External Root Temperature and Its Relationship With Dentin Thickness During Gutta-Percha Removal Procedures With Ultrasound. An Ex Vivo Study

Introduction

This study aims to evaluate the temperature rise on the external root surface during gutta-percha removal with 2 types of ultrasonic tips, and its relationship with the root dentin thickness.

Methods

A total of 56 single-rooted teeth were prepared for gutta-percha removal procedures, conducted for 40 seconds using 2 types of ultrasonic tips at depths of 6 mm and 11 mm. The temperature generated was measured using a type K thermocouple at 3 measurement points. Nonparametric Wilcoxon test was used, and the correlation between thickness and temperature rise was evaluated with Spearman correlation test.

Results

The temperature rise occurred in all groups, reaching maximum values of 21.0°C (mean = 14.6) with Clearsonic and 11.3°C (mean = 4.2) in the Clearsonic Black group, recorded at a 1-mm depth at 40 seconds (P < .05). At 20 seconds, the Clearsonic produced an increase ranging from 10.5°C and 12.9°C in 25% of teeth. No significant differences were observed between the 2 types of ultrasonic tips at an 11-mm depth, across all time intervals and measurement points. Spearman's coefficient showed significant correlations with Clearsonic use at 20 seconds. Significant correlations with Clearsonic Black were observed at 20 and 40 seconds at point T1.

Conclusions

The Clearsonic Black generates a smaller temperature increase at a depth of 6 mm compared to the Clearsonic and within a time not exceeding 20 seconds (P < .05). There is a partial correlation between temperature increase and dentin thickness.