Bone remodeling

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Disrupted bone remodeling leads to cochlear overgrowth and hearing loss in a mouse model of fibrous dysplasia.

Disrupted bone remodeling leads to cochlear overgrowth and hearing loss in a mouse model of fibrous dysplasia.

Normal hearing requires exquisite cooperation between bony and sensorineural structures within the cochlea. For example, the inner ear secretes proteins such as osteoprotegrin (OPG) that can prevent cochlear bone remodeling. Accordingly, diseases that affect bone regulation can also result in hearing loss. Patients with fibrous dysplasia develop trabecular bone overgrowth resulting in hearing loss if the lesions affect the temporal bones. Unfortunately, the mechanisms responsible for this hearing loss, which could be sensorineural and/or conductive, remain unclear. In this study, we used a unique transgenic mouse model of increased G s G-protein coupled receptor (GPCR) signaling induced by expression of an
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Potencial of different hydroxyapatites as biomaterials in the bone remodeling

Potencial of different hydroxyapatites as biomaterials in the bone remodeling

Th e histological analysis revealed that in the control group there was presence of primary bone with thickness that varied from thin to thick, presenting bone trabeculae with rows of pavement osteoblasts and no osteoclasts were observed, which shows that this tissue was not under bone remodeling. No foreign body giant cells were observed, which is consistent, since no biomaterial graft was used. The connective tissue associated with the bone tissue (outside the edges of the lesion area) was less cellular, indicating a lower degree of tissue remodeling. In the central region of the medullary canal, small areas of primary bone tissue (trabecular bone) mixed with the bone marrow can be observed in some samples of the same group, whereas in other samples only red bone marrow was observed inside the spinal canal.
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Life-history traits of the Miocene Hipparion concudense (Spain) inferred from bone histological structure.

Life-history traits of the Miocene Hipparion concudense (Spain) inferred from bone histological structure.

In order to gain knowledge on the life history, physiology, and growth patterns of equids during their evolutionary history, we analyzed the histology of the Neogene equid Hipparion. The genus Hipparion characterizes the Upper Miocene and Pliocene faunas of Eurasia. It represents an intermediate stage of horse evolution characterized by: i) a medium albeit highly variable body size; ii) a moderate-to-high degree of hypsodonty; and iii) a partial reduction of the autopodium to a major central toe and two reduced lateral ones (e.g [14]). In the present paper, we first describe and compare the histology (microstructure, vascular pattern, extent and distribution of bone remodeling, and number and distribution of growth marks) of a large sample of limb bones of Hipparion concudense from the upper Miocene site of Los Valles de Fuentiduen˜a (Segovia province, Spain). These compar- isons enabled us to establish the reliability of metapodials for skeletochronology. Based upon this assumption and on the abundance of third metapodials in fossil assemblages, we analyzed two Spanish Miocene populations of Hipparion concudense from different ages and environments [15–19], inferring the life history traits of this species and assessing the influence of different environments on its development. The histological data obtained allowed us to: i) identify different ontogenetic stages; ii) establish the growth pattern and the age of skeletal maturity of Hipparion concudense; and iii) propose tentative estimations of the individ- uals’ age at death and the population structure for both H. concudense samples.
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Buccal bone loss after immediate implantation can be reduced by the flapless approach

Buccal bone loss after immediate implantation can be reduced by the flapless approach

indicat ions of bone t o implant cont act and t he result s were remarkably similar bet ween t he groups. The buccal BIC in bot h groups is numerically higher when compared t o t he lingual BIC result s, and st at ist ically signif icant in t he f lap group (t able 1). The analysis under f luorescent microscopy showed bone remodeling in t he groups evaluat ed. The old bone always appeared darker and wit hout labeling. Calcein green appeared in very well delineat ed green bands (f ig. 5, 6A) as did in red t he alizarin red marker, which in some specimens also showed a smeared dif f use pat t ern (f ig. 5, 6B); oxyt et racyclin showed t hin yellow- green lines (f ig. 5, 6C) and f inally calcein blue was charact erized by a sof t blue color in a very dif f use pat t ern (f ig. 5 and 6D). In many specimens t he secondary ost eons were demonst rat ed by t he deposit ion of t he labels in a concent ric arrangement . The bone marker quant if icat ions sequent ially represent ed t he healing pat t ern of each dif f erent group. The percent ages of newly f ormed bone in t he dif f erent part s are described in t ables 2, 3 and 4. Table 2 represent s t he analysis bet ween t he f lap and
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Biology of bone tissue: structure, function, and factors that influence bone cells

