Guided Bone Regeneration Therapy Research Articles

Occlusive membranes for guided regeneration of inflamed tissue defects

Guided bone regeneration aided by the application of occlusive membranes is a promising therapy for diverse inflammatory periodontal diseases. Symbiosis, homeostasis between the host microbiome and cells, occurs in the oral environment under normal, but not pathologic, conditions. Here, we develop a symbiotically integrating occlusive membrane by mimicking the tooth enamel growth or multiple nucleation biomineralization processes. We perform human saliva and in vivo canine experiments to confirm that the symbiotically integrating occlusive membrane induces a symbiotic healing environment. Moreover, we show that the membrane exhibits tractability and enzymatic stability, maintaining the healing space during the entire guided bone regeneration therapy period. We apply the symbiotically integrating occlusive membrane to treat inflammatory-challenged cases in vivo, namely, the open and closed healing of canine premolars with severe periodontitis. We find that the membrane promotes symbiosis, prevents negative inflammatory responses, and improves cellular integration. Finally, we show that guided bone regeneration therapy with the symbiotically integrating occlusive membrane achieves fast healing of gingival soft tissue and alveolar bone.

Incorporation of Magnesium and Zinc Metallic Particles in PLGA Bi-layered Membranes with Sequential Ion Release for Guided Bone Regeneration.

Guided bone regeneration (GBR) membranes are commonly used for periodontal tissue regeneration. Due to the complications of existing GBR membranes, the design of bioactive membranes is still relevant. GBR membranes with an asymmetric structure can accommodate the functional requirements of different interfacial tissues. Here, poly(lactic acid-glycolic acid) (PLGA) was selected as the matrix for preparing a bi-layered membrane with both dense and porous structure. The dense layer for blocking soft tissues was incorporated with zinc (Zn) particles, while the porous layer for promoting bone regeneration was co-incorporated with magnesium (Mg) and Zn particles. Mg/Zn-embedded PLGA membranes exhibited 166% higher mechanical strength in comparison with pure PLGA membranes and showed suitable degradation properties with a sequential ion release behavior of Mg2+ first and continuously Zn2+. More importantly, the release of Zn2+ from bi-layered PLGA endowed GBR membranes with excellent antibacterial activity (antibacterial rate > 69.3%) as well as good cytocompatibility with MC3T3-E1 (mouse calvaria pre-osteoblastic cells) and HGF-1 (human gingival fibroblast cells). Thus, the asymmetric bi-layered PLGA membranes embedded with Mg and Zn particles provide a simple and effective strategy to not only reinforce the PLGA membrane but also endow membranes with osteogenic and antibacterial activity due to the continuous ion release profile, which serves as a promising candidate for use in GBR therapy.

Chitosan-based hydrotalcite nanostructured membranes containing sodium alendronate for guided bone regeneration therapy

Chitosan-based hydrotalcite nanostructured membranes containing sodium alendronate for guided bone regeneration therapy

Reabilitação oral a partir de uma abordagem interdisciplinar

Rehabilitation Implantology can be a safe alternative for solving complex cases, especially when working in an interdisciplinary way with other specialties. The objective of this article is to describe a clinical case of oral rehabilitation of a 33-year-old female patient, with symptoms of inflammation and pain in element 24, due to failure in previous endodontic treatment. The image examination revealed root perforations, leakage of obturator material, periapical lesion, and loss of the buccal bone wall. In order to preserve as much bone structure as possible, element 24 was removed in a minimally traumatic way, starting with orthodontic apparatus 72 hours before extraction surgery. After extraction, guided bone regeneration therapy (GBR) was performed with a healing period of 8 months. Then, an implant was installed for subsequent rehabilitation with a single prosthesis. Interdisciplinary integration enabled the perfect reestablishment of the patients oral functions.

A long-lasting guided bone regeneration membrane from sequentially functionalised photoactive atelocollagen

