Human mandibular trabecular bone density correlation with mechanical strength: implications for implant dentistry.

PURPOSE: The prognosis of a dental implant depends on the mechanical properties of the bone. The preoperative diagnosis of bone quality has become more important, because the immediate loading procedure is now widely used, and a firm initial stability is required. Quantitative computed tomography (QCT) is an effective method of determining selectively the bone mineral density (BMD) of the trabecular bone mostly responsible for the survival of the implant. In this project, we investigated the relationship between the BMD measured by QCT and the mechanical strength of the mandible. MATERIALS AND METHODS: The BMD (mg/mL) of 58 trabecular bone specimens from 6 embalmed human cadaver mandibles were obtained using QCT. The compressive strength to break point was performed with a mechanical device. Each specimen was washed and weighed. RESULTS: The mean values of BMD for the anterior, premolar, and molar region were 633.3, 571.0, and 518.3 mg/mL, respectively. The mean values of compressive strength were 0.237, 0.216, and 0.196 kN, and the ash weights were 0.047, 0.044, and 0.039 g, respectively. There was a positive correlation between the BMD and the mechanical strength (R = 0.77) and between the ash weight and the mechanical strength (R = 0.84). CONCLUSION: There was strong correlation of bone strength, bone mineral, and bone density by QCT. QCT is an excellent preoperative diagnostic tool to select the most mechanically appropriate implant for initial stability and improve the survival prognosis.

En Balance participants decrease dietary fat and cholesterol intake as part of a culturally sensitive Hispanic diabetes education program.

PURPOSE: The purpose of this study was to assess dietary intake habits of Mexican American Hispanic adults participating in the En Balance diabetes education program. METHODS: En Balance is a 3-month culturally sensitive diabetes education intervention for Spanish-speaking Hispanics. Of the 46 participants enrolled, 39 mainly Mexican American Hispanic adults with type 2 diabetes completed the En Balance program. Participants lived in the Riverside and San Bernardino counties of California, and all participants completed the program by June 2008. Dietary intake was assessed at baseline and at 3 months using the validated Southwest Food Frequency Questionnaire. RESULTS: Clinically important decreases in glycemic control and serum lipid levels were observed at the end of the 3-month program. The baseline diet was characterized by a high intake of energy (2478 ± 1140 kcal), total fat (87 ± 44 g/day), saturated fat (28 ± 15 g/day), dietary cholesterol (338 ± 217 mg/day), and sodium (4236 ± 2055 mg/day). At 3 months, the En Balance group mean intake of dietary fat (P = .045) and dietary cholesterol (P = .033) decreased significantly. Low dietary intakes of docosahexaenoic acid, eicosapentaenoic acid, and vitamin E were also observed in these adults with type 2 diabetes. CONCLUSIONS: The En Balance program improved glycemic control and lipid profiles in a group of Hispanic diabetic participants. En Balance also promoted decreases in dietary fat and dietary cholesterol intake.

Bone density assessments of dental implant sites: 2. Quantitative cone-beam computerized tomography.

PURPOSE: Bone density was evaluated in designated implant sites using a novel volumetric computerized tomographic device. Those measurements were then compared with traditional quantitative computerized axial tomography and subjective bone density evaluation. MATERIALS AND METHODS: Sixty-three potential sites for implant placement in jaws from 9 human cadavers were used. Indicator rods 2 mm in diameter were placed in all sites. Radiographic images representing 1-mm buccolingual slices immediately mesial and distal to the rods were selected. Bone density in Hounsfield units was assessed using quantitative cone-beam computerized tomography (QCBCT) and quantitative computerized tomography (QCT) in a standardized implant area superimposed on the images. Bone density was also subjectively evaluated by 2 independent examiners using the Lekholm and Zarb classification. RESULTS: The QCBCT bone density values were generally found to be higher than the corresponding QCT measurements. The correlations between the QCT and QCBCT values, however, were very high in spite of this systematic difference between the 2 methods. The Lekholm and Zarb ratings for the 2 examiners showed correlation coefficients ranging between 0.46 and 0.60 for the relationships with the QCBCT values. For each of the scores used for the subjective classification, however, a wide range of corresponding QCBCT values was observed. DISCUSSION: High dosage has been the major impediment to the utilization of CT in implant dentistry. The development of a reliable volumetric CT alternative with reduced radiation should provide an effective method for the assessment of both bone quantity and bone density. CONCLUSIONS: Access to objective radiographic bone density values should constitute a valuable supplement to subjective bone density evaluations prior to implant placement. QCBCT could be considered an alternative diagnostic tool for preoperative bone density evaluation, especially since the reported radiation dose is minimal.

Aortic calcification and the risk of osteoporosis and fractures.

We investigated the relation between computed tomography measures of aortic calcification and values for bone density and the number of fragility fractures in 2348 healthy, postmenopausal women. To determine whether increases in vascular calcification and bone loss progress in parallel, baseline values were compared with measurements obtained 9 months to 8 yr later in a subgroup of 228 women. Of the 2348 subjects studied, 70% had osteoporosis, 30% had at least one vertebral fracture, and 9% had at least one hip fracture. Aortic calcifications were inversely related to bone density and directly related to fractures. After adjusting for age and potential confounders, measures for aortic calcification predicted 26.1% of the variance in bone density (P < 0.001). Compared with women without calcification, the odds ratios for vertebral and hip fractures in those with calcification were estimated to be 4.8 (95% confidence interval, 3.6-6.5) and 2.9 (95% confidence interval, 1.8-4.8), respectively. The subgroup analysis of 228 women longitudinally studied showed that the percentage of yearly increase in aortic calcification accounted for 47% of the variance in the percentage rate of bone loss (P < 0.001). Moreover, a strong graded association was observed between the progression of vascular calcification and bone loss for each quartile. Women in the highest quartile for gains in aortic calcification had four times greater yearly bone loss (5.3 vs.1.3% yearly; P < 0.001) than women of similar age in the lowest quartile. Smaller, but highly significant differences were also found between all other quartiles. We conclude that aortic calcifications are a strong predictor for low bone density and fragility fractures.

Bone density assessments of dental implant sites: 1. Quantitative computed tomography.

PURPOSE: This study was designed to evaluate variations of bone density in designated implant sites using quantitative computed tomography (QCT) and to compare the QCT measurements to subjective evaluation of bone density. MATERIALS AND METHOD: Sixty-two designated implant sites in jaws of 9 human cadavers were used. Indicator rods, 2 mm in diameter, were placed in all sites. CT images representing 1-mm buccolingual slices immediately mesial and distal to the rods were selected. Bone density (in Hounsfield units) was assessed in a standardized implant area superimposed on the images and was also subjectively evaluated by 2 independent examiners using the Lekholm and Zarb classification. RESULTS: QCT results demonstrated that bone densities may vary markedly when different areas of a designated implant site are compared. The Lekholm and Zarb ratings for the 2 examiners showed coefficients of correlation ranging between 0.5 to 0.7 for the relationships with the QCT values. Within each of the scores used for the subjective classification, however, a wide range of QCT values was observed. DISCUSSION: The results emphasize the importance of the use of radiographic methods prior to implant placement that allow topographically precise assessments of bone density in the region of interest. CONCLUSION: Access to QCT values should constitute a valuable supplement to subjective bone density evaluations prior to implant placement.