[In vitro study on bone resorption of odontogenic cysts and ameloblastomas]

To investigate the effect of bone resorption by odontogenic cysts and ameloblastomas in vitro.

Fragments of odontogenic cysts (14 odontogenic keratocysts, 6 inflamed odontogenic keratocysts, 5 dentigerous cysts) and ameloblastomas (n = 7) were incubated in vitro for 24 h. The supernatant was then removed into the culture system of SD rat calvaria. After incubation (48 h), the calcium contents of the media were measured by atom spectrophotometer. The supernatant of odontogenic cysts and ameloblastomas was measured for the bone resorption related factors such as IL-6, TNF-alpha, PGE(2), bone Gla-containing protein (BGP) and calcitonin (CT) by a radioimmunoassay system.

The calcium released in the calvaria culture media by all the odontogenic lesions was significantly higher than that in the blank controls (P < 0.01). The inflamed odontogenic keratocyst group had a significantly higher calcium concentration than odontogenic keratocyst and ameloblastoma groups (P < 0.05). In addition, the concentration of IL-6, TNF-alpha, PGE(2) and CT in the culture media of all odontogenic lesions were significantly higher than that of the blank controls (P < 0.05). IL-6 concentration in the inflamed and non-inflamed odontogenic keratocyst groups were significantly higher than that of ameloblastoma group (P < 0.05). CT concentration in the inflamed odontogenic keratocyst was significantly higher than those of odontogenic keratocyst and dentigerous cyst groups (P < 0.05). Correlation and regression analysis showed that IL-6 was significantly correlated with the calcium content (P < 0.01).

The odontogenic lesions could promote bone resorption in vitro and it is likely to be related to some of the cytokines secreted by the lesions.