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1.
Oral Dis ; 20(1): 10-6, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23679579

RESUMO

All cells and organisms across the evolutionary spectrum, from the most primitive to the most complex, are mechanosensitive. As the cytoskeleton is a key in controlling the normal basal prestress of cells and therefore is involved in virtually all physiological cellular processes, abnormalities in this essential cellular characteristic may result in diseases. Indeed, many diseases have now been associated with abnormalities in cytoskeletal and nucleoskeletal proteins. We propose that adult periodontitis is, at least in part, such a cytoskeletal disease. It is well established that adult periodontitis starts by bacterial invasion at the interface between the tooth surface and marginal gingiva that induces a local inflammatory response. The inflammatory cells release metalloproteinases which degrade gingival collagenous fibrous tissue and loss of local tissue integrity that reduces the normal prestressed cell-extracellular matrix network. This is a major signaling trigger that induces a local and rapid release of ATP, which then activates P2X receptors and stimulates a calcium influx, further activating osteoclastic resorption of the alveolar bone. As periodontitis is a chronic disease, it seems reasonable to suggest that agents that maintain cytoskeletal tensegrity, for example, inhibitors of ATP receptors, may diminish the bone loss and may have a role in future periodontal therapy.


Assuntos
Periodontite Crônica/etiologia , Proteínas do Citoesqueleto , Reabsorção Óssea/etiologia , Periodontite Crônica/complicações , Periodontite Crônica/patologia , Gengiva/patologia , Humanos
2.
Orthod Craniofac Res ; 16(3): 161-8, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23323644

RESUMO

OBJECTIVES: Accelerated orthodontic tooth movement is triggered by procedures that include mucoperiosteum flap surgery and surgical scarring of cortical bone. Our aim was to test whether fiberotomy by itself will accelerate orthodontic tooth movement and diminish relapse. MATERIALS AND METHODS: In 34 Wistar rats, alveolar bone resorption and molar tooth movement were measured after fiberotomy, apical full-thickness flap without detachment of gingiva from the roots, or no surgery. Orthodontic appliance was installed at time of surgery and activated for 14 days, generating movement of the first maxillary molar buccal and then removed. RESULTS: Percent of sections in which alveolar bone resorption was detected was significantly higher (p < 0.05) after fiberotomy (27%) in comparison with apical flap surgery (12%) or no surgery (6%), after 30 days. Also, at the end of active phase, the molar moved significantly faster (p < 0.01) and twice the distance after fiberotomy (0.54 ± 0.33) in comparison with apical surgery (0.26 ± 0.12) or no surgery (0.3 ± 0.09). Sixteen days after the appliance was removed, only 12% relapse was recorded in the fiberotomy group, while almost total relapse in other two groups. CONCLUSION: We conclude that fiberotomy solely accelerated orthodontic tooth movement and diminished relapse.


Assuntos
Gengiva/cirurgia , Técnicas de Movimentação Dentária/métodos , Perda do Osso Alveolar/patologia , Processo Alveolar/patologia , Animais , Remodelação Óssea/fisiologia , Tecido Conjuntivo/cirurgia , Masculino , Microrradiografia , Modelos Animais , Dente Molar/patologia , Periósteo/cirurgia , Ratos , Ratos Wistar , Recidiva , Retalhos Cirúrgicos/cirurgia , Fatores de Tempo , Técnicas de Movimentação Dentária/instrumentação
3.
J Orthop Res ; 28(5): 664-70, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-19918912

RESUMO

Most bone regeneration experimental models that test bone-derived matrices take place in conjunction with the native bone. Here, we compared the relative effectiveness of bone matrix components on bone-marrow-directed osteogenesis in an ectopic model. Cortical bone cylinders consisted of diaphysis of DA rat femurs. They were either demineralized (DBM), deproteinized (HABM), or nontreated (MBM). Fresh bone marrow was placed into cylinders and implanted at subcutaneous thoracic sites of 2-month-old DA rats. At designated times the cylinders were surgically removed from the animals. Microradiographs of DBM and histology of DBM and MBM cylinders demonstrated progressive increase in mineralized bone volume and its trabecular configuration. Bone filled the inner volume of DBM and MBM cylinders within 4 weeks, while in HABM cylinders mostly granulation tissue developed. In the DBM cylinders cartilage deposited within 10 days, while in the MBM cylinders bone was directly deposited. As early as day 3 after marrow transplantation, marrow cells interacting with DBM increased significantly the genes that express the cartilage and the bone phenotype. In conclusion, organic components of bone are needed for marrow-directed osteogenesis.


