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This study compared the dimensional alterations, the need for sinus floor elevation, and the histologic wound healing of augmented and nonaugmented alveolar sockets. Sixteen human extraction sockets were either grafted or left untreated. At baseline and 3 and 6 months postextraction, alveolar ridge alterations were evaluated; at 3, 6, and 9 months, histologic analyses were conducted. Implant placement with or without sinus floor augmentation was decided at 6 months. Three of eight patients in the control group underwent sinus floor augmentation compared to one of six in the experimental group. The alveolar ridge augmentation procedure presented here increases the possibility of inserting implants without the need for a sinus augmentation procedure. (Int J Periodontics Restorative Dent 2010;30:265-273.). [ABSTRACT FROM AUTHOR]

This preclinical study evaluated the efficacy of purified recombinant human platelet-derived growth factor (rhPDGF-BB), combined with a novel equine hydroxyapatite and collagen (eHAC) bone block, in providing vertical bone regeneration in critical-size defects simulating localized mandibular alveolar bone atrophy. In addition, the impact of barrier membrane placement in growth factor-mediated bone regeneration was also studied. Bilateral posterior mandibular defects simulating severe localized bony atrophy were created in 12 adult foxhounds following removal of all four mandibular premolars. Three months later, the defects were grafted as follows: group A: eHAC block alone; group B: eHAC block + collagen membrane; group C: eHAC block + rhPDGF-BB; group D: eHAC block + rhPDGF-BB + membrane. The animals were sacrificed after 5 months and the grafted areas were examined histologically, radiographically, and clinically. Groups A and B (controls) exhibited little to no vertical bone regeneration. Group C demonstrated significant vertical bone regeneration, with dense, well-vascularized bone, high bone-to-implant contact, and accelerated replacement of graft particles with newly formed bone. In group D, with the imposition of a barrier membrane, robust bone regeneration was less evident when compared to group C. As in the first study in this series, the importance of the periosteum as a source of osteoprogenitor cells in growth factor-mediated regenerative procedures is examined. [ABSTRACT FROM AUTHOR]

Purpose: To compare clinically and histologically an allogeneic bone matrix to autogenous bone chips in the vertical ridge augmentation technique using titanium-reinforced e-PTFE membranes. Materials and Methods: The study protocol was designed to include patients with bilateral posterior mandibular partial edentulism. Patients were treated with a split-mouth design approach: each side was randomly assigned to the test group (titanium-reinforced e-PTFE membrane and allogeneic bone matrix) or to the control group (titanium-reinforced e-PTFE membrane and autogenous bone chips). Different clinical parameters including the amount of vertically regenerated bone (DSB) and biologic complications were recorded. Histomorphometric analysis and the bone-implant contact percentage were performed. Results: Five female patients were enrolled in the study. Ten edentulous sites were vertically augmented and 25 implants were inserted (13 test group, 12 control group) with a staged approach. In the test group no membrane was exposed. The mean bone regeneration was 4.70 mm (SO 0.48 mm). All 13 implants appeared clinically stable. In the control group, 1 membrane was exposed after 2 months. The mean crestal bone regeneration was 4.10 mm (SO 0.88 mm). All 12 implants were stable at the abutment connection. Nine biopsy specimens from the regenerated areas were evaluated. Vertical bone regeneration was evident in both groups since all the samples demonstrated trabecular bone with different degrees of maturation and mineralization in the regenerated area. Conclusion: Within the limits of this study based on 5 patients, it appears that the behavior of the allogeneic bone matrix is similar to that of autogenous bone chips when used for vertical ridge augmentation by means of gUided bone regeneration techniques. Both grafts demonstrated analogous histologic characteristics. Nevertheless, long-term clinical studies are needed to confirm these preliminary results. [ABSTRACT FROM AUTHOR]

The present investigation was performed to compare the biocompatibility, safety, and manageability of a newly developed bone block and a deproteinized bovine bone block (Bio-Oss) for the treatment of localized bone defects in a dog model. Two male beagle dogs were used for this study. The mandibular premolars were extracted and two saddle-type defects were created bilaterally in the edentulous area. The defects were filled according to a randomized design with Bio-Oss bone block or with an equine hydroxyapatite plus collagen bone block (eHAC). Most control and test sites developed dehiscences during healing. After 4 weeks, the animals were euthanized and each hemimandible was prepared for histologic examination. No significant difference in terms of local tolerance was observed between test and control sites, and test and control sites showed similar histologic findings. However, a significant difference was noticed between the Bio-Oss block and the new bone block in terms of manageability. [ABSTRACT FROM AUTHOR]

