The Effect of Inflammation on Collagen Birefringence in Odontogenic Keratocyst

Objectives: To investigate the effect of inflammation in the odontogenic keratocyst wall on the polarization colors of Picrosirius red-stained collagen fibers. Methods: 50 cases of odontogenic keratocysts were studied. From each case, two 5-µm sections were cut and stained with hematoxylin and eosin and with modified Picrosirius red procedure (PSR). Cases were separated into two groups according to the inflammatory intensity: Group A- mild-to-moderate, and Group B- intense. PSR-stained sections were examined with polarizing microscope. The polarization colors of the collagen fibers were recorded separately for thick and thin fibers, and the data compared with the inflammatory intensity for each case. Results: Groups A and B included 66% and 34% of the cases, respectively. Polarization colors of the thin fibers were in the green- to- yellow spectrum, without significant differences between the groups. Polarization colors of the thick fibers significantly differ between the groups. In Group B, the frequency of thick fibers with green birefringence decreased significantly, whereas fibers with red polarization colors increased in frequency (4.6% and 44%, respectively) compared with Group A (12.3% and 23.6%, respectively). Conclusions: Inflammation has an impact on the packing of collagen fibers in the connective tissue wall of odontogenic keratocysts, reflected in their birefringence colors under polarized light. In the presence of dense inflammation, the percentage of thick fibers with green birefringence decreases, with an increase in thick fibers with red birefringence which appeared more packed.