Osteoinductive, morphologic, and biomechanical properties of autolyzed, antigen-extracted, allogeneic human bone

Establishing a bone bank within a hospital setting in India: early insights from a tertiary care center in Northern India-a review article

When addressing bone defects resulting from trauma, infection, or tumors, the use of allogenic bone is often necessary. While autografts are considered the standard, they have limitations and can lead to donor site morbidity. Consequently, there has been exploration into the feasibility of utilizing allogenic bone and bone graft replacements. Allogenic bone transplants are acquired from donors following rigorous procurement, sterile processing, and donor screening procedures. To ensure the safe storage and effective utilization of allograft material, a bone banking system is employed. Establishing and managing an orthopedic bone bank, entails navigating complex legal and medical organizational aspects. This paper examines the establishment and operation of bone banks in India, drawing upon our first-hand experience in managing one at a tertiary care center in Northern India.Level of evidence: Level IV.

Allogenic Bone Graft in Dentistry: A Review of Current Trends and Developments

In an effort to prepare non-autologous bone graft or biomaterial that would possess characteristics comparable to autologous bone, many different allogenic bone derivatives have been created. Although different existing processing methods aim to achieve the very same results, the specific parameters applied during different stages material preparation can result in significant differences in the material's mechanical and biological properties The properties, including osteoconductive, osteoinductive, and even osteogenic potential, can differ vastly depending on particular preparation and storage techniques used. Osteogenic properties, which have long been thought to be characteristic to autogenic bone grafts only, now seem to also be achievable in allogenic materials due to the possibility to seed the host's stem cells on a graft before its implantation. In this article, we aim to review the available literature on allogenic bone and its derivatives as well as the influence of different preparation methods on its performance.

Effect of minor amounts of β-calcium pyrophosphate and hydroxyapatite on the physico-chemical properties and osteoclastic resorption of β-tricalcium phosphate cylinders

β-Tricalcium Phosphate (β-TCP), one of the most used bone graft substitutes, may contain up to 5 wt% foreign phase according to standards. Typical foreign phases include β-calcium pyrophosphate (β-CPP) and hydroxyapatite (HA). Currently, the effect of small amounts of impurities on β-TCP resorption is unknown. This is surprising since pyrophosphate is a very potent osteoclast inhibitor. The main aim of this study was to assess the effect of small β-CPP fractions (<1 wt%) on the in vitro osteoclastic resorption of β-TCP. A minor aim was to examine the effect of β-CPP and HA impurities on the physico-chemical properties of β-TCP powders and sintered cylinders. Twenty-six batches of β-TCP powder were produced with a Ca/P molar ratio varying between 1.440 and 1.550. Fifteen were further processed to obtain dense and polished β-TCP cylinders. Finally, six of them, with a Ca/P molar ratio varying between 1.496 (1 wt% β-CPP) and 1.502 (1 wt% HA), were incubated in the presence of osteoclasts. Resorption was quantified by white-light interferometry. Osteoclastic resorption was significantly inhibited by β-CPP fraction in a linear manner. The presence of 1% β-CPP reduced β-TCP resorption by 40%, which underlines the importance of controlling β-CPP content when assessing β-TCP biological performance.

A Comprehensive Microstructural and Compositional Characterization of Allogenic and Xenogenic Bone: Application to Bone Grafts and Nanostructured Biomimetic Coatings

Bone grafts and bone-based materials are widely used in orthopedic surgery. However, the selection of the bone type to be used is more focused on the biological properties of bone sources than physico-chemical ones. Moreover, although biogenic sources are increasingly used for deposition of biomimetic nanostructured coatings, the influence of specific precursors used on coating’s morphology and composition has not yet been explored. Therefore, in order to fill this gap, we provided a detailed characterization of the properties of the mineral phase of the most used bone sources for allografts, xenografts and coating deposition protocols, not currently available. To this aim, several bone apatite precursors are compared in terms of composition and morphology. Significant differences are assessed for the magnesium content between female and male human donors, and in terms of Ca/P ratio, magnesium content and carbonate substitution between human bone and different animal bone sources. Prospectively, based on these data, bone from different sources can be used to obtain bone grafts having slightly different properties, depending on the clinical need. Likewise, the suitability of coating-based biomimetic films for specific clinical musculoskeletal application may depend on the type of apatite precursor used, being differently able to tune surface morphology and nanostructuration, as shown in the proof of concepts of thin film manufacturing here presented.