A report of a patient who presented with severe disfigurement of the maxillary left lateral incisor and canine area following oncologic surgery is presented. The bone defect extended 20 mm from the cervical line of adjacent teeth up to and including the nasal cavity. Treatment was performed with a 1:1 ratio of autogenous bone graft (harvested from the retromolar region) and deproteinized bovine bone particles. The composite graft was hydrolyzed with recombinant human platelet-derived growth factor BB and covered with a titanium-reinforced nonresorbable membrane. Second-stage surgery was performed at 6 months, at which point the membrane was removed and two titanium dental implants were successfully placed. The elapsed time from initial surgery to definitive prosthesis placement was 14 months. [ABSTRACT FROM AUTHOR]

This study used backscattered electron microscopy (BSE-SEM) to analyze specimens in which bone was augmented both horizontally and vertically with a xenograft scaffold and recombinant human platelet-derived growth factor (rhPDGF-BB), with or without a resorbable collagen membrane. The study objective was to compare percentage weight and volume calcium-phosphorus ratios of regenerated bone and native bone and the nature of the bony contact with two different implant surfaces. Examination of the nature of the mineralized tissues by BSE-SEM provides an understanding of the composition and element ratio of bone regenerated from nonautogenous grafts. The data collected demonstrated no statistically significant difference between regenerated bone and native bone in the two tested groups. Our observations suggest that bone regenerated via nonautogenous grafts displays composition, structure, and physical properties very similar to those of native bone. Similarly, no significant differences were observed at the bone-implant interface between bone regenerated proximal to oxidized versus machined implants. [ABSTRACT FROM AUTHOR]

The present paper reports on two patients who underwent three-dimensional ridge augmentation using a xenograft in combination with recombinant human platelet-derived growth factor-BB (rhPDGF-BB). Patient 1 received a deproteinized bovine block infused with PDGF and secured to the alveolar crest by two fixation screws to augment the crest horizontally. After 5 months, implants were successfully placed. Patient 2 underwent a vertical ridge augmentation procedure that combined deproteinized bovine bone particles embedded in a collagen matrix soaked in PDGF Three titanium dental implants were placed in each patient 5 months later. Clinical and histologic results showed excellent soft and hard tissue healing. Bone had regenerated throughout the whole area and the xenograft particles were embedded in bone, which presented resorption lacunae close to areas with ongoing bone formation. This indicated that, in augmented areas, intense physiologic remodeling was ongoing. No data exist concerning three-dimensional bone augmentation using PDGF and a xenograft in humans. This report suggests that the use of rhPDGF-BB in combination with a deproteinized bovine graft may have the potential to regenerate large three-dimensional alveolar defects in humans. [ABSTRACT FROM AUTHOR]

The primary objective of this proof-of-principle study was to evaluate the outcome of vertical ridge augmentation in a standardized dog model by combining purified recombinant platelet-derived growth factor (rhPDGF-BB) and a block of deproteinized cancellous bovine bone. The secondary objective was to determine the value of a resorbable barrier membrane to improve the efficacy of the procedure. Six adult foxhounds were committed to bilateral surgical extraction of all four mandibular premolars. A vertical alveolar ridge defect was created at the time of the extractions. Three months later, the artificially created defects were grafted: Group A used a deproteinized bovine bone block in combination with a collagen barrier membrane, group B used a deproteinized bovine bone block infused with rhPDGF-BB only, and group C included a deproteinized bovine bone block infused with rhPDGF-BB, plus a collagen resorbable barrier membrane. After 4 months, the animals were sacrificed. Histologic examination of group B revealed a large amount of newly formed bone, and a large amount of bone-to-implant contact was visible in the areas of bone regeneration extending over the top of the implant cover screw. The results of this preclinical canine study provide proof-of-principle that rhPDGF-BB, used in combination with a deproteinized bovine block without placement of a barrier membrane, has the potential to regenerate significant amounts of new bone in severe mandibular ridge defects. In addition, the results seem to point to the importance of the periosteum as a source of osteoprogenitor cells in growth factor-mediated regenerative procedures. [ABSTRACT FROM AUTHOR]

The aim of this case report was to evaluate the ability of Bio-Oss used together with an expanded polytetrafluoroethylene, titanium-reinforced membrane to restore a vertical bone defect. Bio-Oss served as a filler material. After the membrane was removed, screw-type implants were placed. During this phase, cylindric bone samples were retrieved from the augmented area for histologic examination. The biopsy samples were composed of low-density trabecular bone with numerous interspersed graft particles. Clinical and histologic results demonstrated that this surgical technique could be a successful and predictable procedure for rebuilding a resorbed ridge to place implants. [ABSTRACT FROM AUTHOR]

