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  • 1
    Electronic Resource
    Electronic Resource
    Bacteroides gingivalis activates mouse spleen cells to produce a factor that stimulates resorptive activity of osteoclasts in vitro (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 21 (1986), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Oral microorganisms are generally considered to be responsible for the initiation of inflammatory periodontal disease, but the mechanism by which they cause bone resorption has not yet been established. We report here that the periodontopathic bacterium B. gingivalis activates mouse spleen cells to produce a factor that strongly stimulates osteoclast-mediated mineral resorption. Resorption was measured as the release of 45Ca from prelabeled fetal mouse long bones in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1986.tb01478.x
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  • 2
    Electronic Resource
    Electronic Resource
    Histology of human alveolar bone regeneration with a porous tricalcium phosphate (2001)
    Copenhagen : Munksgaard International Publishers
    Clinical oral implants research 12 (2001), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Porous β-phase tricalcium phosphate particles (pTCP) (Cerasorb®) were used in two patients to restore or augment alveolar bone prior to the placement of dental implants. In one patient, pTCP was used to fill a large alveolar defect in the posterior mandible after the removal of a residual cyst, and in another patient to augment the sinus floor. Biopsies were taken at the time of implant placement, 9.5 and 8 months after grafting, respectively, and processed for hard tissue histology. Goldner-stained histological sections showed considerable replacement of the bone substitute by bone and bone marrow. In the 9.5 months biopsy of the mandible, 34% of the biopsy consisted of mineralised bone tissue and 29% of remaining pTCP, while the biopsy at 8 months after sinus floor augmentation consisted of 20% mineralised bone and 44% remaining pTCP. Bone and osteoid were lying in close contact with the remaining pTCP and were also seen within the micropores of the grafted particles. Tartrate resistant-acid phosphatase (TRAP) multinuclear cells, presumably osteoclasts, were found surrounding, within and in close contact with the pTCP particles, suggesting active resorption of the bone substitute. Remodelling of immature woven bone into mature lamellar bone was also found. No histological signs of inflammation were detected. The limited data presented from these two cases suggest that this graft material, possibly by virtue of its porosity and chemical nature, may be a suitable bone substitute that can biodegrade and be replaced by new mineralising bone tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0501.2001.012004379.x
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  • 3
    Electronic Resource
    Electronic Resource
    Transforming growth factor-β1 incorporated in calcium phosphate cement stimulates osteotransductivity in rat calvarial bone defects (2001)
    Copenhagen : Munksgaard International Publishers
    Clinical oral implants research 12 (2001), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Bone regeneration of the alveolar crest around dental implants is an important factor in the success of implant use. Calcium phosphate cement can be used as a bone substitute and applied clinically as a paste to fill micro- and macroscopic bone defects. We have shown earlier that the intermixing of the recombinant human transforming growth factor-β1 (rhTGF-β1) in hardening calcium phosphate cement stimulated osteoblastic differentiation of rat primary bone cells in vitro. The aim of the present study was to examine whether the similar enrichment with rhTGF-β1 affects the replacement of calcium phosphate cement by bone (osteotransduction) in calvarial critical size defects (csd) of adult rats. Two bone defects of 5 mm diameter were created bilaterally in each skull of 10 adult male rats. Both defects were filled with 53 mg of calcium phosphate cement without rhTGF-β1 (control) at one side, and with 10 or 20 ng rhTGF-β1 at the other side. After 8 weeks, defects with surrounding skull were analysed histologically and histomorphometrically. The addition of rhTGF-β1 in the cement increased the amount of bone in rat skull defects. This finding coincidences with our in vitro observations, that intermixing of rhTGF-β1 in calcium phosphate cement stimulates bone cell differentiation. Addition of rhTGF-β1 stimulated bone formation as indicated by an increased bone volume of 50% and an increased bone/cement contact of 65%, in comparison to control defects with cement without rhTGF-β1. In addition, rhTGF-β1 reduced the remaining volume of cement, by 11% at 10 ng rhTGF-β1, and by 20% at 20 ng rhTGF-β1 in the cement. Defect closure was not affected. We conclude that the intermixing of rhTGF-β1 in a fast-setting calcium phosphate cement stimulates bone growth and the osteotransduction of the cement. For bone regeneration procedures around endosseous implants, calcium phosphate cement with rhTGF-β1 might be an appropriate combination for early osseointegration and implant use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0501.2001.120609.x