Biology of bone tissue: structure, function, and factors that influence bone cells

Bone tissue is continuously remodeled through the concerted actions of bone cells, which include bone resorption by osteoclasts and bone formation by osteoblasts, whereas osteocytes act as mechanosensors and orchestrators of the bone remodeling process. his process is under the control of local (e.g., growth factors and cytokines) and systemic (e.g., calcitonin and estrogens) factors that all together contribute for bone homeostasis. An imbalance between bone resorption and formation can result in bone diseases including osteoporosis. Recently, it has been recognized that, during bone remodeling, there are an intricate communication among bone cells. For instance, the coupling from bone resorption to bone formation is achieved by interaction between osteoclasts and osteoblasts. Moreover, osteocytes produce factors that inluence osteoblast and osteoclast activities, whereas osteocyte apoptosis is followed by osteoclastic bone resorption. he increasing knowledge about the structure and functions of bone cells contributed to a better understanding of bone biology. It has been suggested that there is a complex communication between bone cells and other organs, indicating the dynamic nature of bone tissue. In this review, we discuss the current data about the structure and functions of bone cells and the factors that inluence bone remodeling.
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Impact of marked weight loss induced by bariatric surgery on bone mineral density and remodeling

Impact of marked weight loss induced by bariatric surgery on bone mineral density and remodeling

Data about the impact of bariatric surgery (BS) and subsequent weight loss on bone are limited. The objective of the present study was to determine bone mineral density (BMD), bone remodeling metabolites and hormones that influence bone trophism in premenopausal women submitted to BS 9.8 months, on average, before the study (OGg, N = 16). The data were compared to those obtained for women of normal weight (CG, N = 11) and for obese women (OG, N = 12). Eight patients in each group were monitored for one year, with the determi- nation of BMD, of serum calcium, phosphorus, magnesium, parathy- roid hormone, 25-hydroxyvitamin D, insulin-like growth factor-I (IGF-I) and osteocalcin, and of urinary calcium and deoxypyridino- line. The biochemical determinations were repeated every three months in the longitudinal study and BMD was measured at the end of the study. Parathyroid hormone levels were similar in the three groups. IGF-I levels (CG = 332 ± 62 vs OG = 230 ± 37 vs OGg = 128 ± 19 ng/ mL) were significantly lower in the operated patients compared to the non-operated obese women. Only OGg patients presented a signifi- cant fall in BMD of 6.2% at L1-L4, of 10.2% in the femoral neck, and of 5.1% in the forearm. These results suggest that the weight loss induced by BS is associated with a significant loss of bone mass even at sites that are not influenced by weight overload, with hormonal factors such as IGF-I being associated with this process.
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Dental Press J. Orthod.  vol.19 número6

Dental Press J. Orthod. vol.19 número6

The effects of ethanol on bone remodeling re- main controversial, but the common hypothesis is that ethanol affects bone metabolism. Differences in variables such as age and time of ethanol con- sumption could explain discrepant results. In addi- tion, no consensus has yet been reached on which factor, whether increased resorption or decreased neoformation, acts as the major mediator induc- ing bone loss as a result of ethanol consumption. 12

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Nutritional aspects of the prevention and treatment of osteoporosis

Nutritional aspects of the prevention and treatment of osteoporosis

Osteoporosis is a global health problem characterized by low bone mass and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture. Nutrition plays a critical role in reducing the risk of osteoporosis through its effect on all of these fragility factors, especially on the development and maintenance of bone mass. An adequate calcium, vitamin D and protein intake resulted in reduced bone remodeling, better calcium retention, reduced age-related bone loss, and reduced fracture risk. Recent evidence indicates that a healthy dietary pattern including dairy products (mainly fat free), fruit and ve- getables and adequate amounts of meat, ish and poultry is positively related to bone health. Furthermore, mineral and vitamin supplementation should be closely monitored by health pro- fessionals since it could have adverse effects and be insuficient to ensure optimal protection of bone health. Arq Bras Endocrinol Metab. 2010;54(2):179-85
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Dental Press J. Orthod.  vol.19 número2

