Mandibular Bone Mineral Content Research Articles

The effects of dietary restriction on humeral and mandibular bone in SENCAR, C57BL/6, and DBA/2 mice

Dietary restriction (DR) increases the life span and retards the development of age-related disorders. However, the low body mass that accompanies DR is associated with risk factors for fracture that may outweigh the beneficial effects of DR on cellular aging that are mediated, in part, by limiting free radical generation and oxidative damage. We tested the effects of DR in murine models that differ in free radical generation capacity (SENCAR > C57 > DBA). Male mice of each strain were killed at 10 weeks of age (t 0; time zero) or randomized to an ad libitum-fed (AL-fed) or 30% DR feeding regimen for 6 months. The food consumption of AL-fed mice was measured daily. DR mice received 70% of the amount of food consumed by their respective AL-fed mice the previous day. The DR diet was normalized with respect to calcium (Ca), phosphorus (P), and micronutrients. Lean body mass (LBM), bone mineral density (BMD), and bone mineral content (BMC) in the humerus and mandible were determined by PIXImus densitometry. The length and midshaft width of the humerus were determined by direct measurement. There were highly strain- and diet/time-dependent effects on LBM, humerus length, mandibular and humeral BMD, and humeral BMC. The interaction between diet/time and strain was more significant in the humerus than the mandible. All 30% DR mice had lower humeral BMDs and BMCs than their respective AL-fed controls. However, 30% DR C57 and DBA (but not SENCAR) mice had higher humeral BMD and BMC than their respective t 0 controls. There was a linear relationship between LBM and humeral BMD and BMC in both AL-fed and 30% DR mice, suggesting that the lower BMD and BMC in 30% DR mice, relative to AL-fed controls, reflects a physiologic adaptation to lower biomechanical loading. Mandibular BMC in 30% DR C57 (but not DBA or SENCAR) mice was lower than that observed in their AL-fed controls. Mandibular BMD and BMC increased versus t 0 values in 30% DR mice of all strains.

Implant‐supported overdentures, a prevention of bone loss in edentulous mandibles?

The purpose of this study were to analyse 1) the changes in the bone mineral content (BMC) in mandibles with implant-supported overdentures when compared with the physiologic age-related mandibular BMC loss, 2) whether the BMC changes were different in groups without or with a bar connecting the implants and 3) whether the presence of mandibular osteoporosis affects the loss of bone height around the implants. The material consisted of 22 long-term edentulous healthy persons, 18 women and 4 men from 54 to 78 years of age with 1 Astra Tech Dental Implant in both canine regions, connected by a bar in half of the patients. BMC measurements were performed in vivo by dual-photon scanner at baseline, just after attachment insertion, at 2-year and 5-year visits. Mandibular osteoporosis was estimated by comparing baseline BMC values with normal mandibular BMC values for young adults of same gender. Loss of bone height around implants was measured on periodically identical intraoral radiographs. The fixed parts of the implant-system were stable during the trial in all patients. 1) the increased function after this treatment seems to cause a load-related bone formation which minimizes the physiologic age-related mandibular BMC loss, 2) this effect seems to be independent of attachment system and 3) mandibular osteoporosis prior to implant treatment may be a risk factor for bone loss around implants. However, this treatment can be recommended also in osteoporotic persons.

Quantitative assessment of bone mineral content in dental radiography —Methodology and clinical usefulness

Various techniques have been developed for measuring bone mineral content in medical examination and treatment these days1–6). In the dento-maxilo-facial region, mandibular bone mineral content has been investigated in connection with bone diminuation in the mandible with aging, postmenopausal osteoporosis and renal osteodystrophy7–9). However, because it is difficult to adapt these techniques to the jaw bone, periapical radiograms were used for measurement of bone mineral content on the jaw bone. Although aluminum (Al) or copper (Cu) steps can be radiographed on the film simultaneously and the density of the images were converted to Al or Cu-equivalent values for the quantitative densitometric measurment by optical density scanning, it was too time-consuming and was not practical in the clinical setting. Thus, we have developed a system to constitute aluminum equivalent images by using a TV system and computer processing10,11). The purpose of this study was to present the method of aluminum equivalent imaging and to discuss its clinical application.

Steroid-induced mandibular bone loss in relation to marginal periodontal changes.

Long-term high-dose glucocorticosteroid treatment may be suspected as causing profound marginal periodontal bone loss due to the immunosuppressive/antiinflammatory effects and due to the osteoporotic side-effects. This study comprised an analysis of the loss of the mandibular and forearm bone mineral content (BMC), measured in vivo by dual-photon scanner, in relation to the concomitant changes of the periodontal indices (visible plaque, gingival bleeding, loss of attachment) in 17 acute nephrotic dentate patients undergoing intensive steroid treatment for 12 months. The measurements were performed at start of treatment, when all patients were considered healthy as regards the skeleton, and at the 6-month and 12-month follow-up. The mean BMC loss at the standard sites of the mandible and the forearm bones was 5.6%/year at both sites. No significant changes could be demonstrated in the periodontal indices (P greater than 0.10), and no relation was found between the mandibular BMC loss and the periodontal condition (R = 0.06, P greater than 0.10). In conclusion, profound marginal periodontal bone loss does not seem to be a prominent side-effect of long-term glucocorticosteroid treatment, although the degree of induced osteopenia in the mandible corresponds to that in other cortical bones of the skeleton.

The mandibular bone mineral content in relation to vestibulolingual sulcoplasty. A 2-year follow-up

The bone mineral content (BMC) in mandibles can now be measured in vivo with high precision by a specially constructed dual-photon scanner. This study analyzed, over a 2-year period, the BMC loss of endentulous mandibles in a group of young and older women after vestibulolingual sulcoplasty with free skin grafts, and its relationship to the initial mandibular BMC and the age-related mandibular BMC loss. BMC in the denture-wearing site and the standard site of the mandible was measured by this method. A significant negative relationship was found between the initial BMC values in the standard site and the BMC loss (in percent) in the denture-wearing site in both age groups, and a significant positive relationship between the BMC loss (in percent) in the two sites of the mandible in the elder group. The rate of residual ridge reduction may be predicted from the initial mandibular BMC value and seems to be dependent on the age-related mandibular BMC loss.

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.

Bone mineral content by photon absorptiometry of the mandible compared with that of the forearm and the lumbar spine.

A new method for measuring the bone mineral content (BMC) of the mandible by dual-photon absorptiometry (DPA) has recently been introduced. The purpose of the present investigation therefore was to examine the long-term precision for 32 months in vitro and in vivo for assessment of BMC in the mandible and to examine the relationship in vivo among BMC of the mandible, the forearms, and the lumbar spine as measured by DPA and/or single-photon absorptiometry (SPA). For comparison, the relationship between forearm BMC as measured by DPA and SPA was studied. The long-term precision of the mandibular BMC was 0.8% in vitro, independent of age and change of radioactive source, and 2.1% by assessment in vivo. A significant relationship (P less than 0.01) was found between BMC of the lumbar spine and the forearms and between the two sets of forearm BMC measured by DPA and SPA. Thus, relative BMC changes of the forearms can be compared without respect to type of forearm bone scanner used. The BMC changes of the mandible can only be evaluated by scanning of the mandible itself. The present DPA bone scanner is suitable for follow-up analyses of the BMC changes of the mandible and the forearms.