Assuntos
Medula Óssea/fisiologia , Diáfises/fisiologia , Fêmur/fisiologia , Osteogênese/fisiologia , Regeneração/fisiologia , Animais , Biomarcadores , Técnica de Desmineralização Óssea , Medula Óssea/diagnóstico por imagem , Células da Medula Óssea/citologia , Células da Medula Óssea/fisiologia , Transplante de Medula Óssea , Cartilagem/fisiologia , Comunicação Celular/fisiologia , Diáfises/diagnóstico por imagem , Feminino , Fêmur/citologia , Fêmur/diagnóstico por imagem , Furanos , Expressão Gênica/fisiologia , Hematopoese/fisiologia , Modelos Animais , Osteoblastos/citologia , Osteoblastos/fisiologia , Radiografia , Ratos , Tiofenos
4.
Crit Rev Eukaryot Gene Expr ; 17(2): 87-101, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17725482

RESUMO

Regeneration is the ability of cells to restore lost or damaged tissues and organs in adults by pathways that mimic developmental processes. Although many of the molecular mechanisms that control cellular differentiation and growth during embryogenesis recur during fracture healing, these processes take place in a postnatal environment that is unique and distinct from those that exist during embryogenesis. Bone tissue has a remarkable capacity of regeneration without scarring. This article highlights central biological and molecular processes that are crucial in embryonic bone development. Several animal bone regeneration models are described. The patterns of gene expression during the regeneration process in the different models are reviewed. Exploring the similarities and the differences in the molecular processes in different models will contribute to the understanding of their potential in the processes of bone regeneration and tissue engineering.


Assuntos
Regeneração Óssea/fisiologia , Animais , Desenvolvimento Ósseo/genética , Desenvolvimento Ósseo/fisiologia , Regeneração Óssea/genética , Cervos , Feminino , Consolidação da Fratura/genética , Consolidação da Fratura/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Substâncias de Crescimento/genética , Substâncias de Crescimento/fisiologia , Humanos , Masculino , Modelos Animais , Ratos , Transdução de Sinais/fisiologia
5.
J Dent Res ; 86(2): 181-5, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17251520

RESUMO

Several studies have shown that surgical detachment of marginal gingiva close to the cervical cementum of molar teeth in a rat mandible is a distinct stimulus for alveolar bone resorption. Recently, we found that P2X4, an ATP-receptor, is significantly up-regulated in marginal gingival cells soon after surgery. We hypothesized that local release of ATP signaling through P2X4 elicits activation of osteoclasts on the alveolar bone surface. In this study, we identified intense immunoreactivity of gingival fibroblasts to P2X4-specific antibodies and a 6.4-fold increase in expression by real-time RT-PCR. Moreover, a single local application, at the time of surgery, of Apyrase (which degrades ATP) or Coomassie Brilliant Blue (an antagonist of purinoreceptors) significantly reduced alveolar bone loss. We propose that ATP flowing from cells after surgery can directly activate P2X4 receptors in the sensor cells of marginal gingiva through Ca(2+) signaling, or by direct activation of osteoclasts on the bone surface.


Assuntos
Perda do Osso Alveolar/etiologia , Perda do Osso Alveolar/metabolismo , Gengiva/metabolismo , Gengivectomia/efeitos adversos , Receptores Purinérgicos P2/biossíntese , Trifosfato de Adenosina/antagonistas & inibidores , Trifosfato de Adenosina/fisiologia , Perda do Osso Alveolar/prevenção & controle , Análise de Variância , Animais , Apirase/fisiologia , Fibroblastos/metabolismo , Gengiva/citologia , Indicadores e Reagentes/farmacologia , Osteoclastos/efeitos dos fármacos , Ratos , Ratos Wistar , Receptores Purinérgicos P2X4 , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Corantes de Rosanilina/farmacologia , Regulação para Cima
6.
J Oral Rehabil ; 33(8): 619-924, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16856960

RESUMO

Low intensity lasers have been used by clinicians to improve healing and reduce pain in humans. Lasing also results in new bone formation around hydroxyapatite implants and a significant increase in the total bone area. However, the exact mechanism of cell biostimulation by laser is still unclear. This study biochemically assessed the effects of low intensity laser (Gallium-Arsenide) using 4 and 22.4 mW cm(-2) power density on the bone healing process after surgically creating bony cavities in rat mandibles. Rats (n = 24) were divided into two groups each treated with specific energy, 4 or 22.4 mW cm(-2), for 3 min each day post-surgery. Surgical cavities were created on both sides of the mandible: the left served as an untreated control, the right was treated with laser. All rats were sacrificed after 1, 2 and 4 weeks of treatment. In the newly formed callus, accumulation of radiocalcium and alkaline phosphatase activity was measured to indicate osteogenic activity. One-way anova with repeated measures showed that the low intensity laser using 4 mW cm(-2) power density significantly increased radiocalcium accumulation from 2 weeks post-surgery, whereas 22.4 mW cm(-2) had no effect. No changes were noted in the activity of alkaline phosphatase with the laser treatment. These results suggest that laser therapy of low power density is effective on the bone healing process in artificially created osseous cavities by affecting calcium transport during new bone formation.


