Abstract: Glucocorticoid-induced osteoporosis (GIO) is the most common form of secondary osteoporosis. Fractures, which are often asymptomatic, may occur in as many as 30-50% of patients receiving chronic glucocorticoid therapy. Vertebral fractures occur early after exposure to glucocorticoids, at a time when bone mineral density (BMD) declines rapidly. Fractures tend to occur at higher BMD levels than in women with postmenopausal osteoporosis. In human subjects, the early rapid decline in BMD is followed by a slower progressive decline in BMD. Glucocorticoids have direct and indirect effects on the skeleton. The primary effects are on osteoblasts and osteocytes. Glucocorticoids impair the replication, differentiation and function of osteoblasts and induce the apoptosis of mature osteoblasts and osteocytes. These effects lead to a suppression of bone formation, a central feature in the pathogenesis of GIO. Glucocorticoids also favor osteoclastogenesis and as a consequence increase bone resorption. Bisphosphonates are effective in the prevention and treatment of GIO. Anabolic therapeutic strategies are under investigation.

Abstract: We used μCT and histomorphometry to assess age-related changes in bone architecture in male and female C57BL/6J mice. Deterioration in vertebral and femoral trabecular microarchitecture begins early, continues throughout life, is more pronounced at the femoral metaphysis than in the vertebrae, and is greater in females than males. Introduction: Despite widespread use of mice in the study of musculoskeletal disease, the age-related changes in murine bone structure and the relationship to whole body BMD changes are not well characterized. Thus, we assessed age-related changes in body composition, whole body BMD, and trabecular and cortical microarchitecture at axial and appendicular sites in mice. Materials and Methods: Peripheral DXA was used to assess body composition and whole body BMD in vivo, and μCT and histomorphometry were used to measure trabecular and cortical architecture in excised femora, tibia, and vertebrae in male and female C57BL/6J mice at eight time-points between 1 and 20 mo of age (n = 6–9/group). Results: Body weight and total body BMD increased with age in male and female, with a marked increase in body fat between 6 and 12 mo of age. In contrast, trabecular bone volume (BV/TV) was greatest at 6–8 wk of age and declined steadily thereafter, particularly in the metaphyseal region of long bones. Age-related declines in BV/TV were greater in female than male. Trabecular bone loss was characterized by a rapid decrease in trabecular number between 2 and 6 mo of age, and a more gradual decline thereafter, whereas trabecular thickness increased slowly over life. Cortical thickness increased markedly from 1 to 3 mo of age and was maintained or slightly decreased thereafter. Conclusions: In C57BL/6J mice, despite increasing body weight and total body BMD, age-related declines in vertebral and distal femoral trabecular bone volume occur early and continue throughout life and are more pronounced in females than males. Awareness of these age-related changed in bone morphology are critical for interpreting the skeletal response to pharmacologic interventions or genetic manipulation in mice.

Abstract: Using QCT, we made a longitudinal, population-based assessment of rates of bone loss over life at the distal radius, distal tibia, and lumbar spine. Cortical bone loss began in perimenopause in women and later in life in men. In contrast, trabecular bone loss began in young adulthood in both sexes. Introduction Although conventional wisdom holds that bone loss begins at menopause in women and later in life in men, this has not been examined longitudinally in population-based studies using precise technology capable of distinguishing cortical and trabecular bone.

Abstract: It was previously believed that obesity and osteoporosis were two unrelated diseases, but recent studies have shown that both diseases share several common genetic and environmental factors. Body fat mass, a component of body weight, is one of the most important indices of obesity, and a substantial body of evidence indicates that fat mass may have beneficial effects on bone. Contrasting studies, however, suggest that excessive fat mass may not protect against osteoporosis or osteoporotic fracture. Differences in experimental design, sample structure, and even the selection of covariates may account for some of these inconsistent or contradictory results. Despite the lack of a clear consensus regarding the impact of effects of fat on bone, a number of mechanistic explanations have been proposed to support the observed epidemiologic and physiologic associations between fat and bone. The common precursor stem cell that leads to the differentiation of both adipocytes and osteoblasts, as well the secretion of adipocyte-derived hormones that affect bone development, may partially explain these associations. Based on our current state of knowledge, it is unclear whether fat has beneficial effects on bone. We anticipate that this will be an active and fruitful focus of research in the coming years.