New Perspectives in the Use of Biomaterials for Periodontal Regeneration

Periodontitis is a disease with a high prevalence among adults. If not treated, it can lead to loss of teeth. Periodontal therapy aims at maintaining patient’s teeth through infection control and correction of non-maintainable anatomies including—when possible—regeneration of lost periodontal tissues. The biological regenerative potential of the periodontium is high, and several biomaterials can be utilized to improve the outcome of periodontal therapy. Use of different natural and synthetic materials in the periodontal field has been studied for many years. The main materials used today in periodontology analyzed in this review are: Resorbable and non-resorbable barrier membranes; autogenous, allogeneic, xenogeneic, and alloplastic bone substitutes; biological agents, such as amelogenins; platelet-derived growth factor; bone morphogenic proteins; rh fibroblast growth factor 2; teriparatide hormone; platelet concentrates; and 3D scaffolds. With the development of new surgical techniques some concepts on periodontal regeneration that were strictly applied in the past seem to be not so critical today. This can have an impact on the materials that are needed when attempting to regenerate lost periodontal structures. This review aims at presenting a rationale behind the use of biomaterials in modern periodontal regeneration

Evaluation of Cyclosporine A with β-TCP in the Treatment of Human Infra bony Defects - A Randomized Controlled Pilot Study

INTRODUCTION

Cyclosporine A (CsA), an immunosuppressant, is considered a life saver drug in organ transplant cases. It has also been tested in animal and human studies for periodontal applications as it selectively inhibits T lymphocyte proliferation, Interleukin-2 (IL-2) and other cytokine production, without any effect on T suppressor cells, thereby suppressing the cell mediated immunity and suppressing the inflammation. Inflammatory and immunological responses have been found to be decreased and bone formation is found to be increased in immunosuppressed animals. CsA is also supposed to potentiate osseous regeneration due to increase in the bone alkaline phosphatase levels and a direct activating effect on osteoblasts.

AIM

The present study was aimed at evaluating locally administered low dose of CsA which is potent immunosuppressant along with β-Tricalcium phosphate (β-TCP) in comparison with β TCP alone, in the treatment of human infrabony defects, over a period of six months.

MATERIALS AND METHODS

Thirty two systemically healthy chronic periodontitis patients with infrabony defects were included in the randomized, controlled, parallel arm study and were allocated into either Group A (n =16), patients treated with β-TCP + CsA (2 mg) or Group B (n =16), patients treated with β-TCP. Clinical parameters [Relative Attachment Level (RAL), Probing Depth (PD), Gingival Recession (GR)] and radiographic parameters were measured at baseline and six months postoperatively. Statistical analysis was done using SPSS version 16 software. Student's paired and independent t-test were used for intra and inter-group analysis.

RESULTS

Both Group A and Group B showed statistically significant improvements in clinical and radiographic parameters from base line to six months post-operatively. The Clinical Attachment Level (CAL) gain, Linear Bone Growth (LBG) and Percentage Bone Fill (% BF) were 2.38±1.12 mm, 1.90±1.48 mm and 49.83±29.23 mm in Group A and 2.57±1.22 mm, 2.03±1.16 mm and 62.84±29.70 mm in Group B respectively, inter group comparison showed no statistically significant difference.

CONCLUSION

Both the groups revealed statistically significant improvement in clinical and radiographic parameters and adjunctive use of CsA did not prove beneficial.