Assuntos
Terapia com Luz de Baixa Intensidade , Mandíbula/cirurgia , Cicatrização/efeitos da radiação , Fosfatase Alcalina/metabolismo , Animais , Regeneração Óssea/efeitos da radiação , Calcificação Fisiológica/efeitos da radiação , Radioisótopos de Cálcio , Masculino , Mandíbula/fisiopatologia , Osteogênese/efeitos da radiação , Ratos , Ratos Wistar
7.
J Periodontol ; 74(7): 1038-42, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12931767

RESUMO

BACKGROUND: Recent animal studies have shown that a combination of chemically-modified tetracyclines together with bisphosphonates, when delivered systemically, are synergistically effective in suppressing periodontal bone loss. In the present study, we explored the combined efficacy of local delivery of alendronate and tetracyclines in reducing alveolar bone loss. METHODS: Eighty-six (86) male Wistar rats were used in these experiments. The flap was elevated using a special periosteal elevator, on both sides of the mandible, as described previously. A gelfoam pellet containing the drugs was applied between the alveolar bone and the mucoperiosteal flap, according to the experimental protocol. The rats were divided into 5 treatment groups: 1) alendronate; 2) doxycycline hyclate 10% (DOXY); 3) tetracycline hydrochloride 1% (TET); 4) alendronate + DOXY; and 5) alendronate + TET. In the operated control sites (C), saline was applied. The rats were sacrificed 21 days following the flap procedure. Sections of the mandibles (1.5 mm), in a buccal-lingual direction, underwent microradiography and were analyzed for bone loss. RESULTS: DOXY alone was most effective in reducing bone loss. Alendronate was also effective in reducing bone loss as shown in previous reports. TET did not reduce bone loss significantly when used alone. In combination with alendronate TET was synergistically effective. The combined local treatment of alendronate + DOXY showed no additive effect. CONCLUSIONS: In the present study, we found that tetracyclines can be most effective in reducing alveolar bone loss when applied locally. The combined local treatment of alendronate and tetracycline may have a synergistic effect.


Assuntos
Alendronato/uso terapêutico , Perda do Osso Alveolar/prevenção & controle , Antibacterianos/uso terapêutico , Doxiciclina/uso terapêutico , Tetraciclina/uso terapêutico , Administração Tópica , Alendronato/administração & dosagem , Processo Alveolar/efeitos dos fármacos , Animais , Antibacterianos/administração & dosagem , Reabsorção Óssea/prevenção & controle , Doxiciclina/administração & dosagem , Portadores de Fármacos , Combinação de Medicamentos , Sinergismo Farmacológico , Esponja de Gelatina Absorvível , Masculino , Mandíbula/efeitos dos fármacos , Microrradiografia , Ratos , Ratos Wistar , Retalhos Cirúrgicos , Tetraciclina/administração & dosagem
8.
J Cell Biochem ; 84(3): 509-19, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-11813256

RESUMO

Chick limb-bud mesenchymal cells, plated in micromass culture, differentiate in vitro to form a cartilaginous structure analogous to the epiphyseal growth plate. When inorganic phosphate, Pi, is included in the medium such that the total Pi concentration is 4 mM, apatite mineral precipitates around the "hypertrophic" chondrocytes. These hypertrophic chondrocytes are characterized by their increased expression of type X collagen, alkaline phosphatase activity, and apoptosis, as well as by the ability of their extracellular matrices to support mineral deposition. Under standard mineralizing conditions (0.8 x 10(6)cells/micromass; 4 mM Pi, 1.3 mM Ca(2+), 10% FCS, and antibiotics) mineralization does not commence until day 14-16. Based on the ability of bone morphogenic protein 6 (BMP-6) to stimulate chondrocyte maturation in other systems, 100 ng/ml BMP-6 was added to chick limb-bud mesenchymal cell cultures 2 and 5 days after plating, and the effects of this addition on mineral accretion and the characteristics of the mineral and matrix determined. Addition of BMP-6 accelerated the differentiation of the mesenchymal cells to hypertrophic chondrocytes. In the presence of BMP-6 added on both days 2 and 5, mineralization (assessed on basis of (45)Ca uptake) commenced by day 12. Fourier transform infrared imaging (FTIRI) was used to monitor the mineral content and mineral crystallinity as a function of time from day 9 to 21 in cultures with and without exogenous BMP-6. While BMP-6 accelerated the rate of mineral accretion, and the crystals that were formed in the BMP-6 cultures were initially more mature, by day 21 the crystal size distribution in experimental and control cultures were not significantly different. This study, the first to report the detailed application of FTIRI to cell cultures, indicates the importance of the extracellular matrix in the control of crystal maturation.


