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 de ntal follicle, a loose connective tissue sac that surrounds each tooth. Thi s bone resorption involves the follicle in that mononuclear cells enter the follicle to form osteoclasts which resorb bane to form the eruption pathwa y. In the rat first mandibular molar, probable eruption genes, CSF-1, c-fos , NF kappa B and MCP-1, are expressed maximally in the dental follicle at d ay 3 postnatally. This correlates with the time of peak influx of mononucle ar cells into the follicle. In the mouse, the first peak influx of mononucl ear cells into the first mandibular molar is at day 5 postnatally, and this study demonstrates that all four of the above resorption molecules are max imally expressed at this time in the dental follicle. Thus, this work sugge sts that these molecules may play a role in the cellular events of eruption (mononuclear cell influx and osteoclast formation) in the mouse molar at d ay 5 postnatally just as they do at day 3 in the rat molar. These results p rovide a standard for future studies on eruption in the mouse molar and ext ends the number of species in which putative eruption molecules are express ed at a critical time of eruption.