125I Absorptiometry Research Articles

Effect of intermittent delivery of fluoride to solution on root hard-tissue de- and remineralization measured by 125I absorptiometry.

The effect of intermittent fluoride levels on root hard-tissue de- and remineralization was studied once daily for 21 days in a pH-cycling caries model with simulated fluoride clearance curves. Four root hard-tissue blocks, from each of 12 human teeth, were cut out parallel to the cementum surface. During a daily 15-hour period, the blocks were subjected 12 times to pH changes similar to those which occur in plaque after a carbohydrate intake. The fluoride was delivered immediately before a daily nine-hour remineralization period. Four experiments were independently carried out: One block from each tooth was subjected to pH-cycling without and with fluoride delivery, simulating a rinse with 0.025, 0.2, and 1.0% sodium fluoride (NaF), respectively. The mineral change in the blocks was monitored by 125I absorptiometry and expressed as the change in transmission (delta T). The surface between the data points (delta T values) and the x axis (time points) was used as a summary measure, i.e., the area under the curve (AUC). When no fluoride was delivered, the delta T increased over 21 days, indicating loss of mineral. The AUC was, on average, 5.85 +/- 0.68 (mean +/- S.E.) %.day. In the 0.025% NaF-rinse experiment, there was a marked reduction in mineral loss, indicated by an average AUC of 1.66 +/- 0.59%.day. In both the 0.2 and 1.0% NaF-rinse experiments, a decrease in delta T, indicating gain of mineral, was observed from day 2. Negative delta T values occurred after 7 and 3 days, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of constant fluoride levels in solution on root hard tissue de- and remineralization measured by 125I absorptiometry.

To study the effect of fluoride on de- and remineralization of root hard tissue, an automatic pH-cycling caries model, simulating Stephan curves, was used for 21 days. From each of 13 unexposed human roots, four cementum/dentin blocks were prepared. Four experiments were carried out: one block from each tooth as subjected to pH cycling without and with fluoride at the concentrations of 0.02 ppm (1.0 mumol/l), 0.20 ppm (10.5 mumol/l) and 2.00 ppm (105.3 mumol/l) in the de- and remineralizing solutions, respectively. Mineral change in the specimens was monitored by 125I absorptiometry. When no fluoride was added to the solutions the change in transmission (delta T) increased continuously over 21 days, indicating loss of mineral. In the 0.02-ppm F experiment, there was a marked decrease in delta T, but almost no change in the 0.20-ppm F experiment. pH cycling with 2.00 ppm F in the solutions resulted in a gain of mineral in or most likely on the surface of the cementum/dentin blocks, indicated by a continuously decreasing delta T. The fluoride level in the solution significantly influenced the change in the mineral content of the specimens. Microradiographs of the sectioned blocks showed radiodense surface zones, varying degrees of subsurface demineralization and signs of remineralization or mineral deposition.

Journal of Bone and Mineral Research

Of 118 consecutive white patients referred for asymptomatic primary hyperparathyroidism, the diagnosis was clinically confirmed in 100, of whom 85 adults had a serum calcium less than 3.0 mM (12 mg/dl) and no skeletal, rheumatic, or significant neuropsychiatric symptoms, azotemia, or other significant illnesses. Among these 85, 68 had both asymptomatic and medically uncomplicated hyperparathyroidism, whereas 17 had historical, radiographic, or ultrasonic evidence of renal stone disease. The 20% with past or present renal calculi concentrated their urine significantly better than the 68 others (p = 0.05), but these two groups were otherwise not distinguished by the tests we performed, so all 85 patients were analyzed together. Systolic and diastolic blood pressures were normal, but premature osteopenia and/or impaired renal function were present in 29-36% of the patients. Micrometer measurements of metacarpal radiographs and 125I photon absorptiometry at the shaft of the radius revealed cortical osteopenia. Osteopenia was equally significant in the distal radius (cortical plus trabecular bone). These quantitative measurements were superior to routine bone radiography, and ROC analysis showed that 125I absorptiometry at either site was superior (p less than 0.01) to metacarpal cortex measurements for detecting premature osteopenia, which was present in more than a third of these patients. Creatinine clearances (24 h) and maximum urine concentrating capacity (overnight dehydration plus the synthetic vasopressin analog DDAVP) were each significantly reduced, despite all patients' normal BUN and serum creatinine levels. Sequential performance of a 24 h creatinine clearance and a urine concentration test revealed abnormalities in the renal function of 27 of 74 patients (36%), with a specificity of 95% and a higher sensitivity than either test alone (27-29%).(ABSTRACT TRUNCATED AT 250 WORDS)