Assuntos
Proteínas Morfogenéticas Ósseas/farmacologia , Calcificação Fisiológica/efeitos dos fármacos , Embrião de Galinha/crescimento & desenvolvimento , Condrogênese/efeitos dos fármacos , Extremidades/embriologia , Fosfatase Alcalina/análise , Fosfatase Alcalina/imunologia , Animais , Biomarcadores/análise , Proteína Morfogenética Óssea 6 , Cálcio/metabolismo , Diferenciação Celular , Células Cultivadas , Embrião de Galinha/citologia , Embrião de Galinha/efeitos dos fármacos , Condrócitos/fisiologia , Colágeno Tipo X/imunologia , Colágeno Tipo X/metabolismo , Matriz Extracelular/fisiologia , Imuno-Histoquímica , Cinética , Mesoderma/efeitos dos fármacos , Mesoderma/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier
9.
J Periodontol ; 72(10): 1348-53, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11699476

RESUMO

BACKGROUND: In several publications, we have reported that a distinct resorptive phase of alveolar bone developed during 3 weeks following elevation of a mucoperiosteal flap in rats by a coronal surgical approach. In the present study, we compared the alveolar bone loss after mucoperiosteal flap surgery by a coronal approach (COR) to a surgical approach incising the mucosa close to the tooth apices and separating the mucoperiosteum toward the tooth crown (apical approach, AP). METHODS: Eighteen Wistar rats were divided into 2 experimental groups; each group consisted of 9 rats. In the first group, COR was performed on both buccal and lingual aspects on the right side of the rat mandible, while the left side served as a sham-operated control. In the second experimental group, AP was performed. RESULTS: In the AP group, the outer aspect (buccal or lingual) of the alveolar bone was slightly resorbed usually at the level where the mucosa was incised. In many sections, extensive modeling of new trabecular bone was seen, coronal to the surgical incision. On the contrary, the coronal surgical approach revealed an extensive resorptive phase, mainly of the periodontal aspect of the alveolar bone. CONCLUSIONS: The results of this study show that periodontal surgery by a coronal surgical approach stimulates a burst of remodeling of the alveolar bone in a very specific pattern.


Assuntos
Perda do Osso Alveolar/etiologia , Mandíbula/cirurgia , Mucosa Bucal/transplante , Periósteo/transplante , Retalhos Cirúrgicos/efeitos adversos , Perda do Osso Alveolar/patologia , Processo Alveolar/patologia , Animais , Remodelação Óssea/fisiologia , Distribuição de Qui-Quadrado , Colágeno , Corantes , Corantes Fluorescentes , Gengivectomia , Mandíbula/patologia , Microrradiografia , Osteoclastos/patologia , Osteócitos/patologia , Ligamento Periodontal/patologia , Ratos , Ratos Wistar , Estatística como Assunto , Retalhos Cirúrgicos/classificação , Cicatrização
10.
J Periodontol ; 71(10): 1607-12, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11063394

RESUMO

BACKGROUND: Periodontal surgery stimulates osteoclast activity, leading to varying amounts of alveolar crest loss. We have established that topical application of 20 mg/ml of alendronate placed at the surgical mucoperiosteal site produced a striking reduction of alveolar bone loss in the rat model. The aim of this investigation was to examine the antiresorptive efficacy of 3 novel bisacylphosphonates topically delivered at the surgical site, in comparison to alendronate and etidronate which are in clinical use. METHODS: Mucoperiosteal flap (MF) surgery was performed on the buccal and lingual aspects next to molars on both sides of the rat mandible. A gelatin sponge soaked in the bisphosphonate solution prepared by dissolving 20 mg of the bisphosphonate (alendronate, etidronate, VS-5, VS-6, ISA-13, SuBP) in 1 ml of saline was applied to exposed bone on the right side of the mandible (experimental, MF + BPs ) and the left side was treated with saline only (control, MF + S). Sections were evaluated for bone loss using microradiography pattern and amount. RESULTS: The 3 novel bisacylphosphonates, VS-5 VS-6, and ISA-13 were more effective than etidronate, and less effective than alendronate. The most effective among this group was ISA-13 followed by VS-5 and VS-6. CONCLUSION: We conclude that ISA-13-like alendronate is effective in reducing alveolar bone loss when delivered at surgical sites. Since ISA-13 is well absorbed through mucose tissues, we suggest that ISA-13 efficacy on reducing bone loss should be tested by its application on the mucosal tissue.