Abstract: Low bone mass (osteoporosis) is a silent epidemic of the 21st century, which presently in the UK results in over 200,000 fractures annually at a cost of over one billion pounds. Figures are set to increase worldwide. Understanding the factors which affect bone metabolism is thus of primary importance in order to establish preventative measures or treatments for this condition. Nutrition is an important determinant of bone health, but the effects of the individual nutrients and minerals, other than calcium, is little understood. Accumulating evidence over the last 30 years strongly suggest that dietary silicon is beneficial to bone and connective tissue health and we recently reported strong positive associations between dietary Si intake and bone mineral density in US and UK cohorts. The exact biological role(s) of silicon in bone health is still not clear, although a number of possible mechanisms have been suggested, including the synthesis of collagen and/or its stabilization, and matrix mineralization. This review gives an overview of this naturally occurring dietary element, its metabolism and the evidence of its potential role in bone health.

Abstract: Dual energy x ray absorptiometry (DXA) scans to measure bone mineral density (BMD) at the spine and hip have an important role in the evaluation of individuals at risk of osteoporosis, and in helping clinicians advise patients about the appropriate use of antifracture treatment. Compared with alternative bone densitometry techniques, hip and spine DXA examinations have a number of advantages that include a consensus that BMD results can be interpreted using the World Health Organization T-score definition of osteoporosis, a proven ability to predict fracture risk, proven effectiveness at targeting antifracture therapies, and the ability to monitor response to treatment. This review discusses the evidence for these and other clinical aspects of DXA scanning, including its role in the new WHO algorithm for treating patients on the basis of their individual fracture risk.

Abstract: BMD, bone microarchitecture, and bone mechanical properties assessed in vivo by finite element analysis were associated with wrist fracture in postmenopausal women. Introduction: Many fractures occur in individuals with normal BMD. Assessment of bone mechanical properties by finite element analysis (FEA) may improve identification of those at high risk for fracture. Materials and Methods: We used HR-pQCT to assess volumetric bone density, microarchitecture, and μFE-derived bone mechanical properties at the radius in 33 postmenopausal women with a prior history of fragility wrist fracture and 33 age-matched controls from the OFELY cohort. Radius areal BMD (aBMD) was also measured by DXA. Associations between density, microarchitecture, mechanical parameters and fracture status were evaluated by univariate logistic regression analysis and expressed as ORs (with 95% CIs) per SD change. We also conducted a principal components (PCs) analysis (PCA) to reduce the number of parameters and study their association (OR) with wrist fracture. Results: Areal and volumetric densities, cortical thickness, trabecular number, and mechanical parameters such as estimated failure load, stiffness, and the proportion of load carried by the trabecular bone at the distal and proximal sites were associated with wrist fracture (p < 0.05). The PCA revealed five independent components that jointly explained 86.2% of the total variability of bone characteristics. The first PC included FE-estimated failure load, areal and volumetric BMD, and cortical thickness, explaining 51% of the variance with an OR for wrist fracture = 2.49 (95% CI, 1.32–4.72). Remaining PCs did not include any density parameters. The second PC included trabecular architecture, explaining 12% of the variance, with an OR = 1.82 (95% CI, 0.94–3.52). The third PC included the proportion of the load carried by cortical versus trabecular bone, assessed by FEA, explaining 9% of the variance, and had an OR = 1.61 (95% CI, 0.94–2.77). Thus, the proportion of load carried by cortical versus trabecular bone seems to be associated with wrist fracture independently of BMD and microarchitecture (included in the first and second PC, respectively). Conclusions: These results suggest that bone mechanical properties assessed by μFE may provide information about skeletal fragility and fracture risk not assessed by BMD or architecture measurements alone and are therefore likely to enhance the prediction of wrist fracture risk.