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  • 4
    Electronic Resource
    Electronic Resource
    Fate of monocortical bone blocks grafted in the human maxilla: a histological and histomorphometric study (2003)
    Oxford, UK : Munksgaard International Publishers
    Clinical oral implants research 14 (2003), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Local bone defects in the anterior maxilla are commonly grafted with monocortical blocks of autologous bone in order to restore the defect site prior to the placement of dental implants. Increasing evidence suggests that osteocytes are involved in the control of bone remodelling and thus may be important for optimalisation of bone structure around implants, and thus for implant osseointegration. However, it is not well known whether osteocytes will survive when bone blocks are grafted into defects. We grafted 19 patients with monocortical bone blocks derived from the symphysis, to the defect site in the maxillary alveolar process. The bone grafts were left to heal for times varying from 2.5 to 7 months. During implant installation, bone biopsies were removed using a trephine burr, and processed for hard tissue histology. Bone histology and histomorphometry were then carried out in order to gain insight into the density, viability and remodelling of the graft. Clinically, all the bone grafts were successful, with no implant failures, and little resorption was seen. Histologically, bone volume expressed as percentage of tissue volume at the implant site varied from 27% to 57% with an overall average of 41%. Bone fields with empty osteocyte lacunae were observed and measured. The amount of this so-called nonvital bone (NVB) varied between 1% and 34% of the total tissue volume. The amount of NVB decreased significantly with the time of healing. The data suggest that the majority of the osteocytes of the monocortical bone do not survive grafting. The results indicate that the NVB is progressively remodelled into new vital bone 7 months after grafting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0905-7161.2003.00967.x
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  • 5
    Electronic Resource
    Electronic Resource
    Bacteroides gingivalis stimulates bone resorption via interleukin-1 production by mononuclear cells The relative role for B. gingivalis endotoxin (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of clinical periodontology 17 (1990), S. 0 
    Details
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract. Supernatants of human peripheral blood mononuclear cells cultured in the presence of B. gingivalis, showed a strong osteoclast stimulating activity as measured by 45Ca release from fetal mouse long bones in vitro. These supernatants also contained a high concentration of bioactive and immunoreactive interleukin-l (IL-1), but tumor necrosis factor (TNFa), another osteoclast-activating cytokine, was not detected. Osteoclast activation by the supernatants was inhibited by an antibody against IL-1. whereas ultrapure human IL-1 mimicked the effect of the supernatant. The ability of B. gingivalis to induce IL-1 and OAF production was heat sensitive, as 20 min heating of the bacteria at 120°C caused a 50% loss of activity. In addition, purified B. gingivalis lipopolysaccharide (LPS) had little IL-1 inducing capacity, compared with LPS of Escherichia coli. These data suggest that human peripheral blood cells confronted with B. gingivalis produce large amounts of IL-1 which has strong osteoclast stimulating activity. However, in contrast with E. coli LPS, B. gingivalis LPS does not seem to be the major inducing agent. Thus other bacterial components must be responsible for the observed IL-1 and OAF induction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-051X.1990.tb02338.x
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  • 6
    Electronic Resource
    Electronic Resource
    Histological observations on biopsies harvested following sinus floor elevation using a bioactive glass material of narrow size range (2000)
    Copenhagen : Munksgaard International Publishers
    Clinical oral implants research 11 (2000), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We evaluated the bone augmenting capacity of bioactive glass particles, size range 300–355 μm (BG-particles), in human sinus floor elevations using histomorphometrical methods. A total of 10 patients underwent bilateral grafting, using a 1:1 mixture of autogenous bone particles (from iliac crest) and BG-particles at one side (experimental side), and bone particles only at the other side (control side, split mouth design). A total of 72 bone biopsies were taken at the time of fixture installation; that is, 3 patients at 4 months, 3 at 5 months and 3 at 6 months after grafting and 1 patient at 16 months (when she presented again). In each case 6 biopsies were taken, 3 left and 3 right. Histomorphometry showed that in grafts at control sides, trabecular bone