Assuntos
Perda do Osso Alveolar/prevenção & controle , Difosfonatos/administração & dosagem , Modelos Animais de Doenças , Compostos Heterocíclicos/administração & dosagem , Administração Tópica , Alendronato/administração & dosagem , Perda do Osso Alveolar/diagnóstico por imagem , Processo Alveolar/diagnóstico por imagem , Processo Alveolar/efeitos dos fármacos , Animais , Distribuição de Qui-Quadrado , Avaliação Pré-Clínica de Medicamentos , Ácido Etidrônico/administração & dosagem , Microrradiografia , Análise Multivariada , Ratos , Ratos Wistar
11.
J Periodontol ; 71(8): 1236-40, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10972639

RESUMO

BACKGROUND: Mucoperiosteal flaps are used to access bone and root surfaces for debridement, pocket elimination, management of periodontal defects, and in regenerative procedures, as well as in implant surgery. Many reports show that periodontal surgery stimulates osteoclast activity with varying amounts of alveolar bone loss. Alendronate given intravenously significantly reduced alveolar bone loss in mucoperiosteal flap procedures. In the present study, we explored the effectiveness of different concentrations of alendronate, delivered at the surgical site at the time of surgery, in distant delivery in reducing alveolar bone loss. METHODS: Following elevation of a mucoperiosteal flap next to molars of the rat mandible, a gelatin sponge soaked with different concentrations of alendronate (0, 1, 5, 20, or 40 mg/ml; experiment A) was applied to exposed bone on the experimental side. In the second group (experiment B), alendronate (0, 50, 200, or 400 microg) was topically delivered in the cheek submucosa on the left side (distant to the surgical site) in a small cut into which the gelatin sponge soaked with the drug was placed. RESULTS: Topical application of 200 microg and 400 microg doses of alendronate at the time of surgery was significantly effective (P <0.001) in reducing bone loss. Generally, the percentage of sections with mild bone loss (V1, V2) increased with an increase in the dose of alendronate, while the percentage of sections with severe bone loss (H1, H2) decreased with an increase in alendronate dose. Topical application of 400 microg of alendronate had a systemic effect. CONCLUSIONS: This study implies that topical delivery of alendronate at the time of surgery reduces bone loss in periodontal procedures involving mucoperiosteal flap surgery. The most effective dose is 200 microg for topical delivery at the surgical site and 400 microg for distant sites.


Assuntos
Alendronato/uso terapêutico , Perda do Osso Alveolar/prevenção & controle , Periodonto/cirurgia , Administração Bucal , Administração Oral , Administração Tópica , Alendronato/administração & dosagem , Animais , Distribuição de Qui-Quadrado , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Seguimentos , Esponja de Gelatina Absorvível , Processamento de Imagem Assistida por Computador , Cuidados Intraoperatórios , Mandíbula/cirurgia , Microrradiografia , Análise Multivariada , Ratos , Ratos Wistar , Retalhos Cirúrgicos
12.
J Cell Biochem ; 79(1): 89-102, 2000 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-10906758

RESUMO

Chick limb-bud mesenchymal cells, plated in high-density micro-mass culture, differentiate and form a matrix resembling chick epiphyseal cartilage. In the presence of 4 mM inorganic phosphate or 2.5 mM beta-glycerophosphate mineral deposits upon this matrix forming a mineralized tissue that, based on electron microscopy, x-ray diffraction and Fourier Transform Infrared microspectoscopy, is like that of chick calcified cartilage. In this culture system the initial mineral deposits are found on the periphery of the chondrocyte nodules. During differentiation of the cells in the high-density micro-mass cultures there is a switch from expression of type I collagen to type II, and then to type X collagen. However, type I collagen persists in the matrix. Because there is some debate about whether type I collagen influences cartilage calcification, an immunoblocking technique was used to determine the importance of type I collagen on the mineralization process in this system. Studies using nonspecific goat anti-chick IgG demonstrated that 1-100 ng/ml antibody added with the media after the cartilage nodules had developed (day 7) had no effect on the accumulation of mineral in the cultures. Nonspecific antibody added before day 7 blocked development of the cultures. Parallel solution based cell-free studies showed that IgG did not have a strong affinity for apatite crystals, and had no significant effect on apatite crystal growth. Type I collagen antibodies (1-200 ng/ml) added to cultures one time on day 9 (before mineralization started), or on day 11 (at the start of mineralization), slightly inhibited the accumulation of mineral. There was a statistically significant decrease in mineral accretion with 100 or 200 ng/ml collagen antibody addition continuously after these times. Fab' fragments of nonspecific and type I collagen antibodies had effects parallel to those of the intact antibodies, indicating that the decreased mineralization was not attributable to the presence of the larger, bulkier antibodies. The altered accumulation of mineral was not associated with cell death in the presence of antibody (demonstrated by fluorescent labeling of DNA) or with increased apoptosis (TUNEL-stain). In the immunoblocked cultures, EM analysis demonstrated that mineral continued to deposit on collagen fibrils, but there appeared to be fewer deposits. The data demonstrate that type I collagen is important for the mineralization of these cultures.


