Densitometric evaluation of skull and jaw bones after administration of thyroid hormones in rats

Abstract

Radiographs of the mandible can be utilized to characterize loss of bone density elsewhere. In addition this investigation indicated that optical densitometry is an inexpensive and low risk method for studying bone density.

Thyroid Hormones May Influence Cortical Bone Healing Around Titanium Implants: A Histometric Study in Rats

“…It was also shown that an imbalance in the levels of T 3 and T 4 correlated positively with the levels of the factors involved with bone homeostasis. For instance, a decrease in osteoprogenitor cells, growth factors, and cytokines, resulting in a decreased bone apposition, was reported for hypothyroidism, whereas the opposite characterizes hyperthyroidism 6,26 . In the present study, a similar trend was observed, meaning that hypothyroidism and hyperthyroidism resulted in impaired and improved bone healing, respectively.…”

“…In vitro studies showed that T 3 may act on osteoblasts to indirectly stimulate osteoclastic bone resorption 3 and may be important in switching the osteoblast phenotype from a proliferating preosteoblast form to a mature osteoblast phenotype capable of bone matrix formation 4 . Moreover, thyroid hormones were shown to regulate gene expression in osteoblastic cells 5,6 …”

“…However, it was not until the 1970s that it became apparent that thyroid‐associated metabolic bone disease had specific histologic features 8 . In rats, hyperthyroidism histologically demonstrates an increase in mineral apposition and formation rates and a small increase in the number of eroded surfaces, as well as a decrease in bone mineral density (BMD), as determined by dual energy x‐ray absorptiometry 6,7 . The consequences of hypothyroidism on histologic features and on BMD are less well documented.…”

“…Although thyroid dysfunctions may affect bone metabolism via their effect on thyroid hormone levels that influence bone turnover, 2,5,6 there is a lack of information regarding the effect of changes in T 3 and T 4 serum levels on bone healing around titanium implants. Thus, the purpose of the present study was to investigate, by histometric analysis, the effect of thyroid hormones on bone healing around titanium implants placed in the rat tibiae.…”

Effect of Simvastatin Administration on Periodontitis‐Associated Bone Loss in Ovariectomized Rats

“…The radiographic films were processed in a standard dark room in the Atomic Energy Organization of Iran, Tehran, Iran. Using a digital densitometer, ‖‖ optical density readings were made three times in a 1‐mm perimeter around each of the points described as follows: 15 1) point 1 (on the alveolar bone): superior to the BU point (a point on the premaxilla between the jaw bone and the lingual surface of the upper incisors); 2) point 2 (on the hard palate): anterior to the MU point (a point on the intersection between the maxillary bone and mesial surface of the upper first molar); 3) point 3 (on the skull): PO point (the most posterior point on the cranium); and 4) point 4 (on the mandibular bone): K point (the intersection between the gonion to menton [Go‐Mn] line and perpendicular to the Go‐Mn line through the gnation [Gn]) (Fig. 1).…”