Rapid prototyping-assisted maxillofacial reconstruction

Rapid prototyping (RP) technologies have found many uses in dentistry, and especially oral and maxillofacial surgery, due to its ability to promote product development while at the same time reducing cost and depositing a part of any degree of complexity theoretically. This paper provides an overview of RP technologies for maxillofacial reconstruction covering both fundamentals and applications of the technologies. Key fundamentals of RP technologies involving the history, characteristics, and principles are reviewed. A number of RP applications to the main fields of oral and maxillofacial surgery, including restoration of maxillofacial deformities and defects, reduction of functional bone tissues, correction of dento-maxillofacial deformities, and fabrication of maxillofacial prostheses, are discussed. The most remarkable challenges for development of RP-assisted maxillofacial surgery and promising solutions are also elaborated.

Efficacy of Platelet-Rich-Plasma (PRP) and Highly Purified Bovine Xenograft (Laddec(®)) Combination in Bone Regeneration after Cyst Enucleation: Radiological and Histological Evaluation

Objectives

The purpose of the present study was to evaluate the efficacy of adding platelet-rich plasma (PRP) to a new highly purified bovine allograft (Laddec^®) in the bone regeneration of cystic bony defects augmented following cystectomy.

Material and Methods

Study sample included 20 patients undergoing cystectomy in which the bone defect was filled with PRP and Laddec^®. All patients were examined with periapical radiographs before operation and at follow-up. After 3 months, at re-entry surgery for implant placement, bone core was taken for histological and histomorphometric analysis.

Results

The postoperative successive radiographs showed a good regeneration of bone in the height of bony defects with application of PRP to bone graft. By the first postoperative month, about 48% of the defect was filled, which gradually increased in each month and showed about 90% of defect-fill by 6 months. Histological and histomorphometric analysis, showed a significant presence of bone tissue and vessels, with newly formed bone in contact with anorganic bone particles. The mean volume of vital bone was 68 ± 1.6% and the mean percentage of vital bone was 48 ± 2.4%. The mean percentage of inorganic particles in tissues was 20 ± 1.2% of the total volume. All the samples analyzed did not evidence the presence of inflammatory cells.

Conclusions

The results of this study showed how the use of Laddec^® in association with platelet-rich plasma allows bone regeneration and has a potential for routine clinical use for regeneration of cystic bony defects.

Alveolar ridge preservation with the socket-plug technique utilizing an alloplastic putty bone substitute or a particulate xenograft: a histological pilot study

Following tooth extraction, ridge preservation procedures are employed to regenerate bone in the extraction socket, limit consequent ridge resorption, and provide a stable base for implant placement. The purpose of this study is to histologically evaluate and compare bone regeneration in extraction sockets grafted with either a putty alloplastic bone substitute or particulate anorganic bovine xenograft utilizing the socket-plug technique. Nineteen patients underwent 20 tooth extractions and ridge preservation following a standardized protocol. Ten sites were grafted with calcium phosphosilicate putty (CPS group) and the remaining 10 with anorganic bovine bone substitute (BO group). Patients were recalled after 4-6 months to evaluate the bone regeneration and to proceed with implant placement. A bone core was obtained during the implant procedure from each site and was used for histologic analysis. Histomorphometry revealed that residual graft values were significantly higher in the BO group (25.60% ± 5.89%) compared to the CPS group (17.40% ± 9.39%) (P < .05). The amount of new bone regenerated was also statistically significant higher in the alloplast group (47.15% ± 8.5%) as compared to the xenograft group (22.2% ± 3.5%) (P < .05). Results suggest that ridge preservation using a putty calcium phosphosilicate alloplastic bone substitute demonstrates more timely graft substitution and increased bone regeneration when compared to an anorganic bovine bone xenograft.

The use of fresh-frozen bone in oral surgery: a clinical study of 14 consecutive cases

BACKGROUND

Although autologous bone is considered the gold standard among the grafting materials used in implant therapy, it does have a number of drawbacks, in particular morbidity at the site of donation and the limited amount of bone available. To overcome these limitations a number of alternative bone materials have been employed in the last few years. In this study we report the results of the use of homologous fresh-frozen bone from a tissue bank in patients undergoing reconstruction of bone defects in the oral cavity.

MATERIAL AND METHODS

Between June 2004 and October 2008, 14 consecutive patients underwent bone reconstruction with fresh-frozen bone from a tissue bank. Four to eight months after surgery, implants were placed in the newly formed bone.

