The exploration of mechanisms of tooth eruption has been thoroughly discussed in literature, however, the ones for post-emergent tooth eruption haven't yet. In this study we have hypothesized that the driving force of this event lies in the Periodontal ligament. Young male Wistar rats were used, so that their first molar PDL can be analyzed by RNA extraction. The conditions set were to compare between: a) gene expression of individuals whose molar antagonists were ground and those whose molar antagonists were not and b) gene expression of individuals who were sacrificed three and fifteen days after antagonist grinding. Our results demonstrated that among young individuals there were statistically significant differences between opposed and unopposed teeth compared to the control group. Genes having statistically significant differences in their gene expressions among opposed and unopposed teeth were found to be involved in: bone formation, blood vessel formation, fibroblast differentiation as well as extracellular matrix remodeling. We found 7 genes that may be involved in the post-emergent tooth eruption process: adamts-18, panx3, tnmd, pth1r, p4ha3, postnand ostn. We concluded that there are, as hypothesized, statistically significant differences in the gene expression patterns between opposed teeth and teeth whose antagonists were ground. Further studies could include the analysis of gene expression patterns in adult animals, as well as the conduction of a study comparing the pathways involved in tooth eruption and post-emergent tooth eruption.