The fast degradation of collagen-based membranes in the biological environment remains a critical challenge, resulting in underperforming Guided Bone Regeneration (GBR) therapy leading to compromised clinical results. Photoactive atelocollagen (AC) systems functionalised with ethylenically unsaturated monomers, such as 4-vinylbenzyl chloride (4VBC), have been shown to generate mechanically competent materials for wound healing, inflammation control and drug delivery, whereby control of the molecular architecture of the AC network is key. Building on this platform, the sequential functionalisation with 4VBC and methacrylic anhydride (MA) was hypothesised to generate UV-cured AC hydrogels with reduced swelling ratio, increased proteolytic stability and barrier functionality for GBR therapy. The sequentially functionalised atelocollagen precursor (SAP) was characterised via TNBS and ninhydrin colourimetric assays, circular dichroism and UV-curing rheometry, which confirmed nearly complete consumption of collagen's primary amino groups, preserved triple helices and fast (< 180 s) gelation kinetics, respectively. Hydrogel's swelling ratio and compression modulus were adjusted depending on the aqueous environment used for UV-curing, whilst the sequential functionalisation of AC successfully generated hydrogels with superior proteolytic stability in vitro compared to both 4VBC-functionalised control and the commercial dental membrane Bio-Gide®. These in vitro results were confirmed in vivo via both subcutaneous implantation and a proof-of-concept study in a GBR calvarial model, indicating integrity of the hydrogel and barrier defect, as well as tissue formation following 1-month implantation in rats. Statement of significanceCollagen-based membranes remain a key component in Guided Bone Regeneration (GBR) therapy, but their properties, e.g. proteolytic stability and soft tissue barrier functionality, are still far from optimal. This is largely attributed to the complex molecular configuration of collagen, which makes chemical accessibility and structure-function relations challenging. Here, we fabricated a UV-cured hydrogel network of atelocollagen, whereby triple helices were sequentially functionalised with two distinct ethylenically unsaturated monomers. The effects of the sequential functionalisation and UV-curing on the macroscopic properties, degradation behaviour and GBR capability were investigated in vitro and in vivo. The results highlight the key role of the sequential functionalisation and provide important insights for the design of future, longer-lasting resorbable membranes for GBR therapy.

Structure, Barrier Function, and Bioactivity of Platelet-Rich Fibrin Following Thermal Processing.

Platelet-rich fibrin (PRF) has been utilized as a substitute for resorbable membranes during guided bone regeneration therapy as it is a more bioactive biomaterial with living cells and growth factors than resorbable membranes. Nevertheless, PRF poses obvious disadvantages in its mechanical strength since its rapid degradability has been shown to typically resorb within a 2-week time period. In the present study, the barrier function and biological and mechanical properties of PRF were investigated both as standard therapy and after thermal processing. Two heating processes were applied: both single-side heating and double-side heating at 90°C for 10 s using a metal plate heater. The appearance and weight of PRF membranes were documented after heating, along with their morphological and mechanical properties evaluated by scanning electron microscope and tensile strength tests. The viability of cells found within PRF membranes was also evaluated using live/dead cell viability and CCK-8 (cell counting kit-8) assays. To comprehensively evaluate the barrier function of PRF membranes, Hoechst staining of human gingival fibroblasts, which can be distinguished from cells within the PRF membrane by emitting blue light at an excitation wavelength of 488 nm, was seeded onto the surface of PRF membranes. Furthermore, osteoblasts were cultured with extracts from different PRF groups to evaluate the biocompatibility of PRF membranes. The degradation rate of PRF membranes was examined by digestion assay. Compared with the nonheated PRF control, the size and weight of PRF membranes led to a significant decrease with a denser PRF microstructure following heating. In summary, the double-sided heating of PRF membranes not only demonstrated an improvement in mechanical and degradation properties but also led to a decrease in cell viability and proliferation.

Development of Zoledronic Acid Containing Biomaterials for Enhanced Guided Bone Regeneration.

In recent years, biomaterial-based treatments, also called guided bone regeneration (GBR), which aim to establish a bone regeneration site and prevent the migration of gingival connective tissue and / or peripheral epithelium through the defective area during periodontal surgical procedures have come to the fore. In this report, we have developed a nanoparticle bearing thermosensitive in situ gel formulation of Pluronic F127 and poly(D,L-lactic acid) based membrane to reveal their utilization at GBR by in-vivo applications. In addition, the encouragement of the bone formation in defect area via inhibition of osteoclastic activity is intended by fabrication these biodegradable biomaterials at a lowered Zoledronic Acid (ZA) dose. Both of the developed materials remained stable under specified stability conditions (25°C, 6 months) and provided the extended release profile of ZA. The in-vivo efficacy of nanoparticle bearing in situ gel formulation, membrane formulation and simultaneous application for guided bone regeneration was investigated in New Zealand female rabbits with a critical size defect of 0.5×0.5cm in the tibia bone for eight weeks. Based on the histopathological findings, lamellar bone and primarily woven bone formations were observed after 8 weeks of post-implantation of both formulations, while fibrosis was detected only in the untreated group. Lamellar bone growth was remarkably achieved just four weeks after the simultaneous application of formulations. Consequently, the simultaneous application of ZA-membrane and ZA-nanoparticles loaded in-situ gel formulations offers enhanced and faster GBR therapy alternatives.

