Collagen and Its Role in predicting the Biological Behavior of Odontogenic Lesions

Odontogenic cysts and tumors have variable recurrence rates. Recurrence rate is mainly due to the activity of the epithelium. The epithelium of these lesions has been investigated extensively in regard to their role in proliferative and aggressive behavior of the lesions. However, the role of the connective tissue wall in their behavior has not been studied as extensively. Collagen is an essential part of the connective tissue as a whole and fibrous wall of cystic lesions especially. It is demonstrated by picrosirius red dye staining combined with polarization microscopy. This method permits the evaluation of the nature of the collagen fibers in addition to their thickness.

A total of 56 histopathologically diagnosed cases comprising odontogenic follicle, dentigerous cyst, unicystic ameloblastoma, keratocystic odontogenic tumor (KCOT), multicystic/solid ameloblastoma, and ameloblastic carcinoma were taken and stained using picrosirius red stain and evaluated using a polarizing microscope.

Collagen fibers in odontogenic follicles and dentiger-ous cysts showed predominant orange-red birefringence; fibers in unicystic ameloblastoma and KCOT showed both orange red and greenish-yellow birefringence; and fibers of multicystic/ solid ameloblastoma showed predominant greenish-yellow birefringence and ameloblastic carcinoma that showed almost complete greenish birefringence. As the biological behavior of the lesions in the spectrum studied progress toward aggressive nature, increase in immature collagen fibers is noticed.

This study suggests that the nature of collagen fibers plays a pivotal role in predicting the biological behavior of odontogenic lesions.

Aggressive nature of the odontogenic lesions is determined by both the epithelium and the connective tissue components (collagen). Studying the nature and type of collagen helps in predicting its biological behavior.