Root Hard-tissue Demineralization Rate Measured by 125I Absorptiometry: Comparison with Lesion-depth Measurements

The aim of the present study was to compare demineralization of root hard tissue, monitored by 125I absorptiometry, with lesion-depth measurements under polarized light microscopy. The intact roots of ten human molars, which had not been exposed to the oral environment, were divided into 39 cementum/dentin blocks and exposed to a buffer solution of pH 4.5 containing 2.2 mmol/L calcium and inorganic phosphate. After demineralization for 3.5, 7, 14, and 21 days, transmission measurements by 125I absorptiometry were performed, and one block from each tooth was taken out of the solution for lesion-depth measurement. The results showed a high degree of correlation (r = 0.952) between lesion depth and change in transmission, with a more rapid increase initially in both variables. A linear relationship with the square root of time was found. Conversion of transmission data to lesion-depth data was possible when this caries model system was used on cementum dentin blocks.

Estrogen/gestagen therapy changes soft tissue body composition in postmenopausal women

The long-term effect of percutaneous and oral estrogen replacement therapy on soft tissue body composition was examined in a two-year, placebo-controlled study with 110 early postmenopausal women. The women were allocated to four treatment groups: (1) oral cyclical combination of estradiol valerate and cyproterone acetate, (2) oral placebo, (3) percutaneous 17β-estradiol, supplemented by oral progesterone during the second year, or (4) percutaneous placebo cream. Total-body lean body mass (LBM) and fat mass (FM) were measured by dual photon ( 153Gd) absoptiometry once a year, and the fat layer in the distal forearm (FAT arm) was measured every 3 months by single photon ( 125I) absorptiometry. Both hormone therapies prevented an increase in FAT arm, as observed in the placebo groups. A similar pattern was seen for FM, body weight, and skin-fold thickness (measured once a year by mechanical calipers), whereas LBM was unaffected by the therapy. Hormonal replacement therapy prevents the age-related increase in body fat observed after the menopause.

Measurement of the subcutaneous fat in the distal forearm by single photon absorptiometry

The influence of subcutaneous fat on single photon ( 125I) absorptiometry (SPA) measurement of bone mineral content of the distal forearm was investigated. A fat correction model was tested by measurements on eight lean subjects with different amounts of porcine fat around their forearm, and further validated from measurements on 128 females. In addition, it is shown that the fat content in the distal forearm can be measured by SPA with a short-term precision at 1.9% in an obese subject and that it correlates well with total body fat ( r 2 = .7) measured by dual photon absorptiometry, skinfold thickness ( r 2 = .5), and body mass index ( r 2 = .6). By using this method in a double-blind placebo-controlled trial, hormonal substitutional therapy significantly decreased the forearm fat content without affecting the body weight in postmenopausal osteoporotic women.

Estimation of total body composition from single photon absorptiometry measurement of forearm fat content

The forearm fat content (FATarm, measured by single photon (125I) absorptiometry) and the 24-h urinary creatinine excretion (24 Ucrea) were determined in 29 healthy adults (12 males and 17 females), whose total body fat percentage was measured by three different methods: (i) Dual photon (153Gd) absorptiometry (DPA); (ii) body density measurements (BD); and (iii) total body potassium determinations (TBP). Lean body mass (by DPA, BD, and TBP) correlated significantly with 24 Ucrea (r = 0.87-0.89, standard error of estimate (SEE) = 5.2-6.3 kg). The total body fat percentage could be predicted from FATarm with SEEs at 3.4-5.8 (r = 0.85-0.88) and from 24 Ucrea + body weight with SEEs at 5.1-7.5 (r = 0.61-0.72). We conclude that the FATarm measurement represents a new tool for simple assessment of body composition on a group basis.

