Bone mineral content of mandibles: normal reference values--rate of age-related bone loss.

The purpose was to obtain the normal sex- and age-related reference values for the bone mineral content (BMC) in the bones of the mandible and the forearms, as estimated by dual-photon absorptiometry; to examine the effect of tooth loss on the mandibular BMC, i.e., BMC in the basal part of the mandible; and to analyze the rate of the sex- and age-related BMC loss in the mandible in normal old edentulous individuals greater than or equal to 70 years of age and its relationship to the corresponding BMC loss in the forearm bones. The following groups were measured: young dentate adults (n = 100; women (W): men (M) = 1:1), young, long-term edentulous W (n =15), and old edentulous individuals (n = 24 W, 10 M). In the old group the BMC measurements were repeated after 2- or 3-year period (n = 18 W, 10 M). The analyses indicate that the mandibular BMC reference values differ by sex and age; but correction for the state of dentition seems of minimal benefit. The average BMC loss (%) in the bones of the mandible and the forearms seems to be higher in old W (1.5 and 1.4% per year) than in old M (0.9 and 0.7% per year), but of the same magnitude in each sex. The relationship between the BMC loss (%) in the two sites was significant (P less than 0.01) but rather weak. Thus, it seems important to follow the sex- and age-related BMC loss in the mandible separately.

Premenopausal bone mineral content relates to height, weight and calcium intake during early adulthood.

The influence of dietary and anthropometric factors on bone mineral content was studied in 183 healthy premenopausal French-Canadian women aged between 40 and 50 years and living in the same area. Dietary evaluation of their calcium (Ca), caffeine and alcohol intake since the age of 20 was performed in all cases. Age, height, weight, exercise level, cigarette smoking, parity and estrogen were also recorded. Bone mineral content of the L2 to L4 vertebrae (BMCL, n = 183) and forearm (BMCF, n = 137) were measured respectively by dual and single photon absorptiometry. While stepwise regression analysis showed a significant relationship between total BMCL and height, weight and Ca intake, this only occurred with weight and Ca intake when BMCL was corrected for height of L2-L4 (BMCL/cm) or for bone scan area of L2-L4 (BMCL/cm2). BMCF expressed per unit of length correlated to height only. When subjects were divided into three groups according to their Ca intake (less than 500 mg/day, between 500 and 1000 mg/day and greater than 1000 mg/day), the mean BMC adjusted for significant covariables (height and weight) was statistically different for the low and high intake groups at both sites (BMCF, F = 3.9, P = 0.02; BMCL, F = 4.2, P less than 0.02; BMCL/cm, F = 6.1, P less than 0.005; BMCL/cm2, F = 4.4, P less than 0.02). These findings indicate that, of the variables considered, Ca intake, height and weight were the only significant factors related to bone mass in our homogeneous population. It is therefore suggested that Ca intake in early adulthood influences the axial and appendicular bone mass in premenopausal women.

In vivo measurement of bone mineral content of mandibles by dual-photon absorptiometry.

The purpose of this study was 1) to reveal the short- and long-term precision of noninvasive in vivo measurements of bone mineral content (BMC) in larger and smaller parts of mandibles and in forearm bones by a new two-dimensional dual-photon attenuation system GT45; 2) to develop normal reference values and ranges for mandibular BMC in individuals between 20-40 yr of age without known systemic diseases and with normal oral state, (n = 56, F:M = 1:1), and 3) to relate mandibular BMC with forearm bone BMC, sex and age, by comparing BMC values of a well-defined normal old test group (n = 24, F:M = 1:1, 70-81 yr of age) with the normal reference values. The analyses indicated: 1) the in vivo short- and long-term precision of the methods is high. 2) BMC of mandibles and forearm bones is significantly related to sex and age (P less than 0.01, and in mandibles of young females/males: P = 0.02). 3) BMC in mandibles and forearm bones is significantly correlated in both age groups (P less than 0.01) with relatively weak coefficients of correlation. GT45 may be used to follow BMC changes in mandibles in groups or single individuals after surgical treatment and to evaluate sex and age dependent BMC changes in mandibles and forearm bones.

Adrenal steroids, bone mineral content and endometrial pathology in postmenopausal women.

In 19 postmenopausal women, basal serum levels of cortisol, unconjugated dehydroepiandrosterone (DHA), dehydroepiandrosterone sulphate (DHAS), testosterone and unconjugated and total estrone were measured both before and during an ACTH test. A positive correlation was found both between basal levels of DHAS and the DHA response to ACTH, respectively, and trabecular bone mineral content of the distal forearm. A significant correlation was also observed between bone mineral content and precancerous/cancerous states of the uterine epithelium.

Soft-tissue fluid determination by dichromatic absorptiometry.

Dichromatic absorptiometry (DA) in a noninvasive method for individually determining the amount of lipid, bone mineral, and protein and water present in a mixture by differential attenuation of radiation beams emitted from a dual photon source. The physics involved permit these components to be determined extremely accurately and precisely. The present study investigated the ability of DA limb scans to measure changes in total body water produced in dogs and in patients. Dichromatic absorptiometry was determined to be a valid method of measuring changes in total body water content as reflected by limb fluid content changes. Precision was limited by the accuracy in positioning the limb for repeated scanning. Dichromatic absorptiometry has the potential of becoming a clinically useful instrument for measuring fluid content changes in limbs produced either by changes in total body water content or by conditions causing limb edema.