Assuntos
Calcificação Fisiológica/fisiologia , Cartilagem/fisiologia , Diferenciação Celular , Colágeno/fisiologia , Animais , Apoptose , Calcificação Fisiológica/imunologia , Cartilagem/citologia , Células Cultivadas , Embrião de Galinha , Galinhas , Imunoglobulina G/imunologia , Imuno-Histoquímica
13.
J Periodontol ; 70(8): 893-5, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10476897

RESUMO

BACKGROUND: Recently, we have shown that local delivery of alendronate reduced significantly bone resorption activated by surgical separation of periosteum from bone. These results advocate the use of local application of alendronate in bone surgeries to prevent regional bone resorption at the surgery site. Here we investigated the efficacy of absorbtion of alendronate by the bone from a gelatin sponge soaked with radiolabeled alendronate applied topically at the surgical site. METHODS: Following elevation of the mucoperiosteal flap next to premolars and molars of the rat mandible, a gelatin sponge soaked with 10 microl of radiolabled alendronate (1 microCi/mg) was applied to exposed bone on one side. The local absorbtion of alendronate and its disposition in the contralateral side of the mandible as well as in the tibia bone were analyzed. RESULTS: The results show that 10% of total alendronate content of the gelatin sponge was absorbed in the bone locally (in the surgical site), while 0.2% was disposed in the tibia. Of interest is the fact that the surgical wound in the contralateral side increased the disposition of alendronate up to 2%. This finding is most likely the result of extravasation and diffusion of alendronate due to surgical wounding. CONCLUSION: This study strongly supports our notion that local delivery of alendronate and its affinity to bone may become a very important treatment modality to prevent resorption of bone during dental and orthopedic procedures.


Assuntos
Alendronato/farmacocinética , Reabsorção Óssea/prevenção & controle , Osteotomia/efeitos adversos , Absorção , Administração Tópica , Alendronato/administração & dosagem , Alendronato/uso terapêutico , Animais , Reabsorção Óssea/etiologia , Mandíbula/metabolismo , Ratos , Ratos Wistar , Tíbia/metabolismo , Distribuição Tecidual
14.
J Periodontol ; 68(9): 884-9, 1997 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9379334

RESUMO

Mucoperiosteal flaps are used to access the bone and root surface in a wide range of periodontal procedures and in implant surgery. We have demonstrated that the mucoperiosteal surgical flap of the rat mandible produces a transient burst of alveolar bone resorption similar to the clinical observations in humans. This resorptive activity, when coupled with local irritation factors, may cause confined alveolar bone loss. Recently, we have demonstrated that an amino bisphosphonate, which is used in preventing systemic bone resorption in osteoporosis and other bone diseases, reduces alveolar bone resorption in the rat model when administered systemically. In this study we evaluated the effect of local delivery of the amino bisphosphonate on bone resorption associated with mucoperiosteal flaps. Following mucoperiosteal flap elevation in the premolar and molar region of the rat mandible, a surgical pellet soaked with amino bisphosphonate was locally applied on the exposed bone surface and covered by flap. The results show that local delivery of amino bisphosphonate reduces significantly alveolar bone resorption activated by mucoperiosteal flap surgery. This study suggests that local application of amino bisphosphonate can be used as an adjunct in therapy for reducing bone resorption following surgery.


