Correlation of amyloid and ameloblast-associated proteins to odontogenic cysts and tumors: A cross-sectional study.

Background and Aims: Odontogenic cysts and tumors often form hard and soft structures that resemble odontogenesis. It is well known that amyloid is produced in Pindborg tumors; however, it is still debatable whether it is also formed in other odontogenic tumors and cysts. This study aimed to detect the presence of amyloid in different odontogenic cysts and tumors in correlation to matrix proteins secreted during enamel formation; namely amelogenin and odontogenic ameloblast-associated protein. Methods: This study included formalin fixed paraffin embedded tissue blocks of 106 different types of odontogenic cysts and tumors. Congo red and thioflavin T were performed to confirm the presence of amyloid; immunohistochemistry was used to detect amelogenin and odontogenic ameloblast-associated protein. Results: Amyloid was detected in pindborg tumors (conventional), adenomatoid odontogenic tumors, odontogenic fibroma (Amyloid variant), follicular solid and unicystic ameloblastomas, radicular cysts, dentigerous cysts, dentinogenic ghost cell odontogenic tumor, ameloblastic fibroma, calcifying odontogenic cyst, and primordial Odontogenic tumor. Amelogenin was detected in 95.3% of the cases, while odontogenic ameloblast-associated protein was detected in 93.4% of the cases. The association between odontogenic ameloblast-associated protein and amyloid was highly significant at Conclusion: Although pindborg tumor is the bonafide example of amyloid deposition in odontogenic tumors, this study concluded that amyloid may be deposited in traces to massive amounts in various odontogenic cysts and tumors, and it is significantly linked to odontogenic ameloblast-associated protein but not amelogenin matrix protein, since all amyloid cases were odontogenic ameloblast associated protein positive.