[Evaluation of the efficacy of 70% ethanol in removing calcium hydroxide in curved root canals]

To evaluate the efficacy of micro-computed tomography(Micro-CT) in removing calcium hydroxide from posterior curved root canals.

Twenty molar teeth (48 root canals) extracted at the Department of General Dentistry, Shanghai Ninth People's Hospital between December 2023 and February 2024 were collected. After preparing by Ni-TI instruments M3 according to standard root canal treatment procedures, calcium hydroxide was injected into the root canals. One week later, the samples were randomly divided into 6 groups(n=8) based on different irrigation methods: sodium hypochlorite group, 17% EDTA group and 70% ethanol group. Each group was further divided into 2 subgroups with or without sonic vibration. Micro-CT was used to reconstruct the root canal system before and after irrigation, with independent root canals marked using different colors. The root canals were categorized as upper segment, middle segment, and apical segment. The volume of calcium hydroxide in each segment was calculated, and the clearance rate of calcium hydroxide in each segment was compared. SPSS 19.0 software package was used for statistical analysis.

Calcium hydroxide could not be completely removed from any of the 6 groups tested. The removal efficiency of calcium hydroxide by ethanol in the apical region was higher than that achieved by other two groups(P＜0.05). In the ethanol subgroup, there was no significant difference in removal efficiency between sonic vibration and syringe techniques(P＞0.05).

Using 70% ethanol enhances the removal efficiency of calcium hydroxide in curved root canal.