Abstract: We assessed the role of low aBMD and impaired architecture—assessed by an HR-pQCT system—in a case-control study of postmenopausal women with fractures. Vertebral and nonvertebral fractures are associated with low volumetric BMD and architectural alterations of trabecular and cortical bone, independent of aBMD assessed by DXA. Introduction: Alterations of bone architecture and low BMD both contribute to skeletal fragility, but the contribution of cortical and trabecular architecture, independently of areal BMD (aBMD), to the risk of fracture in postmenopausal women has not been thoroughly evaluated. We assessed the role of impaired architecture and low BMD in postmenopausal women with fractures. Materials and Methods: A matched case-control study in women from the OFELY cohort was performed after 13 years of follow-up. One hundred one women (mean, 73.7 ± 8 years) who sustained a fragility fracture during the follow-up of the study were age-matched with one control who never had a fracture. Density and architecture at the distal radius and tibia were measured with high-resolution pQCT (HR-pQCT) using an XTreme CT (Scanco Medical AG, Bassersdorf, Switzerland). aBMD at the total hip and ultradistal radius was measured by DXA. Results: There were 80 peripheral fractures in 72 women, 44 vertebral fractures in 34 women, and both types of fractures in 5 women over the 14 years of follow-up. At the distal radius, women with fractures had lower volumetric total (D tot) and trabecular (D trab) BMDs, BV/TV, cortical thickness (Cort Th), trabecular number (TbN), and trabecular thickness (TbTh) and higher trabecular separation (TbSp) and distribution of trabecular separation (TbSpSd) than controls without fractures. In a logistic model, each SD decrease of volumetric total and trabecular densities was associated with a significantly increased risk of fracture at both sites (ORs ranged from 2.00 to 2.47). After adjusting for aBMD measured by DXA at the ultradistal radius, differences between cases and controls remained significant for D trab, and there was a similar trend for TbN, TbSp, and TbSpSd, with adjusted ORs ranging from 1.32 to 1.50. At the distal tibia, before and after adjusting for total hip aBMD, differences between cases and controls remained significant for D tot, D trab, Cort Th, and TbTh, with adjusted ORs ranging from 1.80 to 2.09. Conclusions: In postmenopausal women, vertebral and nonvertebral fractures are associated with low volumetric BMD and architectural alterations of trabecular and cortical bone that can be assessed noninvasively and that are partially independent of aBMD assessed by DXA.

Abstract: Summary Background Tamoxifen preserves bone in postmenopausal women, but non-steroidal aromatase inhibitors accelerate bone loss and increase fracture risk. We aimed to study the effect on bone health in a subgroup of women included in the Intergroup Exemestane Study (IES), a large randomised trial that compared the switch to the steroidal aromatase inhibitor exemestane with continuation of tamoxifen in the adjuvant treatment of postmenopausal breast cancer. Methods Results were analysed from 206 evaluable patients from the IES, in which postmenopausal women with histologically confirmed and completely resected unilateral breast cancer (that was oestrogen-receptor positive or of unknown status), who were disease-free after 2–3 years of treatment with tamoxifen were randomised to continue oral tamoxifen 20 mg/day or switch to oral exemestane 25 mg/day to complete a total of 5 years of adjuvant endocrine therapy. The primary endpoint was change in bone-mineral density (BMD) assessed by dual energy X-ray absorptiometry. Changes in biochemical markers of bone turnover were also analysed in this substudy, and the incidence of fractures in the entire study reported. The IES is registered on the Current Controlled Trials website http://www.controlled-trials.com/ISRCTN11883920. Findings Within 6 months of switching to exemestane, BMD was lowered by 0·051 g/cm 3 (2·7%; 95% CI 2·0–3·4; p 3 (1·4%; 0·8–1·9; p Interpretation These results indicate that the increase in survival shown previously with the IES switch strategy is achieved at the expense of some detriment to skeletal health, so the risk-benefit ratio to women needs to be individually assessed.

