.
• Clinical use of pressurized air for canal drying requires significant caution.