was present after 4 months, comprising almost 41% of the tissue volume. This bone contained viable osteocytes and was of mature lamellar type and showed a mature histological appearance. Bone volume continued to increase slightly, to 42% at 5 months, 44% at 6 months and 45% at 16 months. The graft volume at experimental sides consisted at 4 months for 28% of woven and some lamellar bone, and increased to 35% at 5 months and 38% at 6 months, when mainly lamellar bone was found. At 16 months a lamellar bone volume of 45% was found. The BG-particles transformed and became excavated with time, starting at 4 months, and their centers gradually filled with bone tissue. All BG-particles had disappeared by resorption at 16 months after grafting and had been replaced by bone tissue. Parameters of bone turnover (% osteoid surface, % resorption surface, mineral apposition rate as measured by tetracycline labeling) indicated that bone remodeling was very active at both sides, during more than 6 months, despite the mature histological appearance of the bone tissue. From these histological observations, we conclude that a 1:1 mixture of autogenous bone/BG-particles seems a promising alternative to autogenous bone only, when low amounts of bone tissue are available for sinus augmentation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0501.2000.011004334.x
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  • 7
    Electronic Resource
    Electronic Resource
    High concentrations of bioactive glass material (BioGran®) vs. autogenous bone for sinus floor elevation (2002)
    Oxford, UK : Blackwell Science, Ltd
    Clinical oral implants research 13 (2002), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In this study, high concentrations of bioactive glass (BG) particles were compared with autogenous bone in their capacity to augment maxillary bone when grafted in the human sinus floor using a split mouth design. Three female patients with severe maxillary atrophy underwent bilateral sinus floor elevation and bone grafting using 80–100% BG particles (300–355 μm in size) mixed with 20% to 0% iliac crest bone particles at one (experimental) side, and 100% iliac crest derived bone particles at the other (control) side. A total of 22 bone biopsies was taken at the time of fixture installation; that is, at 4, 6 and 15 months after grafting, and processed for histology and histomorphometry. At the control (autogenous bone) sides, trabecular bone amounted to 39% of the biopsy volume in the graft (site) at 4 months, almost 41% at 6 months, and 42% at 15 months. This bone contained viable osteocytes and was mostly of mature, lamellar type. At the experimental (BG particles) sides, the graft consisted of 27% of mostly woven (and some lamellar) bone at 4 months, 36% (woven and lamellar) bone at 6 months, and 39% (mainly lamellar) bone at 15 months. The grafted BG particles started to excavate at 4 months and their centers gradually filled with bone tissue. As a consequence, the volume of BG particles in the biopsy decreased from 29% at 4 months to 15% at 6 months and 8% at 15 months. The BG particles appeared to resorb within 1–2 years by dissolution rather than by osteoclastic activity. Parameters for bone turnover (% osteoid surface, % resorption surface) indicated that bone remodeling was very active at both experimental and control sides, during more than 6 months. These results suggest that mixtures of mainly (80–90%) BG particles and some (10–20%) autogenous bone are effective for bone regeneration in the augmented sinus offer 6 months healing time, while about 12 months healing time is needed for 100% BG particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0501.2002.130412.x
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  • 8
    Electronic Resource
    Electronic Resource
    Osteoblast and osteoclast precursors in primary cultures of calvarial bone cells (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 214 (1986), S. 32-40 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Bone cells obtained by digestion of fetal mouse or chicken calvaria were tested for their ability to form or resorb bone in vitro. The isolated cells were precultured for 6 days and subsequently cocultured for 11 days with periosteum-free noninvaded fetal mouse long bone rudiments. Bone formation and resorption during coculture were evaluated by histology and 45Ca release from prelabeled bones. The calvarial origin of cells in cocultures was traced by labeling the cells with 3H-thymidine before coculture, followed by autoradiography.Many osteoblasts and osteoclasts as well as fibroblasts developed from mouse periosteal cells released late in the sequential digestion procedure and previously denoted as “osteoblastlike” (BL). No or few osteoblasts and osteoclasts but many fibroblasts developed from early released cell fractions that have previously been denoted as “osteoclastlike” (CL).Only osteoblasts and fibroblasts but not osteoclasts developed from chicken calvarial cell fractions. The osteoblasts developed primarily from cell fractions from the inner layer of the periosteum, previously denoted as “osteoblastlike” (OB). Cells obtained from the outer layer of the periosteum (PF) gave rise mainly to fibroblasts.These studies show that osteoblast and osteoclast precursor cells are maintained in monolayer cultures of periosteal cell fractions. However, sequential digestion of mouse calvaria does not lead to separation of the two types of bone cells. Rather, osteoclast and osteoblast precursors are released jointly, from the periosteal cell layers closest to the bone surface. In the chicken cell fractions osteoclast precursors are absent after preculture, resulting in a more homogeneous population of osteoblast and fibroblast but not osteoclast precursors.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092140106
