Morphometric evaluation of the repair of critical-size defects using demineralized bovine bone and autogenous bone grafts in rat calvaria

Objective: To evaluate the repair of critical-size bone defects in rats treated with demineralized bovine bone (DBB) compared with autogenous bone (AB). Material and method: A bone defect of 8 mm in diameter was created in the calvaria of 50 Rattus norvegicus, treated either with DBB or AB. Sub-groups of five rats of each group were killed at 7, 14, 21, 30 and 90 days post-operatively, and the skulls were removed and processed histologically. Histological sections were stained with hematoxylin and eosin. Result: Histological analysis showed complete closure of the defects with new bone at 90 days in group AB, and substitution of the biomaterial by fibrotic connective tissue in the DBB group at 21 days. Morphometric analysis showed that DBB was rapidly absorbed at 14 days, with its volume density decreasing from 47%+/- 0.8% at 7 days to 1.2%+/- 0.41% at 14 days. Subsequently, volume densities of the connective tissue and neoformed bone increased from 51.1%+/- 11.17% to 86.8%+/- 7.92% and from 1.9%+/- 1.13% to 12%+/- 8.02%, respectively, for the same time interval. The volume density of AB particles did not change throughout the experimental periods, but the amount of new bone increased markedly between 7 and 90 days, from 4.5%+/- 1.57% to 53.5%+/- 6.42% (P < 0.05). Conclusion: DBB did not provide complete repair of the defects, with significantly less new bone formation than in the AB group.

Comparative histomorphometric and tomographic analysis of maxillary sinus floor augmentation in rabbits using autografts and xenografts

Our goal was to evaluate bone neoformation promoted by a bovine xenograft composite (XC) compared with autogenous graft for maxillary sinus augmentation in a rabbit model. The left maxillary sinus of 18 male rabbits was filled with 200 mg of cortical and cancellous autogenous bone and the right sinus was filled with 200 mg of a composite comprised organic and inorganic bovine matrices, pool of bBMPs and collagen. Postoperative implant intervals of 2, 4, and 8 weeks were analyzed. Differences in the bone optical density among the groups and experimental periods were evaluated by computed tomography analysis. The tissue response was evaluated by histomorphometric analysis of the newly formed bone, connective tissue and/or granulation tissue, residual material, and bone marrow. The tomographic analyses showed a maximum optical density in the 4-week period for both groups. Histologically, an inflammatory infiltrate was observed at 2 weeks in the XC group but exclusively around the organic particles of the biomaterial. Regarding to the amount of newly formed bone, no statistical differences (p > 0.05) were observed among the two treatments throughout the implant intervals. However, by the end of the 8 weeks, the quantity of bone marrow was two times greater (p < 0.05) in the control group than in the XC group. In conclusion, the xenograft composite promotes formation of new bone in a similar fashion to autogenous bone and could therefore be considered a biomaterial with potential applications as a bone substitute in maxillary sinus floor augmentation. (C) 2007 Wiley Periodicals, Inc.

Response of human alveolar bone-derived cells to a novel poly(vinylidene fluoride-trifluoroethylene)/barium titanate membrane

This study investigated the response of human alveolar bone-derived cells to a novel poly(vinylidene fluoride-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT) membrane. Osteoblastic cells were cultured in osteogenic conditions either on P(VDF-TrFE)/BT or polytetrafluoroethylene (PTFE) for up to 14 days. At 7 and 14 days, the mRNA expression of Runt-related transcription factor 2 (RUNX2), Type I collagen (COL I), Osteopontin (OPN), Alkaline phosphatase (ALP), Bone sialoprotein (BSP), and Osteocalcin (OC), key markers of the osteoblastic phenotype, and of Bcl2-associated X protein (Bax), B-cell CLL/lymphoma 2 (Bcl-2), and Survivin (SUR), associated with the control of the apoptotic cell death, was assayed by real-time PCR. In situ ALP activity was qualitatively evaluated by means of Fast red staining. Surface characterization was also qualitatively and quantitatively assayed in terms of topography, roughness, and wettability. Cells grown on P(VDF-TrFE)/BT exhibited a significantly higher mRNA expression for all markers compared to the ones on PTFE, except for Bcl-2, which was not detected for both groups. Additionally, Fast red staining was noticeably stronger in cultures on P(VDF-TrFE)/BT at 7 and 14 days. At micron-and submicron scale, SEM images and roughness analysis revealed that PTFE and P(VDF-TrFE)/BT exhibited a smooth topography and a similar roughness, respectively. PTFE membrane displayed higher contact angles compared with P(VDF-TrFE)/BT, as indicated by wettability assay. The novel P(VDF-TrFE)/BT membrane supports the acquisition of the osteoblastic phenotype in vitro, while up-regulating the expression of apoptotic markers. Further in vivo experiments should be carried out to confirm the capacity of P(VDF-TrFE)/BT membrane in promoting bone formation in guided bone regeneration.

