The change of periapical exudate prostaglandin E₂ levels during root canal treatment

We have previously demonstrated that detectable levels of prostaglandin E₂ exist in periapical exudates (PE-PGE₂) from root canals of periapical periodontitis. Our data from a cross-sectional study also suggested the association of PE-PGE₂ concentrations with the active phase of periapical lesions. The objective of this study was to investigate the longitudinal changes of PE-PGE₂ levels during root canal treatment. Periapical exudate specimens were quantitatively sampled from root canals of 20 nonvital teeth at consecutive treatment visits to measure PGE₂ concentrations. The mean PE-PGE₂ levels significantly decreased following the endodontic therapy (158.0 ± 54.1 pg/μl in the first samples versus 48.4 ± 37.9 pg/μl in the second samples). A significant correlation was also found between the changes in PE-PGE₂ levels and the clinical disease expression of periapical periodontitis (p < 0.01). Decreased PGE₂ production is considered to reflect the remission of disease activity. These results suggest the central roles of PGE₂ in regulatory mechanisms for the expression of periapical disease.