Abstract: ContextIt is widely believed that fractures resulting from high trauma are not osteoporotic; however, this assumption has not been studied prospectively.ObjectiveTo examine the association between bone mineral density (BMD) and high-trauma fracture and between high-trauma fracture and subsequent fracture in older women and men.Design, Setting, and ParticipantsTwo prospective US cohort studies in community-dwelling adults 65 years or older from geographically diverse sites. The Study of Osteoporotic Fractures followed up 8022 women for 9.1 years (1988-2006). The Osteoporotic Fractures in Men Study followed up 5995 men for 5.1 years (2000-2007).Main Outcome MeasuresHip and spine BMD were assessed by dual-energy x-ray absorptiometry. Incident nonspine fractures were confirmed by radiographic report. Fractures were classified, without knowledge of BMD, as high trauma (due to motor vehicle crashes and falls from greater than standing height) or as low trauma (due to falls from standing height and less severe trauma).ResultsOverall, 264 women and 94 men sustained an initial high-trauma fracture and 3211 women and 346 men sustained an initial low-trauma fracture. For women, each 1-SD reduction in total hip BMD was similarly associated with an increased risk of high-trauma fracture (multivariate relative hazard [RH], 1.45; 95% confidence interval [CI], 1.23-1.72) and low-trauma fracture (RH, 1.49; 95% CI, 1.42-1.57). Results were consistent in men (high-trauma fracture RH, 1.54; 95% CI, 1.20-1.96; low-trauma fracture RH, 1.69; 95% CI, 1.49-1.91). Risk of subsequent fracture was 34% (95% CI, 7%-67%) greater among women with an initial high-trauma fracture and 31% (95% CI, 20%-43%) greater among women with an initial low-trauma fracture, compared with women having no high- or low-trauma fracture, respectively. Risk of subsequent fracture was not modeled for men.ConclusionsSimilar to low-trauma nonspine fractures, high-trauma nonspine fractures are associated with low BMD and increased risk of subsequent fracture in older adults. High-trauma nonspine fractures should be included as outcomes in osteoporosis trials and observational studies.

Abstract: Context: Patients with elevated PTH and consistently normal serum calcium levels, in whom secondary causes of hyperparathyroidism have been excluded, may represent the earliest presentation of primary hyperparathyroidism (PHPT). Objective: The objective of the study was to characterize patients with normocalcemic PHPT referred to a bone disease unit. Design: This was a longitudinal cohort study. Setting: Ambulatory patients were referred to the metabolic bone disease unit. Patients: The study population included 37 patients [aged 58 yr, range 32–78; 95% female; serum calcium, 9.4 ± 0.1 (sem) mg/dl (2.3 ± 0.02 mmol/liter), reference range, 8.5–10.4 (2.1–2.6 mmol/liter); PTH, 93 ± 5 pg/ml]. Interventions: Interventions included yearly (median 3 yr; range 1–8 yr) physical examination, biochemical indices, and bone mineral density (BMD). Main Outcome Measures: We measured the development of features of PHPT. Results: Evaluation for classical features of PHPT revealed a history of kidney stones in five (14%), ...

Abstract: Background: The study objectives were to determine fracture rates in relation to bone mineral density at various central skeletal sites, using the World Health Organization definition for osteoporosis (T-score –2.5 or less), and to contrast fracture patterns among women 50 to 64 years of age with those among women 65 years of age and older. Methods: Historical cohort study with a mean observation period of 3.2 (standard deviation [SD] 1.5) years. The study group (16 505 women 50 years of age or older) was drawn from the Manitoba Bone Density Program database, which includes all bone mineral density results for Manitoba. Baseline density measurements for the lumbar spine and hip were performed with dual-energy x-ray absorptiometry. Outcomes included the percentage of osteoporotic fractures and the rates of fracture and excess fracture (per 1000 person-years) among postmenopausal women with osteopenia and osteoporosis relative to those with normal bone mineral density (according to the classification of the World Health Organization). Results: The mean age was 65 (SD 9) years, and the mean T-scores for all sites fell within the osteopenic category. There were 765 incident fractures (fracture rate 14.5 [95% confidence interval, CI, 13.5–15.6 [per 1000 person-years). Fracture rates were significantly higher among women 65 years of age or older than among women 50–64 years of age (21.6 [95% CI 19.7–23.4] v. 8.6 [95% CI 7.5–9.7] per 1000 person-years, p Interpretation: In this study, most of the postmenopausal women with osteoporotic fractures had nonosteoporotic bone mineral density values. This finding highlights the importance of considering key clinical risk factors that operate independently of bone mineral density (such as age) when assessing fracture risk.