Imbalance between matrix metalloproteinases and tissue inhibitor of metalloproteinases in hypertensive vascular remodeling

Structural vascular changes in two-kidney, one-clip (2K-1C) hypertension may result from increased matrix metalloproteinase (MMP)-2 activity. MMP-2 activation is regulated by other MMPs, including transmembrane-MMPs, and by tissue inhibitors of MMPs (TIMPs). We have investigated the localization of MMP-2, -9, -14, and TIMPs 1-4 in hypertensive aortas and measured their levels by zymography/Western blotting and immunohistochemistry. Gelatinolytic activity was assayed in tissues by in situ zymography. Sham-operated and 2K-1C hypertensive rats were treated with doxycycline (or vehicle) for 8 weeks, and the systolic blood pressure was monitored weekly. Doxycycline attenuated 2K-1C hypertension (165 +/- 11.7 mmHg versus 213 +/- 7.9 mm Hg in hypertensive controls, P<0.01), and completely prevented increase in the thicknesses of the media and the intima in 2K-1C animals (P<0.01). Increased amounts of MMP-2, -9, and -14 were found in hypertensive aortas, as well as enhanced gelatinolytic activity. A gradient in the localization of MMP-2, -9, and -14 was found, with increased amounts detected in the intima, at sites with higher gelatinolytic activity. Doxycycline attenuated hypertension induced increases in all the 3 investigated MMPs in both the media and the intima (all P<0.05). but it did not change the amounts of TIMPs 1-4 (P>0.05). Therefore, an imbalance between increased amounts of MMPs at the tissue level without a corresponding increase in the quantities of TIMPs, particularly in the intima and inner media layers, appears to account for the increased proteolytic activity found in 2K-1C hypertension-induced maladaptive vascular remodeling. (C) 2009 Elsevier B.V. All rights reserved.

In vitro biocompatibility of poly(vinylidene fluoride-trifluoroethylene)/barium titanate composite using cultures of human periodontal ligament fibroblasts and keratinocytes

The mm of this work was to evaluate the biocompatibility of poly(vinylidene fluoride-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT) membrane to be used in guided tissue regeneration (GTR) Fibroblasts from human periodontal ligament (hPDLF) and keratinocytes (SCC9) were plated on P(VDF-TrFE)/BT and polytetrafluorethylene membranes at a cell density of 20.000 cells well(-1) and Cultured for up to 21 days Cell morphology, adhesion and proliferation were evaluated in hPDLF and keratinocytes, while total protein content and alkaline phosphatase (ALP) activity were assayed only for hPDLF Using a higher cell density. real-time polymerase chain reaction (PCR) was performed to assess the expression of typical genes of hPDLF, such as periostin, PDLs17, S100A4 and fibromodulin, and key phenotypic markers of keratinocytes, including involucrin, keratins 1. 10 and 14 Expression of the apoptotic genes bax, bcl-2 and Survivin was evaluated for both cultures hPDLF adhered and spread more oil P(VDF-TrFE)/BT, whereas keratinocytes showed a round shape on both membranes. hPDLF adhesion was greater oil P(VDF-TrFE)/BT at 2 and 4 h, while keratinocyte adhesion was similar for both membranes. Whereas proliferation was significantly higher for hPDLF on P(VDF-TrFE)/BT at days 1 and 7. no signs of keratinocyte proliferation could be noticed for both membranes Total protein content was greater on P(VDF-TrFE)/BT at 7, 14 and 21 days, and higher levels of ALP activity were observed oil P(VDF-TrFE)/BT at 21 days. Real-time PCR revealed higher expression of phenotypic markers of hPDLF and keratinocytes as well as greater expression of apoptotic genes in cultures grown on P(VDF-TrFE)/BT. These results indicate that, by favoring hPDLF adhesion. spreading. proliferation and typical mRNA expression, P(VDF-TrFE)/BT membrane should be considered an advantageous alternative for GTR (C) 2009 Acta Materialia Inc Published by Elsevier Ltd All rights reserved

