MICRORADIOGRAPHIC ASPECTS OF THE GROWING MANDIBULAR BODY DURING PERMANENT PREMOLAR ERUPTION IN THE DOG

In order to explore the bony changes in the mandibular body during pre functional intraosseous eruption of premolars, 18 dogs aged from 8 to 16 wk al the beginning of experimental period, were given two intraper itoneal injections of oxytetracycline (50 mg/kg and 35 mg/kg 2 wk late r) and 2 wk later a final injection of Alizarin red S (70 mg/kg). Micr oradiographic and fluorescent light microscopy studies showed that cha nges of the alveolar bony crypt walls were influenced by the growing d ental germs which they surrounded. The cervical volumetric reduction, which indicates the end of crown formation, induced the apposition of lamellar and then woven bone on the adjacent alveolar walls. Furthermo re, with occlusal displacement of the dental crown, the space below th e tooth was immediately filled with woven bone trabeculae and chondroi d tissue. The same phenomenon was observed. at the level of the alveol ar base, when the speed of tooth eruption was greater than that of roo t growth. During premolar development: the changes in the dental germ produces accommodating changes in the adjacent alveolar bone walls, an d mandibular transversal growth has the same characteristics as that o f a growing diaphysis.