Dental Press J. Orthod. vol.19 número2

The early phase of orthodontic tooth movement always involves an acute inflammatory response, char- acterized by periodontal vasodilatation and migration of leucocytes out of the capillaries. These migratory cells produce various cytokines, the local biome- chanical signal molecules that interact with the entire population of native paradental cells. Cytokines evoke the synthesis and secretion of numerous mediators by target cells, including growth factors, prostaglandins and other cytokines. Subsequent biological events oc- cur and result in bone remodeling to accommodate movement of the tooth. 10,11
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A new bone tissue remodeling algorithm combining mechanical stimuli with cellular dynamics

A new bone tissue remodeling algorithm combining mechanical stimuli with cellular dynamics

In the first series of tests, the bone remodeling algorithm was applied to 2D bone micro- patches. The examples ran in FEMAS used the unit square 2D patch present in Figure 5.5a. To validate the bone trabecular remodeling algorithm, it was applied a compressive stress decreasing linearly from the top. The node displacement was constrained in the x direction along the line x = 0 and on the axis’ origin in both x and y directions. These natural and essential boundary conditions, as well as the the benchmark model [91] used to compare the results, are present in Figure 5.5b and Figure 5.5 c. This benchmark example presents a very specific trabecular morphology existent in long bones. Thus, trabecular bone is typically located at the proximal ends of these types of bones, having an arrangement relatively regular that reflects the direction of the principal mechanical stresses to which this kind of bone is being subjected.
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Use of the plasma CTX for assessing the bone activity of the mandible among osteopenic and osteoporotic patients

Use of the plasma CTX for assessing the bone activity of the mandible among osteopenic and osteoporotic patients

Abstract: The aim of this study was to determine whether the plasma CTX bone remodeling marker is useful for indicating the bone meta- bolic activity level of the mandible. Thirty-six patients were selected; all were postmenopausal and aged 50 years or over. In accordance with the WHO criteria for osteoporosis, a control group was set up (n = 10) in which the T-score was greater than –1 and a diseased group with T- score less than –1. Using MDP- 99m Tc samples, the radioisotope uptake in

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Braz. Dent. J.  vol.27 número4

Braz. Dent. J. vol.27 número4

In an endeavor to elucidate the relationship between the genetic factor and peri-implantitis, genotypes and allele frequencies in specific regions in BMP4, FGF3, FGF10 and FGFR1 genes were evaluated using the data from the International HapMap Project (20). The results of the single marker showed that BMP4 rs2761884 (G>T) and FGF3 rs4631909 (C>T) substitutions were associated with absence of peri-implantitis and there seems to be no major influence of the other gene encoding mediator in bone remodeling. However, when different regions in the same gene were analyzed together, in an endeavor to understand the effect of the different regions responsible for the expression of the gene, an association among GGGA and GAAA BMP4, TGCG FGF3 and CCTG FGF10 haplotypes with pathologic peri-implant bone loss was clearly observed.
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Dental Press J. Orthod.  vol.22 número1

Dental Press J. Orthod. vol.22 número1

It is possible to airm that the conventional orth- odontic movement with brackets and wires limits the dislocation to the individuality of each tooth. In con- ventional orthodontics, we have a tooth-by-tooth movement. When orthodontics is applied considering that bones are in constant remodeling process, the set of well-anchored teeth and roots will be moved and replaced together with the bone, as a whole. Dental movements do not occur only at the alveolus level. Bone remodeling also happens in the maxilla and mandible bones, or in a speciic maxillary region to be eventually redesigned in a morphological way.
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Hormones and bone

Hormones and bone

5. Bilezikian JP, Matsumoto T, Bellido T, Khosla S, Martin J, Recker R, et al. Targeting bone remodeling for the treatment of osteo- porosis: summary of the proceedings of an ASBMR workshop. J Bone Miner Res. 2009;24(3):373-85.

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Arq Bras Endocrinol Metab  vol.50 número4

Arq Bras Endocrinol Metab vol.50 número4

Paget’s disease of bone is usually asympto- matic. In most cases it is detected accidentally through radiological findings or by the serum increase in alkaline phosphatase while other clinical conditions are being investigated (23). Pain and deformity are the most common presentations. The pain arises from the pagetic lesion itself or, more frequently, from indirect complications such as degenerative arthritis, nervous compression or osteosarcoma. Other major causes of pain are increased vascularization, distor- tions of the periosteum resulting from the disorgani- zation of bone remodeling and focal mechanical trau- mas (24). Hypertrophy of bone in the subchondral region may damage the cartilage, leading to osteoarthritis. Distinguishing pain of pagetic origin from that resulting from osteoarthritis is difficult. A response to the specific treatment for PDB may clari- fy this question.
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Effects of low-intensity pulsed ultrasound on new trabecular bone during bone-tendon junction healing in a rabbit model: a synchrotron radiation micro-CT study.