Subtraction radiography for the diagnosis of periapical bone lesions.

Abstract Subtraction and conventional radiography were evaluated for the diagnostic potential to assess periapical bone lesions. The periapical region of dry human mandibles was radio‐graphically examined, subjectively evaluated and measured by 125I absorptiometry before and after the creation of bone defects. Both conventional radiographs and subtraction images made from the conventional radiographs after digitization were interpreted by 10 dentists. Receiver operating characteristic (ROC) analysis technique was used to compare the two techniques. There was a higher diagnostic accuracy using subtraction technique. For a lesion depth corresponding to < 2 mm of compact bone, there was a clear difference between the techniques, but for deeper lesions the conventional technique gained force. The subtraction technique was significantly superior for lesions confined to cancellous bone. The statistical difference in the diagnostic utility of subtraction compared with conventional technique was found to be less for lesions of the cortical bone. Therefore, the conclusion is that subtraction radiography improves the detection of small lesions in the periapical bone area.

Representativity of regional to total bone mineral in healthy subjects and 'anticonvulsive treated' epileptic patients. Measurements by single and dual photon absorptiometry.

Dual photon (153Gd) and single photon (125I) absorptiometry were used to measure the regional bone mineral content (BMC) and density (BMD), as well as the total body mineral content (TBBM) and density (TBBD), in sixty-nine healthy subjects and in twenty-three epileptics on phenobarbitone. The BMCs (and BMDs) of all regions were significantly correlated to each other and to the TBBM (and TBBD). No difference in the ability to discriminate between the different study groups was found for the various regions, excepting the BMD of the head. The relationship between the forearm BMC and TBBM was highly significant, and identical in the five groups. The relationships between spinal BMC and forearm BMC, and TBBM differed in the five groups. It is concluded that some local measurement may be used as estimates of the total body bone mineral in some groups of patients with minor metabolic bone disease and healthy subjects.

Bone mineral and vitamin D in Aleutian Islanders

Serum concentrations of vitamin D metabolites (chromatography) and bone mineral status (125I absorptiometry) were examined in a group of Aleutian Islanders age 40-75 from St Paul Island, Alaska. Based on 25-(OH)D (16.6 ng/ml) vitamin D status appeared adequate. However, high concentrations of 1,25-(OH)2D (44.3 pg/ml) and very low concentrations of 24,25-(OH)2D3 (0.6 ng/ml) were found. Among females, low bone mineral levels were associated with high concentrations of 1,25-(OH)2D. A low calcium intake in these Aleutians may be responsible for high concentrations of 1,25-(OH)2D and resorption of calcium from bone.

Techniques for assessing alveolar bone mass changes in periodontal disease with emphasis on 125I absorptiometry.

No practical methods are presently available for measurement of alveolar bone activity at one instant of time. However, roentgenological methods making measurements at 2 different times can be used to assess alveolar bone activity. The most sensitive, specific and accurate method for this purpose presently in use is 125I absorptiometry. This method has the further advantage of giving the patient minimal radiation exposure. New methodology is under development which obviates the need for fixed geometry and could provide a 3-dimensional image of alveolar bone.

Experimental alveolar bone loss in the monkey evaluated by 125I absorptiometry.

An 125I absorptiometry technique is described which has sufficient precision to detect the alveolar bone loss associated with ligature-related periodontitis in the monkey. Six monkeys had significant drops in alveolar bone mass 14 days after the the application of a silk ligature around the gingival margin of an adjacent tooth. Variation in the magnitude of bone loss was observed. These may represent variations in the pathogenicity of the microflora produced in response to a ligature and/or variation in host response to the insult produced by specific dental plaque organisms. The lack of bone loss post-ligature plus antibiotic therapy supports the theory that the bacterial-host interaction, not simply irritation from the ligature alone, is responsible for the bone loss. The potential for bone regeneration after ligature-induced bone loss is demonstrated.