Expresión del marcador óseo CD44 en hueso alveolar previamente injertado.

Objetive: To determine the expressions of the bone surface marker CD44 in samples of alveolar bone pr iously regenerated with allograft, xenograft, and mixed, using the technique of guided bone regeneration. Material and Methods: This exploratory study was approved by the institutional research and ethics committee. By means of intentional sampling and after obtaining informed consent for tissue donation, 20 samples of alveolar bone previously regenerated with guided bone regeneration therapy with particulate bone graft and membrane were taken during implant placement. The samples were stained with hematoxylin-eosin for histological analysis, and by immunohistochemistry for the detection of CD44. Results: Sections with hematoxylin-eosin showed bone tissue with the presence of osteoid matrix and mature bone matrix of usual appearance. Of the CD44+ samples, 80% were allograft and 20% xenograft. The samples with allograft-xenograft were negative. There were no differences in the intensity of CD44 expression between the positive samples. The marker was expressed in osteocytes, stromal cells, mononuclear infiltrate, and some histiocytes. Eighty percent of the CD44+ samples and 100% of the samples in which 60 or more cells were labelled corresponded to allografts (p=0.000). A total of 67% of the samples from the anterior sector, and 40% from the posterior sector were CD44+ (p=0.689). Conclusion: This study shows for the first time that guided bone regeneration using allografts is more efficient for the generation of mature bone determined by the expression of CD44, compared to the use of xenografts and mixed allograft-xenograft, regardless of the regenerated anatomical area.

A pure zinc membrane with degradability and osteogenesis promotion for guided bone regeneration: In vitro and in vivo studies

Selection of an appropriate membrane material for guided bone regeneration (GBR) is still ongoing among resorbable and nonresorbable membranes with different characteristics. The major problem with nonresorbable membranes is the inevitable secondary surgery, while resorbable polymer membranes have limitations in providing sufficient mechanical support during the bone repair period due to premature loss of mechanical strength. Pure magnesium foil has been evaluated to explore its feasibility as a resorbable GBR membrane. It exhibited better mechanical properties, whereas poor formability and fast degradation rate were noted. In light of this, pure zinc membrane was developed as a pilot research in this paper. We designed three types of pure zinc membranes: pure Zn without pores, pure Zn with 300µm diameter and 1000µm diameter pores, and pure titanium without pores as a control. The mechanical property, in vitro immersion tests, and MC3T3-E1 cell viability assays were tested. Moreover, in vivo behaviors of three type zinc membranes were evaluated by using a rat calvarial critical-sized bone defect model. The experimental results indicated that pure Zn membrane with 300µm pores showed the most favorable osteogenic capability, comparable to that of titanium membrane without pores. Therefore, considering appropriate degradation rate, adequate mechanical maintenance, and profitable osteogenic capacity, metallic pure zinc is believed to be a promising candidate for barrier membranes in GBR therapy for bone regeneration, and its mechanical property can be enhanced with further alloying. STATEMENT OF SIGNIFICANCE: Metallic element zinc plays a pivotal role in the growth and mineralization of bone tissues. As a pilot research, three type of guided bone regeneration (GBR) membranes were developed in the present work: pure Zn without pores, pure Zn with 300µm-diameter and 1000µm-diameter pores respectively. The mechanical property, in vitro immersion tests and MC3T3-E1 cell viability assays were tested, with pure titanium without pores as a control, thereafter the in vivo performance were evaluated by using a rat calvarial critical-sized bone defect model. It indicated that pure Zn membrane with 300µm pores showed the most favorable osteogenic capability, comparable to that of titanium membrane control, and is believed to be a promising material candidate as barrier membrane in GBR therapy for bone regeneration.

Multilayered Titanium Carbide MXene Film for Guided Bone Regeneration.