Assessment of matrix metalloproteinase (MMP)-2, MMP-8, MMP-9, and their inhibitors, the tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 in obese children and adolescents

Objectives: To compare the circulating levels of matrix metalloproteinase (MMP)-8, pro-MMP-2, pro-MMP-9, and total MMP-9, their endogenous inhibitors, the tissue inhibitors of metalloproteinases (TIMP)-1 and TIMP-2, and the MMP-8/TIMP-1, MMP-9/TIMP-1, and MMP-2/TIMP-2 ratios in normotensive obese children and adolescents with those found in non obese children and adolescents. Design and methods: We studied 40 obese and 40 non obese (controls) children and adolescents in this cross-sectional study. MMP and TIMP concentrations were measured in plasma samples by gelatin zymography and ELISA. Results: Obese children and adolescents had higher circulating MMP-8 concentrations, lower plasma TIMP-1 concentrations, and higher MMP-8/TIMP-1 ratios than non obese controls (P < 0.05). We found no differences in pro-MMP-9 or total MMP-9 levels, or in MMP-9/TIMP-1 ratios between groups (P > 0.05). While we found no significant differences in pro-MMP-2 levels (P > 0.05) obese Subjects had higher TIMP-2 concentrations and lower pro-MMP-2/TIMP-2 ratios (P < 0.05) than non obese controls. Conclusions: In conclusion, we found evidence indicating higher net MMP-8 (but not MMP-9 and MMP-2) activity in childhood obesity. The increased MMP-8 levels found in obese children suggest a possibly relevant pathophysiological mechanism that may be involved in the increase of cardiovascular risk associated with childhood obesity. (c) 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Human osteoblastic cell response to a Ca- and P-enriched titanium surface obtained by anodization

The aim of the present study was to evaluate the in vitro osteogenic potential of subcultured human osteoblastic cells derived from alveolar bone on a titanium (Ti) surface produced by an anodized alkali treatment (BSP-AK). Primary osteoblastic cells were subcultured on BSP-AK and machined Ti discs (control) and grown for periods of up to 21 days under osteogenic conditions. Morphologic and biochemical methods were used to assess important parameters of in vitro bone-like tissue formation. Although no major differences were observed between the BSP-AK and the control Ti surface in terms of cell attachment and mineralized matrix formation, a significant increase in cell population, ALP activity, and collagen content was detected in cultures on BSP-AK surface. Our results demonstrate that human osteoblastic cells are sensitive to the BSP-AK-modified Ti surface during the transitional stage between the end of the proliferative phase and the onset of the differentiation /matrix maturation ones. Together with the good mechanical properties exhibited by the Ca- and P- coating, our findings suggest that BSP-AK treatment could be useful for the development of a new surface for dental and orthopedic implants. (c) 2008 Wiley Periodicals, Inc.J Biomed Mater Res 88A: 841-848, 2009

Influence of decortication of the recipient graft bed on graft integration and tissue neoformation in the graft-recipient bed interface

