Comparison of EDTA- and glycolic acid-based irrigation regimens with or without chitosan for calcium hydroxide removal from artificial internal resorption cavities: an in vitro study

Complete removal of calcium hydroxide [Ca(OH) 2 ] prior to obturation is critical for optimal sealer penetration and long-term success of root canal treatment; however, its elimination from complex anatomical regions such as internal resorption cavities remains challenging. This study evaluated the effectiveness of ethylenediaminetetraacetic acid (EDTA)-and glycolic acid (GA)-based irrigation regimens with or without chitosan in removing Ca(OH) 2 from artificial internal resorption cavities. Sixty extracted human mandibular premolars were prepared, standardized artificial internal resorption cavities were created, and the specimens were filled with Ca(OH) 2 . The teeth were randomly allocated to four experimental groups (n = 15) according to the irrigation protocol: EDTA, EDTA + chitosan, GA, and GA + chitosan. Residual Ca(OH) 2 was evaluated using stereomicroscopic scoring and quantitative ImageJ analysis. For stereomicroscopic assessment, the tooth was considered the experimental unit, and the scores obtained from the two root halves of each tooth were combined to generate a tooth-level score. Data were analyzed using the Kruskal–Wallis test followed by the Dunn–Bonferroni post hoc test ( p < 0.05). Significant differences were observed among the experimental groups ( p < 0.001). The EDTA group exhibited the highest combined stereomicroscopic scores, whereas the GA + chitosan group showed the lowest scores. No statistically significant differences were observed between the EDTA and EDTA + chitosan groups or between the GA and GA + chitosan groups in the stereomicroscopic analysis. In contrast, both GA-based protocols demonstrated significantly lower residual Ca(OH) 2 than the EDTA-based protocols. Quantitative ImageJ analysis corroborated this pattern, with the GA + chitosan regimen showing the lowest percentage of residual Ca(OH) 2 surface coverage. Within the limitations of this in vitro study, GA-based irrigation regimens resulted in less residual Ca(OH) 2 than EDTA-based regimens, although the specific contribution of chitosan could not be established.