Gene expression of potential tooth eruption molecules in the dental follicle of the mouse.

Tooth eruption requires alveolar bone resorption and the presence of the dental follicle, a loose connective tissue sac that surrounds each tooth. This bone resorption involves the follicle in that mononuclear cells enter the follicle to form osteoclasts which resorb bone to form the eruption pathway. In the rat first mandibular molar, probable eruption genes, CSF-1, c-fos, NFkappaB and MCP-1, are expressed maximally in the dental follicle at day 3 postnatally. This correlates with the time of peak influx of mononuclear cells into the follicle. In the mouse, the first peak influx of mononuclear cells into the first mandibular molar is at day 5 postnatally, and this study demonstrates that all four of the above resorption molecules are maximally expressed at this time in the dental follicle. Thus, this work suggests that these molecules may play a role in the cellular events of eruption (mononuclear cell influx and osteoclast formation) in the mouse molar at day 5 postnatally just as they do at day 3 in the rat molar. These results provide a standard for future studies on eruption in the mouse molar and extends the number of species in which putative eruption molecules are expressed at a critical time of eruption.