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PubMed2007

Bone regeneration using hyaluronic acid-based hydrogel with bone morphogenic protein-2 and human mesenchymal stem cells.

Acrylated hyaluronic acid (HA) was used as a scaffold for bone morphogenic protein-2 (BMP-2) and human mesenchymal stem cells (hMSCs) for rat calvarial defect regeneration. HA was acrylated by two-step reactions: (1) introduction of an amine group using adipic acid dihydrazide (ADH); (2) acrylation by N-acryloxysuccinimide. Tetrathiolated poly(ethylene) glycol (PEG-SH(4)) was used as a cross-linker by a Michael-type addition reaction and the hydrogel was formed within 10min under physiological conditions. This hydrogel is degraded completely by 100U/ml hyaluronidase in vitro. hMSCs and/or BMP-2 was added during gelation. Cellular viability in vitro was increased up to 55% in the hydrogels with BMP-2 compared with the control. For in vivo calvarial defect regeneration, five different samples (i.e., control, hydrogel, hydrogel with BMP-2, hydrogel with MSCs, and hydrogel with BMP-2 and MSCs) were implanted for 4 weeks. The histological results demonstrated that the hydrogels with BMP-2 and MSCs had the highest expression of osteocalcin and mature bone formation with vascular markers, such as CD31 and vascular endothelial growth factors, compared with the other samples. This study demonstrated that HA base hydrogel can be used for cell and growth factor carriers for tissue regeneration.

Animals↗
PubMed2003

The effects of enamel matrix derivative (EMD) on osteoblastic cells in culture and bone regeneration in a rat skull defect.

OBJECTIVE: Enamel matrix derivative (EMD) has been clinically used to promote periodontal tissue regeneration. The purpose of the present study is to clarify EMD affects on osteoblastic cells and bone regeneration. MATERIALS AND METHODS: Mouse osteoblastic cells (ST2 cells and KUSA/A1 cells) are used in culture experiments. After cells were treated with EMD, cell growth was evaluated with DNA measurement, 5-bromo-2'-deoxyurydine (BrdU) incorporation assay. Measurement of alkaline phosphatase (ALP) activity and mineralized-nodule (MN) formation, Northern blotting analysis and zymography are also performed. In addition, EMD was applied to a rat skull defect and the defect was radiographically and histologically evaluated 2 weeks after the application. RESULTS: EMD did not stimulate ST2 cell growth; however, it enhanced KUSA/A1 cell proliferation. Although EMD stimulated ALP activity in both the cells, ALP activity in KUSA/A1 cells was affected to a much greater degree. Corresponding to the increase in ALP activity, MN formation in KUSA/A1 cells was enhanced by EMD. EMD stimulated osteoblastic phenotype expression of KUSA/A1 cells such as type I collagen, osteopontin, transforming growth factor beta 1 and osteocalcin. EMD treatment also stimulated matrix metalloproteinase production in KUSA/A1 cells. Although the effects of EMD on osteoblastic cells depend on cell type, the overall effect of EMD on osteoblastic cells is stimulatory rather than inhibitory. Finally, EMD application to a rat skull defect accelerated new bone formation. CONCLUSION: These results indicate that EMD affects osteoblastic cells and has potential as a therapeutic material for bone healing.

Alkaline Phosphatase↗
PubMed1996

Healing of osseous submucous cleft palates with guided bone regeneration.

The aim of this study was to develop an experimental model in rats of an osseous submucous cleft palate and to examine if bone regeneration can be achieved in such defects by the placement of membranes according to the principle of guided tissue regeneration (GTR). An osseous submucous cleft palate defect (5 mm x 2 mm) was created surgically in Wistar rats. Membranes of expanded polytetrafluoroethylene were placed so that they covered both the nasal and the palatal aspect of the defect before the palatal mucoperiosteal flap was repositioned and sutured. Histological analysis after seven weeks of healing showed that significantly more test animals (5/9) healed with newly formed bone and a suture-like tissue in the middle of the defects than controls treated without membranes (0/17). In specimens evaluated macroscopically after 12 weeks, the corresponding rates for the test group were 12/12 compared with 0/13. These observations indicate that an experimental model of an osseous submucous cleft palate can be established in rats, and that complete osseous healing and creation of a midpalatal suture-like tissue in the bony defect is favoured by the placement of membranes according to the principle of GTR.

Animals↗
PubMed1984

Pre-B cells in bone marrow: size distribution profile, proliferative capacity and peanut agglutinin binding of cytoplasmic mu chain-bearing cell populations in normal and regenerating bone marrow.