RESULTS

No problems were recorded during the post-operative course. In all cases treatment was successful and osteointegrated implants were placed in the newly formed bone after 4-8 months. All implants showed good osteointegration (100% overall success rate, mean follow-up 20 months), allowing loading with a fixed cemented prosthesis.

CONCLUSIONS

Our results support the previous findings that homologous fresh-frozen bone can be considered a valid alternative to autologous bone for the reconstruction of bone defects in the oral cavity in patients undergoing implant therapy.

The efficacy of host response modulation therapy (omega-3 plus low-dose aspirin) as an adjunctive treatment of chronic periodontitis (clinical and biochemical study)

BACKGROUND AND OBJECTIVE

Regeneration of lost periodontal tissues is considered to be one of the most challenging aspects of periodontal therapy. Our current understanding of the role of the host immuno-inflammatory response in periodontal diseases forms the basis of new therapeutic approaches. The aim of this study was to evaluate the efficacy of systemic administration of omega-3 polyunsaturated fatty acids plus low-dose aspirin as an adjunctive treatment to regenerative therapy of furcation defects.

MATERIAL AND METHODS

Forty patients displaying at least a single grade II furcation defect were enrolled in the study. They were randomly allocated into two groups: an experimental group receiving decalcified freeze-dried bone allograft (DFDBA) + omega-3 polyunsaturated fatty acids combined with low-dose aspirin; and a control group receiving DFDBA + placebo. Clinical parameters were monitored at baseline, and at 3 and 6 mo following therapy, and included plaque index, gingival index, gingival bleeding index, probing pocket depth and clinical attachment level. The biochemical markers assessed in gingival crevicular fluid samples were interleukin-1β and interleukin-10.

RESULTS

The experimental intervention resulted in a greater mean probing pocket depth reduction (P < 0.001) and gain in clinical attachment (P < 0.05) compared with the control at 6 mo. Furthermore, the experimental protocol was able to achieve a significant modulatory effect on the levels of interleukin-1β and interleukin-10 compared with control therapy.

CONCLUSION

The findings suggest that the combination therapy demonstrated successful reduction of gingival inflammation, reduction of pocket depth and attachment level gain, accompanied by a trend for modulation of the cytokines profile in gingival crevicular fluid.

Canal wall reconstruction and mastoid obliteration in canal wall down tympanomastoidectomized patients

CONCLUSION

Posterior canal reconstruction using autogenous bone pate and mastoid obliteration with allogenous cancellous bone chips (ACBCs) is a useful method to eliminate cavity problems after canal wall down tympanomastoidectomy (CWDT). It is also an appropriate method to obtain adequate middle ear space for hearing gain and to apply hearing aids for patients with poor eustachian tube function after surgery.

OBJECTIVE

This study was performed to suggest a new technique for posterior canal reconstruction and mastoid obliteration and to evaluate the outcome of the surgery.

PATIENTS AND METHODS

The entire posterior canal was reconstructed with autogenous bone pate, and the new isolated mastoid cavity was obliterated with ACBCs in patients who had undergone CWDT and suffered from cavity problems. Outcomes were measured by external auditory canal shape, condition of the neotympanum, hearing outcome, improvement of cavity problems, and surgical complications.

RESULTS

In 90.9%, the reconstructed canal wall maintained a cylindrical shape. The drum healed without perforation/retraction in 90.9%. The average air-bone gap value was 34.5 dB hearing level (HL) before the staged operation and 17.8 dB HL after the staged operation; 95.5% had no more cavity problems. Minor postauricular wound infection was the most common complication (13.6%).

