Myofibroblasts and increased angiogenesis contribute to periapical cystic injury containment and repair.

BACKGROUND: Myofibroblasts (MF) and angiogenesis are important factors in the development and expansion of cystic lesions, where these cells secrete growth factors and proteases, stimulating angiogenesis, matrix deposition and cell migration, affecting the growth of these periapicopathies. The present study aimed to evaluate the immunohistochemical expression of CD34 and α-SMA in radicular cysts (RC) and residual radicular cysts (RRC), with the purpose of contributing to a better understanding of the expansion and progression of these periapical lesions. MATERIAL AND METHODS: The present study os a descriptive, quantitative and comparative analysis of positive CD34 and α-SMA immunohistochemical expressions in 30 RC and 30 RRC specimens. α-SMA expression was evaluated in the fibrous capsule of the lesions, at 100x magnification below the epithelial lining. A total of 10 higher immunostaining fields were selected and subsequently, positive cells were quantified at 400x magnification, averaged per field. Regarding the angiogenic index, immuno-labeled microvessel counts for the anti-CD34 antibody were performed in 10 fields at 200x magnification. RESULTS: Statistically significant differences regarding α-SMA immunostaining were observed (p = 0.035), as well as a correlation between α-SMA versus CD34 (p = 0.004) in RRC. However, the angiogenic index obtained by immunostaining for CD34 indicated no statistical difference between lesions. Intense inflammatory infiltrates were predominant in RC, while mild and moderate degrees were more commonly observed in RRC (p <0.001). Intense inflammatory infiltrates were also more often noted in larger RRC (p = 0.041). Inflammatory infiltrates showed no significant correlation with α-SMA and CD34 immunostaining. CONCLUSIONS: The results indicate that the significant correlation found between the presence of MF and the angiogenic index are related to the repair process in RRC.

Immunoexpression of tryptase-positive mast cells in periapical granulomas and radicular cysts.

AIM: To evaluate and compare the immunoexpression of tryptase in samples of periapical granulomas (PGs) and radicular cysts (RCs) correlating it with the type of lesion, localization, intensity of the inflammatory infiltrate and thickness of the cystic epithelial lining, in order to gain insight into the phlogistic role of these cells in the lesions studied. METHODOLOGY: Twenty-five PGs and twenty-five RCs obtained from human teeth without endodontic treatment were submitted to morphological and immunohistochemical analysis using anti-tryptase antibody. Mast cells were identified and counted in three regions: intra-epithelial, central/superficial and deep portions. The data were analysed using the Mann-Whitney U-test (P < 0.05). RESULTS: In comparison with RCs, PGs exhibited higher immunoexpression of tryptase-positive mast cells located in both central/superficial and deep regions (P < 0.001 and P < 0.001, respectively). When considering the total number of mast cells and disregarding the location, the number of tryptase-positive mast cells increased gradually from RCs to PGs (P < 0.001). Lesions with inflammatory infiltrate grade III had greater number of tryptase-positive mast cells located in both central/superficial and deep regions than lesions with inflammatory infiltrates grade II (P = 0.045 and P = 0.025). When the location was ignored, the lesions with inflammatory infiltrate grade III also exhibited higher immunostaining of tryptase-positive mast cells (P = 0.01). CONCLUSIONS: Tryptase-positive mast cells were present in chronic periapical lesions in a larger number in periapical granulomas than in radicular cysts, in both central/superficial and deep regions.