Assuntos
Alendronato/uso terapêutico , Processo Alveolar/efeitos dos fármacos , Reabsorção Óssea/prevenção & controle , Doenças Mandibulares/prevenção & controle , Retalhos Cirúrgicos/efeitos adversos , Administração Tópica , Alendronato/administração & dosagem , Perda do Osso Alveolar/diagnóstico por imagem , Perda do Osso Alveolar/etiologia , Perda do Osso Alveolar/patologia , Perda do Osso Alveolar/prevenção & controle , Processo Alveolar/diagnóstico por imagem , Processo Alveolar/patologia , Animais , Doenças Ósseas/prevenção & controle , Reabsorção Óssea/diagnóstico por imagem , Reabsorção Óssea/etiologia , Reabsorção Óssea/patologia , Implantação Dentária/efeitos adversos , Processamento de Imagem Assistida por Computador , Doenças Mandibulares/diagnóstico por imagem , Doenças Mandibulares/etiologia , Doenças Mandibulares/patologia , Microrradiografia , Osteogênese , Osteoporose/prevenção & controle , Doenças Periodontais/cirurgia , Complicações Pós-Operatórias , Ratos , Ratos Wistar , Raiz Dentária/cirurgia
15.
J Cell Biochem ; 64(4): 632-43, 1997 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-9093912

RESUMO

In the presence of 4 mM inorganic phosphate, differentiating chick limb-bud mesenchymal cells plated in micromass cultures form a mineralized matrix resembling that of chick calcified cartilage. To test the hypothesis that cartilage proteoglycans are inhibitors of cell mediated mineralization, the synthesis, content, and turnover of proteoglycans were altered in this system, and the extent of mineralization and properties of the mineral crystals examined. In all cases where the proteoglycan synthesis or proteoglycans present were modified to provide fewer or smaller molecules, mineralization was enhanced. Specifically, when proteoglycan synthesis was blocked by treatment with 10(-10) M retinoic acid, extensive mineral deposition occurred on a matrix devoid of both proteoglycans and cartilage nodules. The crystals, which formed rapidly, were relatively large in size based on analysis by X-ray diffraction or FT-1R microspectroscopy, and were more abundant than in controls. When 2.5 or 5 mM xylosides were used to cause the synthesis of smaller proteoglycans, the extent of mineral accretion was also increased relative to controls; however, the matrix was less affected, and the extent of mineral deposition and the size of the crystals were not as markedly altered as in the case of retinoic acid. Modification of existing proteoglycans by either chondroinase ABC or hyaluronidase treatment similarly resulted in increased mineral accretion (based on 45Ca uptake or total Ca uptake) relative to cultures in which the proteoglycan content was not manipulated. Crystals were more abundant and larger than in control mineralizing cultures. In contrast, when proteoglycan degradation by metalloproteases was inhibited by metal chelation with o-phenanthroline, the Ca accretion at early time points was increased, but as mineralization progressed, Ca accumulation decreased. These data provide evidence that in this culture system, proteoglycans are inhibitors of mineralization.


Assuntos
Calcificação Fisiológica , Mesoderma/metabolismo , Proteoglicanas/metabolismo , Animais , Cartilagem/embriologia , Cartilagem/metabolismo , Diferenciação Celular , Células Cultivadas , Embrião de Galinha , Extremidades/embriologia , Mesoderma/citologia
16.
J Bone Miner Res ; 11(11): 1694-702, 1996 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8915777

RESUMO

Differentiating chick limb-bud mesenchymal cells plated in micromass culture form a cartilage matrix that can be mineralized in the presence of 4 mM inorganic phosphate (Pi), and 1 mM calcium. Previous studies showed that when beta-glycerophosphate (beta GP) is used in place of Pi, the mineral crystals formed are larger and differ in distribution. The present study shows that the difference in distribution is not associated with alterations in cell proliferation, protein synthesis, or with collagen, proteoglycan core protein, or alkaline phosphatase gene expression. Cultures with 2.5, 5, and 10 mM beta GP did show different levels of alkaline phosphatase activity, and in the presence of low (0.3 mM) Ca had different Pi contents (4, 6 and 9 mM, respectively), indicating that the increase in CaxP product may in part be responsible for the altered pattern of mineralization. However, cultures with beta GP in which alkaline phosphatase activity was inhibited with levamisole still had an altered mineral distribution as revealed by Fourier transform-infrared (FT-IR) microspectroscopy. The presence of a casein kinase II-like activity in the mineralizing cultures, the ability of specific inhibitors of this enzyme to block mineralization, and the known ability of beta GP to block phosphoprotein phosphatase activity suggests that altered patterns of matrix protein phosphorylation may influence mineral deposition in these cultures.