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  • 9
    Electronic Resource
    Electronic Resource
    Function of osteocytes in bone (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 55 (1994), S. 287-299 
    Details
    ISSN: 0730-2312
    Keywords: osteocyte ; gap junction ; cytoskeleton ; extracellular matrix ; osteocytic osteolysis ; bone membrane ; functional adaptation ; mechanical loading ; strain ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Although the structural design of cellular bone (i.e., bone containing osteocytes that are regularly spaced throughout the bone matrix) dates back to the first occurrence of bone as a tissue in evolution, and although osteocytes represent the most abundant cell type of bone, we know as yet little about the role of the osteocyte in bone metabolism. Osteocytes descend from osteoblasts. They are formed by the incorporation of osteoblasts into the bone matrix. Osteocytes remain in contact with each other and with cells on the bone surface via gap junction-coupled cell processes passing through the matrix via small channels, the canaliculi, that connect the cell body-containing lacunae with each other and with the outside world. During differentiation from osteoblast to mature osteocyte the cells lose a large part of their cell organelles. Their cell processes are packed with microfilaments. In this review we discuss the various theories on osteocyte function that have taken in consideration these special features of osteocytes. These are (1) osteocytes are actively involved in bone turnover; (2) the osteocyte network is through its large cell-matrix contact surface involved in ion exchange; and (3) osteocytes are the mechanosensory cells of bone and play a pivotal role in functional adaptation of bone. In our opinion, especially the last theory offers an exciting concept for which some biomechanical, biochemical, and cell biological evidence is already available and which fully warrants further investigations. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240550304
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  • 10
    Electronic Resource
    Electronic Resource
    Mechanical loading stimulates the release of transforming growth factor-β activity by cultured mouse calvariae and periosteal cells (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 163 (1995), S. 115-119 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have shown earlier that mechanical stimulation by intermittent hydrostatic compression (IHC) inhibits bone resorption and stimulates bone formation in cultured fetal mouse calvariae (Klein-Nulend et al., 1986, Arthritis Rheum., 29:1002-1009). The production of soluble bone factors by such calvariae is also modified (Klein-Nulend et al., 1993, Cell Tissue Res., 271:513-517). Transforming growth factor-β (TGF-β) is an important local regulator of bone metabolism and is produced by osteoblasts. In this study, the release of TGF-β activity as a result of mechanical stress was examined in organ cultures of neonatal mouse calvariae, in primary cultures of calvariae-derived osteoprogenitor (OPR) cells, and in more differentiated osteoblastic (OB) cells. Whole calvariae and calvariaederived cells were cultured in the presence or absence of IHC for 1-7 days and medium concentrations of active as well as total TGF-β were measured using a bioassay. IHC (maximum 13 kPa, maximal pressure rate 32.5 kPa/sec) was generated by intermittently (0.3 Hz) compressing the gas phase above the cultures. We found that mechanical loading by IHC stimulated the release of TGF-β activity from cultured calvariae by twofold after 1 day. IHC also stimulated the release of TGF-β activity from calvariae-derived cells after 1 and 3 days. The absolute amounts of TGF-β activity released were lower in OPR cells than in OB cells, but the stimulatory effect of IHC was greater in OPR cells. Total TGF-β (active and bound) released into the medium was not affected by IHC. IHC did not change the dry weight of the organ cultures, nor the DNA or protein content of the cell cultures. These data show that mechanical perturbation of bone cells, particularly OPR cells, enhances the activation of released TGF-β. We conclude that modulation of TGF-β metabolism may be part of the response of bone tissue to mechanical stress. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041630113
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