Effects of low-intensity pulsed ultrasound on new trabecular bone during bone-tendon junction healing in a rabbit model: a synchrotron radiation micro-CT study.

Bone healing is usually composed of four distinct but overlapping stages: 1) the early inflam- matory response; 2) soft callus formation; 3) hard callus formation and 4) late bone remodeling [37]. The remodeling process of new bone is crucial to restore the function of the damaged structure [38], and it is accomplished during the remodeling stage in which the irregular and disorderly woven bone callus converts into lamellar bone with orderly bone resorption, eventu- ally restoring the original trabecular bone configuration, structure and mechanical properties [37, 39, 40]. In the present study, quantitative analysis of the morphological parameters showed that the osteogenic effect was more active in week 8 during the healing process, and the remod- eling of new trabecular bone after week 8 was more advanced in the LIPUS group. Although the amount of new bone was augmented with healing time, the bone volume fraction of the new trabecular bone decreased with greater internal microarchitecture variation. For example, the new trabecular bone was thicker with regular arrangement, and the separation was enlarged with marrow cavity formation. These results suggested that LIPUS was also able to accelerate bone remodeling, which occurred more slowly in the control group.
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Hormônio do crescimento no processo de osseointegração de implantes de titânio: estudo experimental e revisão de literatura

Hormônio do crescimento no processo de osseointegração de implantes de titânio: estudo experimental e revisão de literatura

The purpose of this study was to determine whether recombinant human growth hormone (rhGH) would induce the osseointegration. Fourteen adult male rabbits received two nanotextured titanium implants in the tibia. In the rhGH- treated group a layer of 1 IU of rhGH was applied to each osteotomy. None was applied at the control animals. Animals were sacrificed at 14 and 42 days. In the histological and light microscopic evaluation at 14 days was observed in rhGH- treated group acceleration in bone repair and presence of a lamellar bone in periimplant area. At 42 days theres no difference in the new bone formation between the groups, but the rhGH-treated group had was at an advanced stage of bone remodeling. On SEM analysis at 14 days the rhGH-treated group showed a uniform and abundant bone tissue coating attached to the implants, and at 42 days, there were no differences between groups. The biomechanical testing had stress values: 59.26 N/cm 2 for the rhGH-treated group and 33.88
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Estudo histológico dos enxertos ósseos homólogos humanos.

Estudo histológico dos enxertos ósseos homólogos humanos.

Considering that the death of a tissue is not determined wi- thin a static event (biological death of the individual), being ra- ther a sequence of events at cell level, the study has also evalu- ated in the anatomical specimens a series of characteristics re- lated to living tissues, such as vascularization, bone-matrix pre- servation, presence of inflammatory process, fibrosis, and bone remodeling.

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Bone regeneration in mandible defect with autograft bone and cell suspension from bone marrow in rabbits

Bone regeneration in mandible defect with autograft bone and cell suspension from bone marrow in rabbits

On the other hand, the two BMG rabbits that did not present increased radio-opacity on the 14 th day showed bone bridge formation in the last assessment, showing that the early or late increase in bone density did not correspond to a better reconstruction. It is difficult to explain the reason for these results, as little is known about how the stem cells act on bone reconstruction and when they play a primary or secondary role. They might provide not only bone progenitor cells, but also growth factors that that can modulate osteoinducing action (Rizzo et al., 2005). Or even the process of reabsorption or replacement with bone tissue, when established, might have occurred with a higher number of cells.
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Int. Arch. .  vol.19 número2

Int. Arch. . vol.19 número2

The 3 patients with sphenochoanal polyp presented symp- toms of unilateral nasal obstruction, and 2 suffered from frontal or retro-orbital headache. Video endoscopy was diag- nostic in all 3 cases, revealing polypoid tumor in sphenoeth- moidal recess. CT showed an expansive homogeneous image with evidently precise limits in the nasal cavity, with no evidence of bone erosion (►Fig. 6). Patients who underwent endoscopic transethmoidal sphenoidal sinusectomy showed no signs of recurrence for at least 1 year postoperatively.

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