H 3-proline and tetracycline as marking agents in the study of reparative dentine formation

Abstract

W hen studying the reparative dentine following indirect pulp-capped teeth, we,l as well as otheq2* 3 assumed that the basophilic line most distant from the pulp represented the calciotraumatic line formed in response to treatment. In cases in which numerous baaophilic lines were present in the dentine, however, it was difficult to determine where the deposition of reparative dentine started. Therefore, it is necessary to mark the dentine at its initial formation, especially if accurate daily rates are of interest. Recent studies have indicated the possible use of nontoxic doses of tetracycline as marking agents for growing calcified tissue. Milch and associates,4~ 5 studying bone localization of tetracycline in rats, reported a characteristic yellowish fluorescence under the ultraviolet light at the retention sites of tetracycline in bone. Such fluorescent sites were observed in newly forming bone and in the continuously growing incisor of the rat. The effects of tetracycline on bone growth, their marking characteristics, the dosimetry, and the toxicity of these agents were studied by &all, Perkins, and Gilda, who found Terramycin a suitable agent for assessing the differential growth changes which take place in growing bones. The in vivo experiments carried out by Harcourt and colleagues,7 who administered tetracycline to growing children, demonstrated that this antibiotic agent was localized in dentine. They found that the fluorescence is associated with a typical globular pattern of calcification in dentine and eementum. Contrary to BevelanderW hypothesis of an inhibitory effect of tetracycline on skeletal growth, Harcourt. and associates7 do not believe that there is any disturbance in mineralization during the banding of dentine as a result of tetracycline therapy. Yellowish fluorescent lines were observed in the dentine of the rat molar by G&n and Johannessen .g These lines were seen to correspond to the periods of tetracycline administration.