According to recent scientific literature, it seems that the occurence of a primary intra-osseous squamous cell carcinoma arising from degenerated odontogenic cysts is around 0.3 to 3% of cases. (Jain et al. 2013)

This malignant degeneration seems to occur more frequently in large old cysts, which have gone untreated for several years.

It seems that the only way to ensure proper diagnosis is through systematic histopathological analysis of "suspect" cysts. On that matter, follow up is paramount.