Enhancement of Bone Formation by Bone Morphogenetic Protein-2 During Alveolar Distraction: An Experimental Study in Sheep
Department of Oral and Maxillofacial Surgery, Rambam Medical Center, Haifa, Israel. Journal of Periodontology
(Impact Factor: 2.71).
11/2004; 75(11):1524-31. DOI: 10.1902/jop.2004.75.11.1524
The purpose of this study was to perform alveolar ridge augmentation by distraction osteogenesis (DO) and to enhance bone regeneration through the use of recombinant human bone morphogenetic protein-2 (rhBMP-2), followed by implant placement.
Alveolar segmental osteotomy was performed in the mandible of 10 sheep followed by placement of 1.5 mm alveolar distraction devices. The study group was injected on the fifth day of distraction with a single dose of 10 microg rhBMP-2. Only distraction was performed in the control group.
A mean alveolar augmentation of 12 mm was achieved. After 12 weeks of consolidation, the distraction devices were removed and biopsies were taken for histological and immunohistochemical characterization and morphometry of the newly formed bone. Titanium threaded cylindrical implants were then placed in the newly augmented bone. Radiological evaluation showed lifting of the transport segment and integration of the implants within both the transport segment and the regenerated bone. The histological study demonstrated that the association of DO and BMP resulted in increased trabecular bone size and volume (32.2%+/-0.95% versus 18.6%+/-0.71%; P <1 x 10(-17) after 24 days of lengthening and 63.8%+/-1.89% versus 42.5%+/-1.33%; P<1 x 10(-15) after 12 weeks of consolidation) and increased numbers of proliferating cell nuclear antigen stained cells (0.7+/-0.04 versus 0.47+/-0.04; P<1 x 10(-10)) compared with the DO only group.
Alveolar distraction augments atrophic alveolar ridge and creates new bone that permits implant placement. rhBMP-2 enhances bone quality and may shorten the consolidation period of distraction allowing for earlier implant placement.
Available from: Yoav Leiser
- "There are complex interactions between the osteoblasts, the bone-forming cells, and other cells present within the bone microenvironment, particularly vascular endothelial cells that may be pivotal members of a complex interactive communication network in bone.14–17 Past studies have implicated a number of cytokines that are involved in the regulation of bone synthesis and turnover.15,16,18,19 The gene regulation of numerous cytokines [including transforming growth factor (TGF)-β, bone morphogenetic protein (BMP), insulin-like growth factor (IGF)-1, and fibroblast growth factor (FGF)-2] and extracellular matrix proteins (osteonectin and osteopontin) during distraction osteogenesis have been best characterized and are discussed later in this article. "
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ABSTRACT: Gradual bone lengthening using distraction osteogenesis principles is the gold standard for the treatment of hypoplastic facial bones. However, the long treatment time is a major disadvantage of the lengthening procedures. The aim of this study is to review the current literature and summarize the cellular and molecular events occurring during membranous craniofacial distraction osteogenesis. Mechanical stimulation by distraction induces biological responses of skeletal regeneration that is accomplished by a cascade of biological processes that may include differentiation of pluripotential tissue, angiogenesis, osteogenesis, mineralization, and remodeling. There are complex interactions between bone-forming osteoblasts and other cells present within the bone microenvironment, particularly vascular endothelial cells that may be pivotal members of a complex interactive communication network in bone. Studies have implicated number of cytokines that are intimately involved in the regulation of bone synthesis and turnover. The gene regulation of numerous cytokines (transforming growth factor-β, bone morphogenetic proteins, insulin-like growth factor-1, and fibroblast growth factor-2) and extracellular matrix proteins (osteonectin, osteopontin) during distraction osteogenesis has been best characterized and discussed. Understanding the biomolecular mechanisms that mediate membranous distraction osteogenesis may guide the development of targeted strategies designed to improve distraction osteogenesis and accelerate bone regeneration that may lead to shorten the treatment duration.
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ABSTRACT: A neural network data fusion decision system and the accompanying
experimental results obtained from joint sensor data are presented. The
decisions include detection and correct classification of space object
maneuvers simultaneously observed by two radars of different aspect,
frequency, and resolution. The system consists of a statistically-based
adaptive preprocessor for each sensor, followed by a highly parallel
neural network for associating the preprocessor outputs with the
appropriate decisions. The preprocessing approach, supported by a signal
decomposition theorem, recursively models the detrended sensor data as
an autoregressive process of sufficiently high order. This approach also
accommodates nonstationary data by incorporating an
information-theoretic transition detector which identifies the segments
of near-stationary data. Together, feature vectors are produced over
near-stationary segments of data which are scale invariant, translation
invariant, and normalized and represent sufficient statistics.
Subsequently, the feature vectors arising from the sensor preprocessors
are collectively associated with the correct output decision. The
association is conducted by a multilayer perceptron neural network
associative memory employing a modified learning algorithm which
converges at a rate comparable to that of conventional algorithms, yet
requires less computation
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ABSTRACT: The healing period of bone-implant osseointegration usually varies from 3 to 6 months or even longer. Failure may occur during this time. This study aimed to investigate whether osseointegration of dental implants can be enhanced by the combination of growth factors.
Sixty-four implants were coated with polylactic acid and divided into four groups. Group I was applied with 1.0 mg recombinant human bone morphogenetic protein-2 (rhBMP-2) and 200 microg recombinant human basic fibroblast growth factor (rhbFGF), group II with 1.0 mg rhBMP-2 and 250 mug recombinant human insulin-like growth factor-I (rhIGF-I), group III with 1.0 mg rhBMP-2, and group IV without growth factors as control. In total, 16 rabbits were used, and two osteotomies were drilled on each side of the femur, in which four different groups were randomly placed. Four weeks after implanting, 20 mg calcein green/kg body weight was administered intravenously, and 8 weeks after implanting, 20 mg alizarin/kg body weight was administered intravenously. Twelve weeks after implanting, the animals were sacrificed. The block of bone with implants was embedded in methylmethacrylate and sectioned, and the percentage of new bone surrounding the implant was analyzed by confocal laser scanning microscopy.
There was a statistical difference in bone formation between rhBMP-2-applied groups and the non-applied group at 4 or 8 weeks, and no significant difference between groups I and II (although bone formation in group II was greater than that in group I at 4 weeks). The bone formation in group II was greater than that in group III at 4 or 8 weeks. The formed bone in group I was also greater than the one in group III at 8 weeks, but there was no difference at 4 weeks.
rhBMP-2 could increase new bone formation, and it acted synergistically with rhbFGF and rhIGF-I to improve bone-implant osseointegration. The combination of rhBMP-2 and rhbFGF (group 1) showed faster growth of new bone than other groups at 8 months.
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