Tissue engineering of autologous cartilage grafts in three-dimensional in vitro macroaggregate culture system

In the field of tissue engineering, techniques have been described to generate cartilage tissue with isolated chondrocytes and bioresorbable or nonbioresorbable biomaterials serving as three-dimensional cell carriers. In spite of successful cartilage engineering, problems of uneven degradation of biomaterial, and unforeseeable cell-biomaterial interactions remain. This study represents a novel technique to engineer cartilage by an in vitro macroaggregate culture system without the use of biomaterials. Human nasoseptal or auricular chondrocytes were enzymatically isolated and amplified in conventional monolayer culture before the cells were seeded into a cell culture insert with a track-etched membrane and cultured in vitro for 3 weeks. The new cartilage formed within the in vitro macroaggregates was analyzed by histology (toluidine blue, von Kossa-safranin O staining), and immunohistochemistry (collagen types I, II, V, VI, and X and elastin). The total glycosaminoglycan (GAG) content of native and engineered auricular as well as nasal cartilage was assayed colorimetrically in a safranin O assay. The biomechanical properties of engineered cartilage were determined by biphasic indentation assay. After 3 weeks of in vitro culture, nasoseptal and auricular chondrocytes synthesized new cartilage with the typical appearance of hyaline nasal cartilage and elastic auricular cartilage. Immunohistochemical staining of cartilage samples showed a characteristic pattern of staining for collagen antibodies that varied in location and intensity. In all samples, intense staining for cartilage-specific collagen types I, II, and X was observed. By the use of von Kossa-safranin O staining a few positive patches-a possible sign of beginning mineralization within the engineered cartilages-were detected. The unique pattern for nasoseptal cartilage is intense staining for type V collagen, whereas auricular cartilage is only weakly positive for collagen types V and VI. Engineered nasal and auricular macroaggregates were negative for anti-elastin antibody (interterritorially). The measurement of total GAG content demonstrated higher GAG content for reformed nasoseptal cartilage compared with elastic auricular cartilage. However, the total GAG content of engineered macroaggregates was lower than that of native cartilage. In spite of the mechanical stability of the auricular macroaggregates, there was no equilibrium of indentation. The histomorphological and immunohistochemical results demonstrate successful cartilage engineering without the use of biomaterials, and identify characteristics unique to hyaline as well as elastic cartilage. The GAG content of engineered cartilage was lower than in native cartilage and the biomechanical properties were not determinable by indentation assay. This study illustrates a novel in vitro macroaggregate culture system as a promising technique for tissue engineering of cartilage grafts. Further long-term in vitro and in vivo studies must be done before this method can be applied to reconstructive surgery of the nose or auricle.

Bone formation after implantation of autolysed antigen extracted allogeneic bone in ovariectomized rabbits

This study was undertaken to evaluate the bone formation response to AAA bone in healthy and oestrogen deficient animals. Seventeen young healthy New Zealand female rabbits were used. Nine rabbits were subjected to ovariectomy and the remaining eight were sham-operated. Four weeks after ovariectomy standardized round cavities, 5mm in diameter, were made medially in the cortical part of each proximal tibia. To half of the cavities autolysed antigen-extracted allogeneic AAA bone granules were added. After another 8 weeks the animals were sacrificed and sections of the tibial experimental areas were obtained. These were studied in light microscopy and the bone and non-bone areas were measured with computer support. The study showed that the addition of a bone inductive substance such as AAA bone enhances bone formation also in oestrogen deficient animals.

Clinical aspects and strategy for biomaterial engineering of an auricle based on three-dimensional stereolithography