Abstract: BACKGROUND Androgen deprivation therapy (ADT) in men with prostate cancer is associated with bone loss and fractures. OBJECTIVE To determine whether once-weekly oral bisphosphonate can prevent bone loss and reduce bone turnover in men receiving ADT. DESIGN Randomized, double-blind, placebo-controlled, partial crossover trial. First-year, preplanned analysis of a 2-group, parallel-design phase. SETTING University medical center. PATIENTS 112 men with nonmetastatic prostate cancer receiving ADT. INTERVENTION Alendronate, 70 mg once weekly, or placebo. All patients received calcium and vitamin D supplementation. MEASUREMENTS Bone mineral density of the spine and hip and markers of bone resorption and formation. RESULTS At baseline, 39% of men had osteoporosis and 52% had low bone mass. In men treated with alendronate, bone mineral density increased over 1 year by 3.7% (95% CI, 2.8% to 4.6%; P < 0.001) at the spine and 1.6% (CI, 0.4% to 2.8%; P = 0.008) at the femoral neck. Men in the placebo group had losses of 1.4% (CI, -2.7% to - 0.03%; P = 0.045) at the spine and 0.7% (CI, -1.5% to 0.01%; P = 0.081) at the femoral neck. At 12 months, the difference between the 2 groups was 5.1 percentage points (CI, 3.5 to 6.7 percentage points; P < 0.001) at the spine and was 2.3 percentage points (CI, 1.0 to 3.7 percentage points; P < 0.001) at the femoral neck. Bone turnover statistically significantly decreased with active therapy compared with placebo. The groups did not differ in adverse events. LIMITATIONS The study was short (1 year) and was not powered to detect differences in the frequency of fractures. CONCLUSIONS Bone loss that occurred with ADT was prevented and improved with once-weekly oral alendronate. Because most men have low bone mass or osteoporosis, physicians should assess their patients' bone density and provide preventive and therapeutic measures as appropriate. ClinicalTrials.gov registration number: NCT00048841.

Abstract: Context: Although muscle mass is beneficial to bone, studies on the effect of fat mass on bone have yielded conflicting results. Objective: The aim of this study was to assess the relations between lean and fat mass and bone structure. Design: This study was cross-sectional. Setting: The study was conducted in a general community. Subjects: Subjects included 300 healthy sexually mature adolescents and young adults (150 males and 150 females) between the ages of 13 and 21 yr. Main Outcome Measure: We investigated the relation between dual-energy x-ray absorptiometry (DXA) measures of total body fat and lean mass and bone values obtained with DXA (legs and lumbar spine bone mineral density and bone mineral content) and computed tomography (CT) (cross-sectional and cortical bone areas of the femurs and cross-sectional area and cancellous bone density of the vertebrae). Results: Simple and multiple linear regression analyses showed significant positive relations between DXA lean mass and all CT and DXA measur...

