SMAD2/3 Phosphorylation is correlated with matrix metalloproteinase 9 expression in human periapical lesions.

OBJECTIVE: The aim of this study was to investigate the presence of phosphorylated SMAD2/3 (P-SMAD2/3) in periapical lesions in humans and its possible correlation with matrix metalloproteinase 9 (MMP9) during the development of apical periodontitis. DESIGN: In this study, a total of 38 samples were collected, consisting of 16 healthy controls and 22 periapical lesions. These samples underwent fixation, dehydration, and embedding for further histologic and immunochemical analysis. The expression of phosphorylated SMAD2/3 and MMP9 was quantified using the average integrated optical density. Additionally, immunofluorescence analysis was conducted to investigate the colocalization of phosphorylated SMAD2/3 and MMP9. RESULTS: The study found that periapical lesions exhibited a stronger expression of MMP9 compared to healthy controls. Additionally, the expression of phosphorylated SMAD2/3 was observed to increase in the periapical granulomas and radicular cysts group, as compared to the normal group (P < 0.01). The results of the immunofluorescence test showed that phosphorylated SMAD2/3 was colocalized with MMP9. CONCLUSIONS: The study found that SMAD2/3 phosphorylation is correlated with matrix metalloproteinase 9 expression in human periapical lesions, suggesting its potential involvement in tissue destruction and immune cell infiltration in periapical lesions.