Pre-B cell populations in mouse bone marrow, identified by double immunofluorescence labelling of cytoplasmic and surface mu chains (c mu, s mu), have been characterized by cell size, proliferative capacity and the binding of peanut agglutinin (PNA). In the normal steady state of lymphocyte production the size distribution profile of cytocentrifuged c mu + s mu- cells was bimodal. A population of large cells in rapid cell cycle was revealed by arresting cells in mitosis with vincristine. Many c mu + s mu- cells, however, formed a nondividing population of small lymphocytes, resembling s mu + cells in size distribution. During regeneration from sublethal whole body X-irradiation (150 rads) a marked enrichment of large c mu + s mu- cells preceded small c mu + s mu- and s mu + cells; progressive changes in cell size distribution reflected a wave of B lymphocyte genesis. The c mu + s mu- cells in foetal liver resembled those in regenerating marrow. Surface binding of PNA characterised all c mu + s mu- cell populations in normal and regenerating bone marrow and in foetal liver, whereas only a minority of s mu + cells and mu-negative marrow cells bound PNA strongly. The present size distribution analyses allow a correlation with other cytological and functional studies of marrow lymphocyte precursors in defining the place of pre-B cells in B lymphocyte genesis.

Animals↗
PubMed2005

[Methods for the evaluation of bone regeneration during distraction osteogenesis].

During limb lengthening gradual reconstruction of bone tissue in distraction gap requires constant, systematic control and evaluation. This process is depicted descriptively and subjectively. Changes happening during osteogenesis are dynamic, they can stop, slow down or accelerate, and regenerate may be of various shape and form. In this work different methods of bone regenerate evaluation are presented. They may be divided on two basic groups. First group contains methods with X-radiation, and the second - without X-rays. Examinations that evaluate arising bone regenerate may be also divided on descriptive examinations and quantitative. Despite that different methods are used for distraction osteogenesis course estimation, classic radiological examination remains the basic one. The rest of them are most often supplementary examinations, useful in selected stages of treatment, for e.g. ultrasonography in first stage of regenerate arising. So it seems, that future is in quantitative regenerate evaluation using radiographs. Classic X-ray picture made in reproducible and repeatable conditions may be subjected to digital, quantitative image analysis, and acquired results enables for more precise and more balanced evaluation of new bone formation in distraction osteogenesis.

Bone Regeneration↗
PubMed2002

Effects of simvastatin on bone regeneration in the mandibles of ovariectomized rats and on blood cholesterol levels.

The purpose of this study was to evaluate the effects of simvastatin on guided bone regeneration in the mandibles of ovariectomized rats, and to observe their blood cholesterol levels. Seventy female rats were divided into two groups: control and treated, both groups containing normal and ovariectomized rats. A month after ovariectomy a bone defect was created in the mandible, and was covered by a polytetrafluoroethylene membrane. The treated groups received simvastatin orally for 15 or 30 days. The rats were sacrificed 15, 30 or 60 days after surgery, at which time a blood sample was extracted for blood cholesterol level analysis and the mandible was extracted for densitometric, histological and morphometric analysis. All specimens underwent analysis of variance. The ovariectomized animals had higher cholesterol levels than the treated normal animals, and no significant difference was found between the different treatment periods and the sacrifice times. The densitometric, histological and morphometric analysis showed that the treated ovariectomized animals developed more new bone than the control ovariectomized rats, but no significant difference was observed between the treatment periods. It can be concluded that the deficiency of estrogen increased the level of blood cholesterol and that the simvastatin aided new bone formation in the ovariectomized animals.

Absorptiometry, Photon↗
PubMed2006

Evaluation of bone regeneration by DNA release from composites of oligo(poly(ethylene glycol) fumarate) and cationized gelatin microspheres in a critical-sized calvarial defect.

This research examines the bone formation response to release of plasmid DNA encoding human Bone Morphogenetic Protein-2 from hydrogel composites consisting of cationized gelatin microspheres (CGMS) embedded within a crosslinked oligo(poly(ethylene glycol) fumarate) (OPF) hydrogel network in a critical-sized rat cranial defect model after 30 days. Four composite groups were investigated: (1) composites with 10 microg DNA loaded into the CGMS phase, (2) composites with 10 microg DNA loaded into the OPF phase, (3) composites with 100 microg DNA loaded into the OPF phase, and (4) composites without DNA (material control). Light microscopy revealed no enhancement in bone formation for groups releasing plasmid DNA, relative to the material control group. Limited formation of new bone was observed from the defect margins and within the defect for some samples. The hydrogels swelled appreciably and fragmentation of the implants was noted to varying degrees among samples within groups, with a presence of inflammatory cells related to the degree of fragmentation. The lack of enhancement in bone formation indicates that the release of plasmid DNA from the composites was not sufficient to elicit a bone regeneration response.

