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Figure 2. Morphology of unerupted tooth vs. erupted tooth. (A) Longitudinal section of a rat first mandibular molar at day 3 post-natally, showing the loose connective tissue sac, the dental follicle (DF), that surrounds the 1st molar (M1). Note that the unerupted tooth is encased in alveolar bone (AB), and that a prominent stellate reticulum is present. (B) Fluorescence micrograph image of a rat maxillary first molar and adjacent tissue with 40 cN of orthodontic force for 5 days. Root (R), periodontal ligament (P), and alveolar bone at compression (C) and tension sites (T). Tetracycline bone markers (orange and yellow) have been incorporated into the alveolar bone to demonstrate the bone turnover patterns. Note that the tension side is largely osteogenic, while the compression side is marked by cratering of both the bone and root, indicating resorption; however, some of the craters are also osteogenic, indicating that remodeling is taking place.
