Effect of antioxidant solutions on the prevention and elimination of para-chloroaniline in root canals: an in vitro study

This study aimed to evaluate the effect of different antioxidant solutions on the prevention and elimination of para-chloroaniline (PCA) in root canals when used as intermediate or final irrigants. Ninety-six bovine teeth were divided into 16 experimental groups (n = 6) according to irrigation protocols designed to mitigate PCA formation resulting from the sodium hypochlorite (NaOCl) and chlorhexidine gluconate (CHX) interaction. The antioxidant solutions sodium thiosulfate, sodium ascorbate, and proanthocyanidin were used either as intermediate irrigants with different waiting times (0, 5, 10, and 15 min) or as final irrigants. PCA was quantified in vitro using gas chromatography-mass spectrometry (GC-MS), and its prevention was visually assessed using scores. PCA formation was detected in all groups evaluated. The use of antioxidant solutions reduced PCA concentrations (0.13-1.29 mg/L) compared with the control group (8.31 mg/L). When applied as final irrigants, these solutions produced a more pronounced decrease in PCA levels compared to their use as intermediate irrigants, regardless of the waiting time. Sodium ascorbate used as the final irrigant showed the greatest effectiveness (0.13 mg/L), followed by sodium thiosulfate (0.17 mg/L) and proanthocyanidin (0.24 mg/L). Visual scoring correlated closely with GC-MS measurements. The use of investigated antioxidant solutions as intermediate or final irrigants demonstrated promising performance in the prevention and elimination of PCA in root canals.