Abstract: Background : the beneficial role of exercise in improving bone mineral density, muscle strength and balance, has been documented predominantly in younger populations. These findings may not apply to elderly populations with limited ability to perform exercises of high intensity. Objective : to examine the effects of Tai Chi (TC) and resistance exercise (RTE) on bone mineral density (BMD), muscle strength, balance and flexibility in community living elderly people. Design : randomised controlled trial, using blocked randomization with stratification by sex. Setting : a community in the New Territories Region of Hong Kong, China. Subjects : one hundred eighty subjects (90 men, 90 women) aged 65-74, were recruited through advertisements in community centres. Methods : subjects were assigned to participate in TC, RTE three times a week, or no intervention (C) for 12 months. Measurements were carried out at baseline, 6 and 12 months. Analyses of covariance (ANCOVA) adjusted for age, and baseline values of variables that were significantly different between groups : i.e. smoking and flexibility for men; quadriceps strength for women. Results : compliance was high (TC 81%, RTE 76%). In women, both TC and RTE groups had less BMD loss at total hip compared with controls. No effect was observed in men. No difference in either balance, flexibility or the number of falls was observed between either intervention or controls after 12 months. Conclusion : the beneficial effects of TC or RTE on musculoskeletal health are modest and may not translate into better clinical outcomes.

Abstract: Studies suggest that isoflavone phytoestrogens, which are found in soy products, reduce bone loss in women, but the evidence is not definitive. Marini and colleagues compared the phytoestrogen geni...

Abstract: Osteoporosis is characterized by low bone mass and compromised bone structure, heritable traits that contribute to fracture risk. There have been no genome-wide association and linkage studies for these traits using high-density genotyping platforms. We used the Affymetrix 100K SNP GeneChip marker set in the Framingham Heart Study (FHS) to examine genetic associations with ten primary quantitative traits: bone mineral density (BMD), calcaneal ultrasound, and geometric indices of the hip. To test associations with multivariable-adjusted residual trait values, we used additive generalized estimating equation (GEE) and family-based association tests (FBAT) models within each sex as well as sexes combined. We evaluated 70,987 autosomal SNPs with genotypic call rates ≥80%, HWE p ≥ 0.001, and MAF ≥10% in up to 1141 phenotyped individuals (495 men and 646 women, mean age 62.5 yrs). Variance component linkage analysis was performed using 11,200 markers. Heritability estimates for all bone phenotypes were 30–66%. LOD scores ≥3.0 were found on chromosomes 15 (1.5 LOD confidence interval: 51,336,679–58,934,236 bp) and 22 (35,890,398–48,603,847 bp) for femoral shaft section modulus. The ten primary phenotypes had 12 associations with 100K SNPs in GEE models at p < 0.000001 and 2 associations in FBAT models at p < 0.000001. The 25 most significant p-values for GEE and FBAT were all less than 3.5 × 10-6 and 2.5 × 10-5, respectively. Of the 40 top SNPs with the greatest numbers of significantly associated BMD traits (including femoral neck, trochanter, and lumbar spine), one half to two-thirds were in or near genes that have not previously been studied for osteoporosis. Notably, pleiotropic associations between BMD and bone geometric traits were uncommon. Evidence for association (FBAT or GEE p < 0.05) was observed for several SNPs in candidate genes for osteoporosis, such as rs1801133 in MTHFR; rs1884052 and rs3778099 in ESR1; rs4988300 in LRP5; rs2189480 in VDR; rs2075555 in COLIA1; rs10519297 and rs2008691 in CYP19, as well as SNPs in PPARG (rs10510418 and rs2938392) and ANKH (rs2454873 and rs379016). All GEE, FBAT and linkage results are provided as an open-access results resource at http://www.ncbi.nlm.nih.gov/projects/gap/cgi-bin/study.cgi?id=phs000007 . The FHS 100K SNP project offers an unbiased genome-wide strategy to identify new candidate loci and to replicate previously suggested candidate genes for osteoporosis.

