The involvement of Platelet-derived growth factor-A in the course of apical periodontitis

Abstract

To investigate the expression of platelet-derived growth factor-A (PDGF-A) in the course of apical periodontitis induced in rats and to explore its possible role in the development of periapical lesions. Apical periodontitis was induced in SD rats by exposing the pulp of mandibular first molars to the oral environment for 0-42 days. Animals were killed at 0, 7, 14, 21, 28 and 42 days after lesion induction. The development of periapical lesions was investigated by radiographic and histochemical examination. Changes in the level and distribution of PDGF-A in the periapical tissue were examined by immunohistochemistry. The radiographs were scanned to a computer, and the areas of periapical lesions were calculated. Osteoclasts and PDGF-A-positive cells were counted in five randomly selected areas in each specimen. The data were then analysed by one-way ANOVA using the SPSS 13.0 statistical package. The lesions expanded from day 0 to day 21 and stabilized thereafter. PDGF-A-positive cells were observed in the periapical tissue from 7 day postoperatively. Between 7 and 21 days, when expansion of the periapical lesion was most evident, numerous PDGF-A-positive cells were found in the periapical tissue. The number of these cells showed further increases at 28 and 42 days postoperatively. Many of the PDGF-A-positive cells were inflammatory cells with different morphologies. The variation tendency of the number of PDGF-A-positive cells per high-power field was similar to that areas of the periapical lesions. Platelet-derived growth factor-A might be involved in the development of periapical lesions.