The objective of the present study was to assess the influence of decortication of the posterior elements of the vertebra (recipient bed) and the nature of the bone graft (cortical or cancellous bone) on graft integration and bone, cartilage and fiber neoformation in the interface between the vertebral recipient bed and the bone graft. Seventy-two male Wistar rats were divided into four experimental groups according to the presence or absence of decortication of the posterior vertebral elements and the use of a cortical or cancellous bone graft. Group I-the posterior elements were decorticated and cancellous bone used. Group II-the posterior elements were decorticated and cortical graft was used. Group III-the posterior elements were not decorticated and cancellous graft was used. Group IV-the posterior elements were not decorticated and cortical graft was used. The animals were killed 3, 6 and 9 weeks after surgery and the interface between the posterior elements and the bone graft was subjected to histomorphometric evaluation. Mean percent neoformed bone was 40.8% in group I (decortication and cancellous graft), 39.13% in group II (decortication and cortical graft), 6.13% in group III (non-decorticated and cancellous graft), and 9.27% in group IV (non-decorticated and cortical graft) for animals killed at 3 weeks (P = 0.0005). For animals killed at 6 weeks, the mean percent was 38.53% for group I, 40.40% for group II, 10.27% for group III, and 7.6% for group IV (P = 0.0005), and for animals killed at 9 weeks, the mean was 25.93% for group I, 30.6% for group II, 16.4% for group III, and 18.73% for group IV (P = 0.0026). The mean percent neoformed cartilage tissue was 8.36% for group I, 7.46% for group II, 11.1% for group III, and 9.13% for group IV for the animals killed at 3 weeks (P = 0.6544); 6.6% for group I, 8.07% for group, 7.47% for group III and 6.13% for group IV (P = 0.4889) for animals killed at 6 weeks, and 3.13% for group I, 4.06% for group II, 10.53% for group III and 12.07% for group IV (P = 0.0006) for animals killed at 9 weeks. Mean percent neoformed fibrous tissue was 11% for group I, 6.13% for group II, 26.27% for group III and 21.87% for group IV for animals killed at 3 weeks (P = 0.0008); 7.67% for group I, 7.1% for group II, 9.8% for group III and 10.4% for group IV (P = 0.7880) for animals killed at 6 weeks, and 3.73% for group I, 4.4% for group II, 6.67% for group III and 6.8% for group IV (P = 0.0214) for animals killed at 9 weeks. The statistically significant differences in percent tissue formation were related to decortication of the posterior elements. The use of a cortical or cancellous graft did not influence tissue neoformation. Ossification in the interface of the recipient graft bed was of the intramembranous type in the decorticated animals and endochondral type in the non-decorticated animals.

The relationship between interimplant distances and vascularization of the interimplant bone

Background Long-term success of the implant restorations is based upon the biology and vasculature of the bone surrounding the implants, especially for the bone between two implants. Purpose The aim of this study was to evaluate how loaded implants placed 2 or 3 mm apart influence bone vessel organization. Material and methods Six mongrel dogs were used for the study. The four mandibular premolars were extracted and 3 months later, four 4.5 x 10 mm implants were placed on each side of the mandible. The implants were placed so that two adjacent implants were 2 mm (group 1) or 3 mm (group 2) distant from each other. After 12 weeks, the implants were loaded with provisional prostheses, then metallic crowns were placed 4 weeks later. Both temporary and metallic restorations were made so that the distance between the contact point and the bone crest was 5 mm. The animals were sacrificed after 8 weeks. The hemi-mandibles were removed and prepared for analysis. The interimplant bone vasculature of the two groups was studied using scanning electron microscopic images fractal analysis. The fractal dimension (D(f)) was calculated using the box-counting method. Results The values of the D(f) for the blood vessels were significantly higher (P <.05) in the specimens of the group 2 (1.969 +/- 0.169) than the group 1 (1.556 +/- 0.246). Conclusion The presence of more blood vessels in the group 2 is another indication that 3 mm is a preferable distance for contiguous implants than the 2 mm distance. To cite this article:Traini T, Novaes AB, Piattelli A, Papalexiou V, Muglia VA. The relationship between interimplant distances and vascularization of the interimplant bone.Clin. Oral Impl. Res. 21, 2010; 822-829.doi: 10.1111/j.1600-0501.2010.01926.x.