At the present time, the partial and/or complete reconstruction of an auricle from autologous rib cartilage is one of most widely published techniques. In the field of tissue engineering, different techniques have been described to generate cartilage tissue using isolated chondrocytes. The basis of these tissue-engineering techniques is bioresorbable or non-bioresorbable biomaterials, which serve as a three-dimensional cell carrier. Tissue engineering of an auricle requires preformed bioresorbable biomaterials designed to fit the form of a patient's auricular defect. Three-dimensional imaging acquired from computed tomography scans or laser surface scanning has become an important tool in modern medicine. This study represents the preoperative procedures for the reconstruction of an auricle through tissue engineering in accordance with the clinical aspects. Hyaff 11, a hyaluronic acid derivative, was used as a three-dimensional cell carrier for isolated human nasoseptal chondrocytes. The chondrocytes were amplified in a conventional monolayer culture before the cells were seeded on a hyaluronic non-woven mesh and cultured in vitro for 4 weeks. The chondrogenic potential of human nasal chondrocytes in Hyaff 11 was investigated by confocal laser scanning microscopy, histology (toluidine blue) and immunohistochemistry (collagen type II). Computer-aided design (CAD) and manufacture of an auricle model with stereolithographical methods were used for the prefabrication of a bioresorbable three-dimensional cell carrier designed in the form of a patient's auricular defect. The cell carrier used was Hyaff 11, a fully benzyl-esterified hyaluronic acid derivative. Confocal laser scanning microscopy has shown good cell attachment, a homogenous distribution of amplified chondrocytes and a viability of more than 90%. After 4 weeks in vitro culture the human nasoseptal chondrocytes synthesized new cartilage with the expression of cartilage-specific collagen type II. In order to shape a patient's designed scaffold the auricle model was fitted exactly and symetrically to the contralateral side. Subsequently, the mirror image patient-specific model was used to prepare an identical scaffold model made of a fully benzyl-esterified hyaluronic acid derivative. The bioresorbable scaffold that was produced gave a satisfactory representation of auricle structure. Bioresorbable preformed biomaterials in the form of a patient's auricle defect represent an important prerequisite for the tissue engineering of autologous auricle grafts. Hyaff 11 seems to be a promising material for tissue engineering of cartilage transplants, and the application of this approach will improve conventional reconstructive surgery in the future.

Effects of Low-Dose Cyclosporin on Osteogenesis of Human Demineralized Bone Grafts in a Surgically Created Mandibular Defect in Rats

BACKGROUND

Demineralized freeze-dried bone matrix (DFDBM) stimulates new bone formation; however, immune reactions from the residual antigens of prepared grafts might play a role in inducing osteogenesis. This study examined whether cyclosporine-A (CsA), an immunosuppressant, enhanced the DFDBM-induced new bone formation.

METHODS

After creating a bony defect in the posterior mandible, 40 male Sprague-Dawley rats were divided into four groups of 10 each: no graft with mineral oil (control); no graft with CsA in mineral oil; DFDBM with mineral oil; and DFDBM with CsA in mineral oil (combined therapy). CsA was administered at 2 mg/kg body weight. Five rats in each group were sacrificed at days 10 and 28 and tissue samples were taken for histological examination.

RESULTS

Soft tissue was observed in the defects of all animals without grafts, whereas the repaired hard tissue formed in the defects of animals with grafts. Histometery, which was performed only at day 10, revealed both DFDBM and CsA therapies produced a significant increase in the total area of repaired hard tissue. Only CsA therapy significantly increased the new bone area. Compared with the DFDBM group, the composition of the repaired hard tissue in the combined therapy group shifted; i.e., the new bone area increased but the residual particle area decreased. The cartilage formation was greater in the combined therapy group than the DFDBM group.

CONCLUSION

Within the limitations of this study, we suggest that the DFDBM grafts play a major role, which could be enhanced by CsA, in the induction of new bone formation, especially at an early phase.

Quantitative and sensitive in vitro assay for osteoinductive activity of demineralized bone matrix

A sensitive, rapid, reliable and quantitative method to check the bone forming potential of demineralized bone matrix (DBM) has been developed. The osteoinductivity of the bone morphogenetic proteins (BMPs), present in DBM, can be measured in vitro using a pluripotent myoblast C2C12 cell line. Alkaline phosphatase activity induced by co-incubation of DBM with C2C12 cells was dose-responsive and corresponds to the amount of active BMPs in DBM. Bone forming potential was simultaneously tested in vivo by implanting DBM intra-muscularly in nude rats. ALP activity induced in C2C12 cells, correlated with bone formation in vivo (r=0.88), determined by alkaline phosphatase activity, mineralization density and histomorphology of the DBM explants. Results from DBM batches, originating from five established Bone Banks, showed good consistency between in vitro and in vivo assays. However, DBM activity varied widely from bank to bank as well as from batch to batch within the same bank.