PurposeMXenes are two-dimensional (2D) materials that are increasingly being applied in biomedical fields. This is ascribed to their good physiochemical properties, unique structure and high biological compatibility. However, the osteogenic activity and suitability of these materials for bone tissue engineering are not clearly understood. Thus, the aim of this study is to evaluate the biocompatibility, osteoinductivity and guided bone regeneration ability of Ti3C2Tx MXene in vitro and in vivo.MethodsMultilayered Ti3C2Tx MXene films were prepared and characterized by XRD and SEM. In vitro experiments were performed to evaluate the effect of MXene films on cell adhesion and morphology with SEM and fluorescence microscopy. The cytotoxicity of MXene films was detected with the Live/Dead double-staining tests. The EdU assay was employed to evaluate cell proliferation on MXene films and ALP activity was tested to determine the effect of the films on osteogenic differentiation in vitro. The mRNA expression of osteogenic differentiation-related markers was measured using qRT-PCR. In vivo animal studies were performed in which the MXene films were implanted subcutaneously in rats to evaluate biocompatibility and host tissue response in vivo. In addition, a rat calvarial defect model was established to examine the bone regeneration performance of the Ti3C2Tx MXene films. The specimens were analyzed with micro-CT evaluation and histological tests.ResultsThe XRD and SEM analyses revealed that the Ti3C2Tx MXene film was successfully synthesized. The cellular experiments showed that MXene films were highly cytocompatible and enhanced osteogenic differentiation in vitro. When implanted into subcutaneous sites and calvarial defect sites in rats, MXene films showed good biocompatibility, osteoinductivity and bone regeneration activity in vivo.ConclusionIn summary, this study presents new applications of MXenes in bone tissue engineering and in guided bone regeneration therapy.

In vitro evaluation of electrospun PLGA/PLLA/PDLLA blend fibers loaded with naringin for guided bone regeneration.

The present study was to evaluate fiber mesh loaded with naringin via electrospinning to guide bone regeneration in vitro. The naringin-loaded fiber mesh was prepared via elctrospinning of PLGA, PLLA, PDLLA blending solution with naringin. SEM showed that naringin decreased the fiber's diameter according to the concentration of naringin. After 20 days' degradation in PBS, the drug-loaded fiber meshes still kept their stability with about 10% decrease in tensile strength. In vitro release experiments showed a sustained and steady naringin releasing profile with little initial burst releasing. Compared to the mats without naringin, the fiber mats loaded with naringin showed the most pronounced enhancement of cell growth when MC3T3-E1 cells were cultured on the fiber mats. The blend fiber loaded with naringin has optimized physical properties and sustained release profile in vitro. The study presents a promising fibrous mesh material for guided bone regeneration therapy.

The Everted Flap: Preliminary Results

Introduction: Attainment of primary soft tissue closure at the time of guided bone regeneration (GBR) therapy often requires significant crestal repositioning of the buccal mucoperiosteal flap, resulting in compromise of the buccal vestibule and loss of mucogingival confluence in the area. The everted flap technique (EFT) is used at the time of extraction of teeth demonstrating bone loss beyond their apices and complete epithelialization of the extraction socket. The EFT uses the tissues within the extraction socket as part of the buccal mucoperiosteal flap, thus obviating the need for crestal mucoperiosteal flap repositioning after placement of regenerative material and covering membranes.Case Presentation: Out of 118 patients treated using the EFT in the authors' private practices, one primary case and two supplementary cases are presented here. Soft tissue primary closure was attained and maintained throughout the course of regeneration in all patients. No patients required repositioning of a buccal mucoperiosteal flap at a second surgical visit to reform the buccal vestibule and/or reestablish mucogingival confluence in the area.Conclusion: The EFT offers a means by which to help attain passive soft tissue primary closure after GBR therapy without crestal repositioning of the buccal mucoperiosteal flap and to lessen the need for buccal soft tissue repositioning.

Evaluation of Guided Bone Regeneration around Oral Implants over Different Healing Times Using Two Different Bovine Bone Materials: A Randomized, Controlled Clinical and Histological Investigation.

To evaluate the potential of two bone substitute materials and the influence of different healing periods in guided bone regeneration therapy of osseous defects around implants. Twenty-four edentulous patients received implants in the region of the lost lower incisors. Around two standardized osseous defects were created, treated either with a 50:50 mixture of PepGen P-15® and OsteoGraf®/N-700 (test group) or with BioOss® (control group), and covered with titanium membranes. After healing periods of 2, 4, 6, or 9 months, the implants were removed together with the surrounding bone and subsequently prepared for histological evaluations. Defect depths in both groups showed a clinical reduction after intervention. The histologically measured distance from the implant shoulder to the first point of bone-implant contact (BIC) after treatment did not differ between the two groups. The healing time influenced the level of the first point of BIC, with a longer healing period producing a more coronal first point of BIC. A greater percentage BIC and a higher fraction of mineralized bone were found in the pristine bone area compared with the augmented defect area. It can be concluded that in the treatment of osseous defects around oral implants, both materials were equally effective bone substitute materials when used in combination with guided bone regeneration.