Abstract: Minimal trauma fractures in bone diseases are the result of bone fragility. Rather than considering bone fragility as being the result of a reduced amount of bone, we recognize that bone fragility is the result of changes in the material and structural properties of bone. A better understanding of the contribution of each component of the material composition and structure and how these interact to maintain whole bone strength is obtained by the study of metabolic bone diseases. Disorders of collagen (osteogenesis imperfecta and Paget's disease of bone), mineral content, composition and distribution (fluorosis and osteomalacia); diseases of high remodeling (postmenopausal osteoporosis, hyperparathyroidism, and hyperthyroidism) and low remodeling (osteopetrosis, pycnodysostosis); and other diseases (idiopathic male osteoporosis, corticosteroid-induced osteoporosis) produce abnormalities in the material composition and structure that lead to bone fragility. Observations in patients and in animal models provide insights on the biomechanical consequences of these illnesses and the nature of the qualities of bone that determine its strength.

Abstract: Osteoporosis is a multifactorial disorder of bone mineral homeostasis affecting the elderly. It is a major public health issue with significant socioeconomic consequences. Recent findings suggest that bone loss-the key manifestation of the disease-is accompanied by architectural deterioration, both affecting the bone's mechanical competence and susceptibility to fracture. This article reviews the potential of quantitative micro MRI (mu-MRI), including a discussion of the technical requirements for image acquisition, processing, and analysis for assessing the architectural implications of osteoporosis and as a means to monitor the response to treatment. With current technology, the resolution achievable in clinically acceptable scan times and necessary signal-to-noise ratio (SNR) is comparable to trabecular thickness. This limited spatial resolution regime demands processing and analysis algorithms designed to operate under such limiting conditions. It is shown that three different classes of structural parameters can be distinguished, characterizing scale, topology, and orientation. There is considerable evidence that osteoporotic bone loss affects all three classes but that topological changes, resulting from conversion of trabecular plates to rods, with the latter's eventual disconnection, are particularly prominent. Clinical applications discussed can be divided into those dealing with assessment of osteoporotic fracture risk as opposed to the study of the effect of disease progression and regression in response to treatment. Current data suggest that noninvasive assessment of cortical and trabecular bone (TB) architecture by mu-MRI may provide new surrogate endpoints to assess the efficacy of intervention in osteoporosis treatment and prevention.

Abstract: Background: Micro-computed tomography (micro-CT) offers significant potential for identifying mineralized structures. However, three-dimensional (3-D) micro-CT of alveolar bone has not been adapted readily for quantification. Moreover, conventional methods are not highly sensitive for analyzing bone loss or bone gain following periodontal disease or reconstructive therapy. The objective of this investigation was to develop a micro-CT methodology for quantifying tooth-supporting alveolar bone in 3-D following experimental preclinical situations of periodontitis or reconstructive therapy.Methods: Experimental in vivo bone loss or regeneration situations were developed to validate the micro-CT imaging techniques. Twenty mature Sprague-Dawley rats were divided into two groups: bone loss (Porphyromonas gingivalis lipopolysaccharide-mediated bone resorption) and regenerative therapy. Micro-CT and software digitized specimens were reconstructed three-dimensionally for linear and volumetric parameter assessment o...

Abstract: Aims: The objective of this study was to determine the relationship between bone density, insertion torque, and implant stability at implant placement Materials and Methods: One-hundred and eight patients were treated with 230 BrÅnemark System implants A computerized tomography (CT) machine was used for pre-operative evaluation of the jaw bone for each patient The maximum insertion torque values were recorded with the OsseoCare equipment Implant stability measurements were performed with the Osstell machine for only 142 implants Results: The mean bone density and insertion torque values were 721 ± 254 Hounsfield unit (HU) and 391 ± 7 N cm for 230 implants, and the correlation was significant (r= 0664, p<0001) The mean bone density, insertion torque, and resonance frequency analysis values were 751 ± 257 HU, 394 ± 7 Nc m, and 705 ± 7 implant stability quotient (ISQ), respectively, for 142 implants Statistically significant correlations were found between bone density and insertion torque values (p<0001); bone density and ISQ values (p<0001); and insertion torque and ISQ values (p<0001) Conclusion: The bone density values from pre-operative CT examination may provide an objective assessment of bone quality, and significant correlations between bone density and implant stability parameters may help clinicians to predict primary stability before implant insertion