Assuntos
Cartilagem Articular/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Glicerofosfatos/farmacologia , Botões de Extremidades/efeitos dos fármacos , Mesoderma/efeitos dos fármacos , Minerais/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Cartilagem Articular/citologia , Cartilagem Articular/metabolismo , Divisão Celular/efeitos dos fármacos , Células Cultivadas , Embrião de Galinha , DNA/metabolismo , Proteínas Fetais/biossíntese , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Hidrólise , Botões de Extremidades/citologia , Botões de Extremidades/metabolismo , Mesoderma/citologia , Mesoderma/metabolismo , Especificidade por Substrato
17.
Calcif Tissue Int ; 58(3): 177-85, 1996 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8852573

RESUMO

It is a common belief that chondrocyte death must precede calcification in the growth plate. To challenge this dogma, cell devitalization was induced in an in vitro model that mimics in situ cartilage calcification. Chick limb-bud mesenchymal cells, plated in micromass culture, differentiate to form a cartilaginous matrix which mineralizes in the presence of inorganic or organic phosphate. The mineral formed resembles physiologic mineral in crystal size, composition, and distribution. Killing cells by water lysis, ethanol fixation, freeze-thawing, trypsinization, or impairing their function by oligomycin treatment prior to the time at which mineralization commenced, prevented mineral deposition. In contrast, devitalizing cells by any of these techniques after mineralization commenced resulted in dystrophic calcification (excessive, randomly distributed mineral of larger than physiologic crystal size). Based on analyses of 45Ca uptake, FT-IR microscopy, X-ray diffraction, and transmission electron microscopy, it is concluded that the presence of viable cells is obligatory for physiologic cartilage calcification in the differentiating chick limb-bud mesenchymal cell culture system.


Assuntos
Calcificação Fisiológica , Cartilagem/metabolismo , Sobrevivência Celular/fisiologia , Animais , Matriz Óssea , Células Cultivadas/ultraestrutura , Embrião de Galinha , DNA/análise , Inibidores Enzimáticos/toxicidade , Mesoderma/citologia , Mesoderma/ultraestrutura , Microscopia Eletrônica , Oligomicinas/toxicidade , Espectroscopia de Infravermelho com Transformada de Fourier
18.
Int J Oral Maxillofac Implants ; 10(6): 729-35, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-8530176

RESUMO

Four biomechanical parameters--peak force, vertical displacement, interface stiffness, and strain energy--were defined to evaluate bone-implant interface properties. These parameters were measured at placement and after 3 months of healing during push-in tests on commercially pure titanium implants placed in the mandibles of dogs in a one-phase nonsubmerged procedure. Comparison of the results showed that peak force, interface stiffness, and strain energy increased after 3 months of healing, but vertical displacement decreased. These findings suggest that the interface stiffness, which is considered a major factor for implant success, increases during 3 months of healing in dogs, which corresponds to a 4- to 6-month healing period in human mandibles.


Assuntos
Implantes Dentários , Análise do Estresse Dentário , Osseointegração , Processo Alveolar/fisiologia , Animais , Implantação Dentária Endóssea , Cães , Mandíbula , Estresse Mecânico , Titânio , Cicatrização
19.
J Periodontol ; 66(11): 999-1003, 1995 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8558403

RESUMO

Following elevation of a full thickness flap a transient burst of regional remodeling occurs. This phenomenon is termed in orthopedic surgery as regional accelerated phenomenon (RAP), beginning with accelerated resorption activity followed by a slow process of bone regeneration. Recently we have demonstrated that a mucoperiosteal surgical flap of rat mandible is producing a typical RAP process. Bisphosphonates are synthetic compounds that are taken up preferentially by the skeleton and suppress osteoclast-mediated bone resorption by a mechanism that is not yet fully understood. Amino bisphosphonate has been shown to inhibit active bone resorption without interfering with bone formation. In this study we evaluated the effect of amino bisphosphonate on bone resorption associated with a mucoperiosteal flap used as a resorptive model. We compared the effect of amino bisphosphonate in rats using IV administration with topical application at 3 dose levels. The results show that topical application of all 3 doses (0.15, 0.75, and 1.5 mg/ml) had no inhibiting effect on bone resorption after surgery, while IV administration at 0.5 mg/kg body weight significantly reduced the bone resorption. Interestingly, in the non-operated side, amino bisphosphonate increased mineral density.


Assuntos
Perda do Osso Alveolar/prevenção & controle , Remodelação Óssea/efeitos dos fármacos , Difosfonatos/uso terapêutico , Retalhos Cirúrgicos/efeitos adversos , Administração Tópica , Animais , Densidade Óssea/efeitos dos fármacos , Difosfonatos/administração & dosagem , Difosfonatos/farmacologia , Injeções Intravenosas , Masculino , Ratos , Ratos Wistar
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