Histometric analysis of alveolar bone regeneration with expanded polytetrafluoroethylene (e-PTFE) and latex membranes

Aim: To investigate the amount of connective tissue migrated into the extraction socket using EPTFE and latex membranes. Methods: Seventeen rats were selected and randomly divided into 3 groups: e-PTFE membrane (n = 6), Latex membrane (n = 6) and Control (no membrane, n=5). After extraction of the maxillary right incisor, the animals of the test groups were subjected to alveolar guided bone regeneration (GBR) surgery and received an expanded polytetrafluoroethylene (e-PTFE) and a latex membrane, respectively. Thirty days after surgery, the animals were killed and histometric analysis was done to evaluate the migration of connective tissue. Data were analyzed statistically by one-way ANOVA and multiple-comparison Tukey’s test at 5% significance level. Results: There was statistically significant difference between groups ePTFE and Latex (p=0.001), and between groups e-PTFE and Control (p=0.012), but no significant difference was found between groups Latex and Control (p=0.416). Conclusions: The ePTFE membrane showed better results and appeared more adequate for GBR therapy, forming a barrier to prevent the migration of connective tissue into the extraction socket. The latex membrane, on the other hand, did not show benefits over the control group.

Stem Cell Therapy for Craniofacial Bone Regeneration: A Randomized, Controlled Feasibility Trial

Stem cell therapy offers potential in the regeneration of craniofacial bone defects; however, it has not been studied clinically. Tissue repair cells (TRCs) isolated from bone marrow represent a mixed stem and progenitor population enriched in CD90- and CD14-positive cells. In this phase I/II, randomized, controlled feasibility trial, we investigated TRC cell therapy to reconstruct localized craniofacial bone defects. Twenty-four patients requiring localized reconstruction of jawbone defects participated in this longitudinal trial. For regenerative therapy, patients were randomized to receive either guided bone regeneration (GBR) or TRC transplantation. At 6 or 12 weeks following treatment, clinical and radiographic assessments of bone repair were performed. Bone biopsies were harvested and underwent quantitative micro-computed tomographic (μCT) and bone histomorphometric analyses. Oral implants were installed, subsequently restored, and functionally loaded with tooth restorations. Reconstructed sites were assessed for 1 year following therapy. No study-related, serious adverse events were reported. Following therapy, clinical, radiographic, tomographic, and histological measures demonstrated that TRC therapy accelerated alveolar bone regeneration compared to GBR therapy. Additionally, TRC treatment significantly reduced the need for secondary bone grafting at the time of oral implant placement with a five fold decrease in implant bony dehiscence exposure (residual bone defects) as compared to GBR-treated sites(p < 0.01). Transplantation of TRCs for treatment of alveolar bone defects appears safe and accelerates bone regeneration, enabling jawbone reconstruction with oral implants. The results from this trial support expanded studies of TRC therapy in the treatment of craniofacial deformities (ClinicalTrials.gov number CT00755911).

Electrospun hydroxyapatite grafted poly(l-lactide)/poly(lactic-co-glycolic acid) nanofibers for guided bone regeneration membrane

To create new biodegradable guided bone regeneration (GBR) membranes, the composites of hydroxyapatite grafted poly(l-lactide) (HA-g-PLLA) nanoparticles and poly (l-lactide-co-glycolide) (PLGA) were prepared by electrospinning, and their corresponding properties were evaluated including morphology, thermodynamics, mechanics, wettability, degradation, bioactivity, and biocompatibility. At 5 wt% HA-g-PLLA, the nanoparticles evenly distributed in the fibers and the composite fiber membranes showed higher strength properties compared to pristine PLGA and HA/PLGA. However, as the HA-g-PLLA content increased, the nanoparticles began to aggregate, which resulted in the deterioration of mechanics properties of the composite fiber membrane. The degradation and bioactivity of the composite fiber membrane were depended strongly on the HA-g-PLLA contents. With HA-g-PLLA contents going up, degradation rate speeded up due to the increased wettability of the composite fibers and the decreased crystallinity of PLGA matrix. The analysis for different soaking periods in SBF demonstrated the growth of a hydroxyapatite-like layer on the composite surfaces. The biocompatibility of the composite fiber membranes were assessed by the cell attachment. The osteoblasts adhered and spread on the composite membranes of 20 wt% HA-g-PLLA were higher than the other composites. These results suggested that the bioresorbable HA-g-PLLA/PLGA composite fiber membranes could be utilized for GBR therapy.