Effects of enzymatic treatments on the biomechanical properties of screws made of bone

Nowadays, bone tissue employed to manufacture screws used as osteosynthesis material is obtained from organ donors. But in different medical fields there is an increasing need to use xenogenic grafts and implants, which still imply risks of transmission of some diseases and antigenicity. Two different autoclaving programs (A1, A2) and an alternative to reduce the antigenicity of screws made of xenogenic bone based on enzymatic treatment are analyzed from a biomechanical point of view. 128 screws made of bovine femur bone were employed. Some of them were partially demineralized with 0.6 N HCl, enzymatically digested with collagenase (specific) and pepsin (nonspecific) and then autoclaved. The specimens were subjected to tension, shear and screw torque tests and histologically evaluated. Compared to A1, A2 sterilization method (134 degrees C but higher vacuum and longer time) considerably reduced the mechanical strength of specimens. The enzymatic digestion, expected to reduce antigenicity, did not affect the screw superficial structure and would not modify the bone biomechanical properties per se, but maybe because of the association with autoclaving and partial demineralization.

Allogeneic bone grafting of calvarial defects: an experimental study in the rabbit

The purpose of this study was to investigate the incorporation of fresh frozen irradiated membranous allogeneic bone grafts into critical size calvarial defects in the rabbit. Fifteen rabbits had calvarial defects prepared. Twelve rabbits received allogeneic grafts and three received autogenous bone grafts. The rabbits were sacrificed at 9 and 12 months postoperatively, and the specimens were examined radiologically, histopathologically and with fluorescence microscopy. Neovascularization, bone marrow regeneration and new bone formation was evident throughout the grafts however revitalization of the entire graft was incomplete at 12 months. This study revealed that the FFI membranous grafts were well incorporated into rabbit calvarial defects.

O uso da matriz óssea desmineralizada na reparação de lesões osteocondrais: estudo experimental em coelhos

Este estudo teve como finalidade a avaliação do uso de matriz óssea desmineralizada na reparação de lesões osteocondrais. A cartilagem articular tem pequena capacidade regenerativa devido a suas características histológicas e à ausência de vasos sanguíneos. Implantes teciduais e cultura de células condrogênicas foram utilizadas para o tratamento de lesões osteocondrais, porém trazem dificuldades técnicas na fixação e suporte mecânico da região subcondral. A matriz óssea desmineralizada pode facilitar tecnicamente a fixação destes implantes em razão de ser um material firme, porém com características elásticas. Além de ter capacidade osteogênica e produzir osso subcondral, assim funcionando como suporte mecânico, também tem fatores indutores de condrogênese. Lesões osteocondrais foram produzidas em joelhos de 15 coelhos. Os joelhos esquerdos foram tratados com matriz óssea desmineralizada, e os direitos usados como controle comparativo. Realizaram-se avaliações macroscópicas e histológicas nas semanas 02, 04 e 06. Nas lesões tratadas com matriz óssea desmineralizada foi obtido 100% de viabilidade do enxerto e formação de tecido normal de reparação, o qual preencheu a lesão completamente com matriz óssea desmineralizada. A análise histológica demonstrou neoformação óssea e integração do enxerto com o tecido ósseo da região subcondral, e na região superficial da lesão ocorrera a indução de formação de tecido condrogênico. A conclusão deste estudo é que a matriz óssea desmineralizada é útil na reparação de lesões osteocondrais devido a sua capacidade de indução óssea e indução de formação de tecido condrogênico. Pode ser usada no tratamento de lesões osteocondrais como componente de um enxerto composto com tecido condrogênico ou cultura de células condrogênicas. Pode também diminuir as dificuldades técnicas de fixação e suporte estes implantes.

Human bone morphogenetic protein allografting for reconstruction of femoral nonunion