Animals↗
PubMedDate not supplied

Alveolar bone regeneration pattern following surgical and non-surgical treatment in juvenile periodontitis.

One hundred and fifty six interproximal sites, with periodontal pockets deeper than 5mm and showing loss of bone on standard dental periapical radiographs, were treated by subgingival instrumentation and open periodontal flap debridement in 12 patients properly motivated and given thorough oral hygiene instructions. The indices of gingival condition, plaque, calculus, oral hygiene and degree of mobility with loss of attachment were measured at baseline, 1,3 and 6 months after treatment. Standardized reproducible radiographs of the interproximal sites were taken before and 6 months after treatment. Alveolar bone levels pre and post treatment were measured with a grid in square millimetres using a view box (Watson and sons, London) and the Dunning and Leach gingival bone count index for both treatment procedures. Radiographic analysis showed statistically and clinically significant increases in bone fill of both the superficial and deep bone defects for the surgical technique (p < 0.05). This study has shown that surgical procedure resulted in a better bone regeneration than subgingival instrumentation.

Adolescent↗
PubMed2003

Bone regeneration after surgical repositioning of impacted mandibular second molars: a case report.

A case is presented where the mesially impacted mandibular second molar teeth were surgically uprighted in an 11-year-old female patient. Bone regeneration is shown in the areas occupied by the impacted second molars with maturation of bone and cortication of the crest of the alveolar bone. The probing depths are also normal with no residual bony defects. This healing was achieved with no bone grafting procedure, emphasizing two important factors: to prevent/minimize any trauma to the tissues at the site of elevation and uprighting of the tooth (i.e. maintaining viable periodontal ligament cells and minimal cementum damage); and to obtain primary closure whilst allowing the tissue in the mesial defect to reorganize against the scaffold of bone. However, the procedure on the one side was complicated with necrosis and infection of the pulp space with external inflammatory root resorption. Endodontic therapy of this tooth proved to be successful with periradicular healing radiographically and re-establishment of the lamina dura. At the 3-year follow-up, the endodontically treated tooth showed no clinical and radiographic signs of pathology. The left second mandibular molar had no pulpal or periodontal postsurgical complications, which may be attributed to apparently more open apices allowing for pulp revascularization after manipulation at the time of surgery. This report illustrates unassisted wound healing that occurs in the area of uprighting with complete reconstitution of periodontal anatomy without additional regenerative procedures to augment bone.

Bicuspid↗
PubMed1996

Qualitative and quantitative analysis of orthotopic bone regeneration by marrow.

A rat model of a femoral segmental defect was used to specifically test the hypothesis that autogenous marrow has the osteogenic capability to heal a bone defect. The variables analyzed included the ratio of the marrow volume to the defect, implantation of live or dead marrow, and remodeling of established nonunions by implantation of live marrow. The uniqueness of this model allows biomechanical evaluation of the new bone formed by the implant. When live marrow was implanted, woven bone formed at 3 weeks, progressing to early lamellar bone at 6 weeks, with subsequent remodeling for as long as 12 weeks in a volumetric fashion (p < 0.05). Bone marrow, when placed in a fresh femoral defect and given in sufficient amounts, produced a rate of union comparable with that of autologous bone grafts. Mature lamellar bone formed by marrow was evaluated biomechanically; the results were statistically comparable with those of cancellous bone grafts at 12 weeks. Significant bone formation occurred when marrow was percutaneously injected in femoral nonunions, although union and remodeling did not take place in this rat model. Implantation of dead marrow resulted in rare cellular infiltration and minimal bone formation in a manner comparable with that of autogenous cancellous bone grafts. These results indicate that bone marrow can lead to structurally functional bone regeneration in an orthotopic location.

Analysis of Variance↗
PubMed2004

Development of guided bone regeneration membrane composed of beta-tricalcium phosphate and poly (L-lactide-co-glycolide-co-epsilon-caprolactone) composites.

To create biodegradable and thermoplastic materials for guided bone regeneration, GBR, and guided tissue regeneration, GTR, membranes, composites of beta-tricalcium phosphate, TCP, and biodegradable polyesters, poly (L-lactide-co-glycolide-co-epsilon-caprolactone), PLGC, and poly (L-lactide-co-epsilon-caprolactone), PLCL, were prepared by a heat-kneading method. The composites maintained thermoplasticity and mechanical strength by formation of a chemical interaction between Ca on TCP and C=O on the lactide segment of PLGC or PLCL. The composites also indicated composite effects in pH auto-regulation property and elongation of biodegradation period, e.g., the composites maintained their mechanical strength up to 12 weeks after soaking in both physiological and phosphate-buffered saline, and the period was sufficient time to use for GBR and GTR membranes. Animal tests for GBR indicated that the present composite membrane successfully regenerated beagles' mandible defects 10 x 10 x 10 mm3 in size. These results suggested that the TCP/PLGC bioresorbable composites could be utilized for GBR and GTR therapy.