The objective of this investigation was to determine the fate of thin buccal bone encasing the prominent roots of maxillary anterior teeth following extraction. Resorption of the buccal plate compromises the morphology of the localized edentulous ridge and makes it challenging to place an implant in the optimal position for prosthetic restoration. In addition, the use of Bio-Oss as a bone filler to maintain the form of the edentulous ridge was evaluated. Nine patients were selected for the extraction of 36 maxillary anterior teeth. Nineteen extraction sockets received Bio-Oss, and seventeen sockets received no osteogenic material. All sites were completely covered with soft tissue at the conclusion of surgery. Computerized tomographic scans were made immediately following extraction and then at 30 to 90 days after healing so as to assess the fate of the buccal plates and resultant form of the edentulous sites. The results were assessed by an independent radiologist, with a crest width of 6 mm regarded as sufficient to place an implant. Those sockets treated with Bio-Oss demonstrated a loss of less than 20% of the buccal plate in 15 of 19 test sites (79%). In contrast, 12 of 17 control sockets (71%) demonstrated a loss of more than 20% of the buccal plate. In conclusion, the Bio-Oss test sites outperformed the control sites by a significant margin. No investigator was able to predict which site would be successful without the grafting material even though all were experienced clinicians. This leads to the conclusion that a patient has a significant benefit from receiving grafting materials at the time of extraction. [ABSTRACT FROM AUTHOR]

This study evaluated the clinical, radiographic, and histologic response to the composite use of Bio-Oss porous bone mineral and autogenous bone in combination with a Bio-Gide bilayer collagen membrane to achieve regeneration when treating human periodontal bone defects. Preoperative recordings for four treatment areas included radiographs, clinical probing depths, and attachment levels; these recordings were repeated at 9 months. Histologic evaluation revealed new cementum with inserting collagen fibers and new bone formation on the surface of both types of graft materials. This grafting combination not only compared favorably with the previous use of Bio-Oss and Bio-Gide, but exceeded that result with almost complete periodontal regeneration. This human histologic study demonstrates that autogenous bone in combination with porous bone mineral matrix, together with the Bio-Gide collagen membrane, has the capacity to stimulate substantial new bone and cementum formation with Sharpey's fiber attachment. [ABSTRACT FROM AUTHOR]

A technique enabling the study of adherence occurring among implant materials and epithelial and connective cells cultured in vitro and freshly obtained from explants of human gingival tissue is described. The data show that cell adherence to titanium alloy is influenced by the modality of implant surface preparation. [ABSTRACT FROM AUTHOR]

This study compared clinical microbiologic, and morphostructural aspects of the healing process in clinical cases treated with expanded polytetrafluoroethylene membranes placed in fresh extraction sockets, which did or did not show early membrane exposure. The examination was focused particularly on morphology of the microbic population and its ability to penetrate membrane pores. Results of the study suggest that use of the membranes is effective in the treatment of fresh extraction sockets with osseointe grated implants; that the membranes are highly biocompatible with gingival tissues; and that early exposure of the membranes during healing hinders the effectiveness of guided tissue regeneration in peri-implant tissues. [ABSTRACT FROM AUTHOR]

Article 146 (e) of the Romanian Constitution stipulates the power of the Constitutional Court to solve legal disputes of a constitutional nature between public authorities. Thus, the Constitutional Court solves or settles constitutional disputes between the authorities belonging to the three powers in the state. These situations may concern disputes between two or more constitutional authorities regarding the content or length of their powers, as provided for by the Constitution. The result sought is to overcome possible institutional blockages. From 2005, when the Constitutional Court of Romania first decided on such dispute, and until today, thirteen decisions for settling certain disputes between the President of Romania and other public authorities have been issued. The multitude of disputes is due, primarily, to the semi-presidential system of government provided for by the Constitution and to the ambiguous provisions regarding the division of powers between the Romanian President, Government, Parliament and the judicial power. Last but not least, this dispute is due to a certain political context, too. The present paper aims to analyze the case-law of the Constitutional Court of Romania regarding the constitutional legal disputes between the President of Romania and other public authorities, as well as its impact on the constitutional order and the relationships between the public authorities from the checks and balances system. [ABSTRACT FROM AUTHOR]