Treatment of an early failing implant by guided bone regeneration using resorbable collagen membrane and bioactive glass

Implant failure can be divided into early (prior to prosthetic treatment) or late (after prosthetic rehabilitation). Early failure is generally due to interference in the healing process after implant placement. Implants undergoing early failure will show progressive bone loss on radiographs during the healing period (4 to 6 weeks). In the present case report, early progressive bone loss was seen at 6 weeks, after placement of a non-submerged single piece mini implant. Clinical examination revealed peri-implant bleeding on probing and pocket and grade-1 mobility. Treatment protocol included mechanical debridement (plastic curettes), chemical detoxification with supersaturated solution of citric acid, antibiotics and guided bone regeneration therapy using the collagen membrane as guided bone regeneration barrier in combination with bioactive glass as bone grafting material. The 6 month postoperative examination showed complete resolution of the osseous defect, thus suggesting that this technique may hold promise in the treatment of implants undergoing early failure.

Guided Bone Regeneration: biological principle and therapeutic applications

The Guided Bone Regeneration (GBR) treatment concept advocates that regeneration of osseous defects is predictably attainable via the application of occlusive membranes, which mechanically exclude non-osteogenic cell populations from the surrounding soft tissues, thereby allowing osteogenic cell populations originating from the parent bone to inhabit the osseous wound. The present review discusses the evolution of the GBR biological rationale and therapeutic concept over the last two decades. Further, an overview of the GBR research history is provided with specific focus on the evidence available on its effectiveness and predictability in promoting the regeneration of critical size cranio-maxillo-facial defects, the neo-osteogenesis potential and the reconstruction of atrophic alveolar ridges before, or in conjunction with, the placement of dental implants. The authors conclude that future research should focus on (a) the investigation of the molecular mechanisms underlying the wound healing process following GBR application; (b) the identification of site and patient related factors which impact on the effectiveness and predictability of GBR therapy and (c) the evaluation of the pathophysiology of the GBR healing process in the presence of systemic conditions potentially affecting the skeletal system.

Maintaining Primary Closure After Guided Bone Regeneration Procedures: Introduction of a New Flap Design and Preliminary Results

Various flap designs have been proposed by numerous authors for the maintenance of passive primary soft tissue closures following guided bone regeneration (GBR) procedures. A previous publication by the present author documented the maintenance of passive soft tissue primary closures 96.1% of the time at least 6 months after GBR therapy in all areas of the mouth. Although seemingly impressive, a 96.1% success rate means that there is premature membrane exposure 3.9% of the time. A new flap design is introduced for use in conjunction with previously described flap designs to lessen the incidence of premature membrane exposure. A total of 173 sites treated with GBR therapy were examined up to 6 months postoperatively to assess the ability to maintain passive soft tissue primary closure. Any membrane exposure during this 6-month postoperative period was deemed a failure, even if the site was successfully treated with an implant placement and restoration. A total of 171 of 173 GBR-treated sites demonstrated the maintenance of a soft tissue passive primary closure 6 months postoperatively, yielding a success rate of 98.8%. The introduction of the proposed flap design for use in conjunction with previously described flap designs significantly reduced the incidence of premature membrane exposure after a variety of GBR procedures.

Bone reaction to bovine hydroxyapatite grafted in the mandibular defects of beagle dogs

Guided bone regeneration(GBR) is a well-established technique, both in the reconstructing of atrophic alveolar bone prior to implant placement and around exposed implant surfaces at the time of implant installation. 1-4) For this promising technique, two basic components are needed membrane and graft material.1) The membranes itself placed and closely adapted around the defects can inhibit the nonosteogenic soft tissue cells and allow angiogenic and osteogenic cells from adjacent bone marrow to resolve the defects with bone tissue. But GBR therapy using membrane alone has encountered some complications. One of them is a membrane collapse due to the soft tissue pressure during healing period, causing decreased the volume of created space. Several attempts have been made to solve the membrane collapse. The use of stiffer membrane, i.e. titanium-reinforced e-PTFE membrane 5) , or membrane supporting devices such as stainless steel microscrew1 is one of them. Another method is the utilization of graft material. The graft material beneath the barrier membrane can support the occlusive membrane, stabilize the blood clot, and reduce the membrane shrinkage. In addition to its physical advantage, the graft material can influence the host response during healing. Graft materials are used for the purpose of encouraging new bone formation by a variety of process osteogenesis, osteoinduction, osteoconduction. Autogenous bone is the only graft material known to induce bone formation through osteogenesis. Allogenic