Temperature changes during ultrasonic irrigation with different inserts and modes of activation

Area of Science:

• Endodontics
• Biomaterials Science
• Dental Materials

Background:

• Passive ultrasonic irrigation (PUI) is a common endodontic technique.
• Understanding temperature changes during PUI is crucial for procedural safety and efficacy.
• The delivery method of irrigants may influence temperature modulation during ultrasonic activation.

Purpose of the Study:

• To evaluate and compare temperature variations in root canals during passive ultrasonic irrigation under different irrigant delivery methods.
• To assess the impact of various ultrasonic instrument types (NiTi and stainless steel K-files) and sizes on irrigant temperature.

Main Methods:

• Extracted maxillary canines were instrumented to size #45.
• Thermocouples measured temperatures at 3, 6, and 9 mm from the apex.
• Two groups were tested: continuous irrigant flow (Group 1) and pre-deposited irrigant (Group 2).
• Ultrasonic activation was performed using noncutting NiTi inserts or stainless steel K-files (#15, #25, #35).

Main Results:

• Continuous flow (Group 1) resulted in initial temperature drops and temperatures near baseline, with lower readings in the coronal third.
• Pre-deposited irrigants (Group 2) showed significant temperature rises (up to 7.7°C in the coronal third).
• Larger K-files (#35) and NiTi inserts generated higher temperature increases compared to smaller K-files (#15).
• Continuous flow negated the heating potential of ultrasonic activation.

Conclusions:

• Continuous irrigant flow during PUI minimizes temperature increases, potentially enhancing safety.
• Pre-depositing irrigants and using larger instruments (NiTi or stainless steel K-files) can significantly elevate irrigant temperature.
• Instrument type and size influence the degree of irrigant warming during ultrasonic activation when irrigants are pre-deposited.