Distribution of injected dexamethasone from the buccal vestibule of the rat mandible.

Thirty-six Sprague-Dawley rats were divided into three groups of 12. Group 1 was a control, whereas group 2 had the dental pulp of the first mandibular molar acutely exposed, and group 3 had dental pulp exposure for 10 days. All animals were injected with 125I-labeled dexamethasone phosphate into the right mandibular vestibule. Each group of 12 was divided into subgroups of 4 and sacrificed at 1, 2, or 4 h. The soft tissue on the buccal side and the mandible with the molars were collected and the radioactivity determined. Dexamethasone was absorbed from the injection site and distributed to the ipsilateral mandible and to the contralateral muscle and bone similarly, regardless of the treatment. Results also indicate a possible osseous affinity for this steroid, which could be beneficial in relieving the pain of intraosseous endodontic flare-ups.