Efecto del ultrasonido endodóntico sobre clorhexidina al 2% en la formación de paracloroanilina. Estudio in vitro

Introduction

Chlorhexidine (CHX) in aqueous solution is hydrolysed to p-chloroaniline (PCA), a process accelerated by increasing temperature and pH. Using endodontic ultrasound based on oscillation phenomena, cavitation, and acoustic microstreaming generates heat, affecting the CHX.

Objective

The aim of this in vitro study was to identify and quantify the physical-chemical changes, temperature and pH, and the amount of PCA formed by increasing the temperature of 2% CHX by endodontic ultrasound.

Materials and methods

Samples of 2% CHX were activated for 30, 60, 90, and 120 seconds with endodontic ultrasound 24,500 Hz. The pH and temperature were measured before and after activation, as well as the formation and amount of PCA, by reading and recording the result obtained from a standard calibration curve reading at 375 nm in a UV-visible light spectrophotometer.

Results

Independent of time, ultrasound increased the temperature of 2% CHX by 1 °C and acidified the solution. No significant changes were recorded in pH and temperature. No staining or precipitates were observed in samples ultrasonically activated at different times. Samples read at 375 nm showed no measurable PCA values. Absorption spectra of 2% CHX and 2% CHX activated for more than 60 seconds showed different spectral curves, peaks, and absorbance values.

Conclusions

Ultrasound increased the temperature and acidified the solution of CHX for all application times. No PCA was detected by visible spectrophotometry. Absorption spectra of 2% CHX activated with ultrasound at different times differs from 2% CHX without activation.

These differences indicate degradation of CHX and possible presence of PCA.