L-triiodothyronine induced hyperthyroidism in the guinea pig: a study of its effects on the periodontium

Abstract

Young adult guinea pigs were made hyperthyroid over a period of five weeks by daily injection of 3, 5, 31 triiodothyronine. To prevent the possibility of concomitant scorbutic changes during this period, the animals were kept on an ascorbic acid free diet and a daily injection of ascorbic acid allowed known adequate supplementation. Animals were sacrificed weekly for histology, first having perfused the microcirculation with Gunther-Wagner Biologica I ink. A documentation of the changes in the periodontium of the continually erupting mandibular incisor with spec ia I note of changes in the periodontal ligament microcirculation was pursued. Concomitant changes in the endochondral bone formation in the long bones was documented. In the periodontium, osteoblastic and odontoblastic integrity were not interfered with, possibly due to the prevention of scorbutic changes. In the later stages of the project, an osteoporosis of supporting bone of the periodontium, an increased resorptive activity of alveolar bone, a lesser collagenation of the periodontal ligament on the alveolar side, a vasodilation and leakage of the carbonsuspension perfusion from the ligament vessels were constant findings. Cessation of endochondral bone formation of the epiphyseal plate. of the humerus was evident as early as two weeks into the study.