Animals↗
PubMed1980

[Participation of bone marrow stromal precursor cells and bone regeneration during transosseous osteosynthesis].

Changes in the proliferative activity and in the number of bone marrow stromal precursor cells (SPC) in the dog long bone fixed with Ilizarov's apparatus were studied by cloning in monolayer cultures over a period of leg lengthening. It was demonstrated that in 1-1 1/2-year-old dogs the number of dividing SPC in the tibia increased up to 95% by termination of the distraction (60 days). Concurrently, the colony-forming efficiency (CFE) increased 11-fold. In the contralateral tibia (CFE significantly rose during the distraction, while in the humeri it decreased 2.5-fold as compared to control. A conclusion is drawn about participation of SPC in bone regeneration.

Animals↗
PubMed2001

Guided bone regeneration for dehiscence and fenestration defects on implants using an absorbable polymer barrier.

BACKGROUND: Guided bone regeneration (GBR) using a non-absorbable barrier has provided clinicians the ability to place implants in sites compromised by insufficient bone, including immediate extraction sites. Recent evidence suggests that successful GBR outcomes may be possible using bioabsorbable polymer barriers. METHODS: This report presents a case series of 9 patients with 8 fenestration and 3 dehiscence defects on implants consecutively treated with GBR. A bioabsorbable polymer barrier of poly(DL-lactide) was used in conjunction with a composite graft of freeze-dried bone allograft (FDBA)/demineralized freeze-dried bone allograft (DFDBA) mixed in a ratio of 1:1. Second-stage surgeries were performed at 4 to 8.5 months (5. 7 months average) post-placement. Biopsy material from 2 sites was obtained while exposing the implant for healing abutment connection. RESULTS: Ten of the 11 defects (90.9%) achieved complete coverage of the osseous defects. Histologic evaluations revealed the formation of viable bone, frequently in close amalgamation with residual graft particles. CONCLUSION: These case reports suggest that a poly(DL-lactide) polymer can be used as a physical barrier with a composite bone replacement graft to achieve successful GBR results of dehiscence/fenestration defects when placing implants.

Absorbable Implants↗
PubMed1981

Comparison of cell proliferation in the regenerating bone marrow and spleen of irradiated mice with the use of 125I-iododeoxyuridine.

The method of 125IUdR labelling of hemopoietic cell populations was used to estimate differences of repopulation kinetics in the femoral bone marrow and spleen of sublethally irradiated mice. In regenerating bone marrow the cellularity and proliferation index, as measured by 6 h 125IUdR incorporation, were found to be inversely related. In the spleen the proliferation index increased parallelly with the increase in cellularity and indicates an ineffectiveness of a change in the set point of local cellularity control. Experiments with measuring the retention of 125IUdR in hemopoietic organs revealed, in the spleen of irradiated animals, phases of increased cell losses as well as immigration of labelled cells into this organ.

Animals↗
PubMed2006

Lethal photosensitization and guided bone regeneration in treatment of peri-implantitis: an experimental study in dogs.

The purpose of this study was to evaluate the effect of lethal photosensitization and guided bone regeneration (GBR) on the treatment of ligature-induced peri-implantitis in different implant surfaces. The treatment outcome was evaluated by clinical and histometric methods. A total of 40 dental implants with four different surface coatings (10 commercially pure titanium surface (cpTi); 10 titanium plasma-sprayed (TPS); 10 acid-etched surface; 10 surface-oxide sandblasted) were inserted into five mongrel dogs. After 3 months, the animals with ligature-induced peri-implantitis were subjected to surgical treatment using a split-mouth design. The controls were treated by debridment and GBR, while the test side received an additional therapy with photosensitization, using a GaAlAs diode laser, with a wavelength of 830 nm and a power output of 50 mW for 80 s (4 J/cm2), and sensitized toluidine blue O (100 microg/ml). The animals were sacrificed 5 months after therapy. The control sites presented an earlier exposition of the membranes on all coating surfaces, while the test group presented a higher bone height gain. Re-osseointegration ranged between 41.9% for the cpTi surface and 31.19% for the TPS surface in the test sites; however differences were not achieved between the surfaces. The lethal photosensitization associated with GBR allowed for better re-osseointegration at the area adjacent to the peri-implant defect regardless of the implant surface.

Acid Etching, Dental↗