[Study of the effect of different methods on the removal of calcium hydroxide in root canal by micro-computed tomography in vivo].

Abstract

Purpose: To establish molar root canal model with micro-computed tomography (Micro-CT) and evaluate the removal efficiency of calcium hydroxide by different methods.

Methods: Eight molar teeth (24 root canals) extracted from the Department of General Dentistry, Shanghai Ninth People's Hospital from October 2023 to February 2024 were collected. Root canal preparation was instrumented by M3 according to standard root canal treatment procedures, then calcium hydroxide was injected into the root canal. One week later, the samples were randomly divided into 3 groups according to different irrigation methods(n=8): lateral opening syringe group, ultrasonic group and sonic vibration group. Micro-CT was used to reconstruct the root canal system before and after irrigation, and independent root canals were marked with different colors. The root canals were divided into upper root segment, middle root segment and apex segment. The volume of calcium hydroxide in each canal was calculated, and the clearance rate of calcium hydroxide was compared among the groups. SPSS 19.0 software package was used for statistical analysis.

Results: None of the three methods could completely remove calcium hydroxide from the root canal. When sodium hypochlorite was used as the flushing solution, the removal effect of ultrasonic group and sonic vibration group was significantly better than that of lateral opening syringe group(P＜0.05). The removal efficiency of calcium hydroxide by ultrasonic group and sonic vibration group was similar, and the difference was not statistically significant(P＞0.05). The removal rate of calcium hydroxide in apical segment was low.

Conclusions: Micro-CT can reconstruct the molar root canal model efficiently for evaluating the removal effect of calcium hydroxide. The removal efficiency of calcium hydroxide in ultrasonic group and sonic vibration group is similar, and both are better than that in lateral syringe group.