A composite inductive allograft consisting of an allogeneic, autolysed, antigen-free cortical bone carrier lyophilized with partially purified human bone morphogenetic protein was implanted in 30 consecutive femoral reconstructions that resulted from failure of fracture healing. There were 24 atrophic shortened femoral nonunions, four equal length femoral nonunions, and two femoral malunions. There were 10 men and 20 women with an average age of 47 years (range, 28-75 years). Allogeneic, autolysed antigen-free cortical bone was used as a structural alloimplant and as a delivery system for partially purified human bone morphogenetic protein. The composite implant of human bone morphogenetic protein/allogeneic, autolysed antigen-free cortical bone was used in conjunction with one-stage lengthening of the extremity, restoration of mechanical axis and rotational alignment. In 26 of 30 femurs, the human bone morphogenetic protein/allogeneic autolysed antigen-free cortical bone consisted of an allogeneic cortical bone implant incorporated into a one-stage lengthening of atrophic femoral nonunion. In four patients with equal length femoral nonunions, the human bone morphogenetic protein/allogeneic, autolysed antigen-free implant was placed as an medical femoral shaft onlay graft. Internal remodeling of the implant occurred within 8 to 12 weeks after implantation. Lengthening defects greater than 2 cm were supplemented with intercalary autogeneic bone graft. Twenty-four femurs healed at an average of 6 months at an average followup of 55 months. Four of six plate fatigue failures were salvaged with repeat plating. Two patients were lost to followup. The human bone morphogenetic protein/allogeneic, autolysed antigen-free bone allograft is an excellent structural and delivery system that induces host bone formation and implant remodeling allowing salvage of difficult femoral nonunions.

Genetic variability of new bone induction in mice

We studied differences in ectopic osteoinduction in eight mouse inbred strains and an outbred strain. Antigen-extracted autolyzed rat bone gelatin was implanted under hind limb muscle fascia of 12-week-old males, and new bone formation was morphologically assessed on serial sections. Four weeks after implantation, less than half of the implants from CBA/J, A/J, BALB/cJ, and C3Hf/Bu mice showed induction of only cartilage. New cartilage was observed in all, and bone and bone marrow in 80% of the implants from AKR/J, C57BL/6J, DBA/2J, and RFM/Rij mice. Volume of the newly formed tissue ranged from 1.3% of the old matrix in A/J strain to 74.6% in DBA/2J strain. Outbred CD1 mice showed only weak cartilage induction. The "good" responders differed among themselves in the volume and type of newly induced tissue: DBA/2J, RFM/Rij, and AKR/J mice had a similar ratio of new bone and cartilage and abundant bone marrow, whereas the predominant newly induced tissue in C57Bl/6J mice was cartilage. The pattern of the expression of BMP-2, -4, and -7, alkaline phosphatase, osteocalcin, interferon-gamma, and granulocyte-macrophage colony-stimulating factor, measured by reverse transcriptase polymerase chain reaction, did not correlate with the type and the quantity of the newly induced tissue. Our results show that adult mice of inbred strains differ not only in the peak bone mass and morphology, but also ability to form new bone after an osteoinductive stimulus. Ectopic osteoinduction may be a useful in vivo model to investigate genetic determinants of endochondral osteogenesis, especially its immunological component.

Bone bonding in bioactive glass ceramics combined with bone matrix gelatin

To determine how to encourage inductive osteogenesis on bioactive ceramics and accelerate the bonding of implants to the surrounding bone, we studied the role of autolyzed antigen-extracted allogeneic bone gelatin (AAAG) in bone bonding to bioactive ceramic implants in rabbit tibiae. Smooth-surfaced plates (15 x 10 x 2 mm) of apatite and wollastonite containing glass-ceramic were implanted into the proximal metaphyses of tibiae, with AAAG packed into the medullary cavity in one limb but not in the contralateral limb, which served as a paired control. After 2, 4, 8, 16, and 25 weeks, bone bonding and bone formation at the bone/implant interfaces were evaluated by a detaching test and undecalcified histological examination. The tensile failure load increased from 2 to 25 weeks for both groups. The failure load of the AAAG-treated group was significantly greater than that of the control group at every stage. Histologically, the AAAG-treated specimens showed active new bone formation in the medullary cavity and extensive bonding between the implant and bone at early periods. The percentage of bony covering in the AAAG-treated group was significantly higher than that of the controls at all intervals except at 25 weeks. The results of this study suggest that the addition of osteoinductive AAAG to a bioactive implant may significantly accelerate bone apposition to the implant and improve the bonding process at the interface, which would help to establish an earlier and stronger bonding between the implants and the surrounding bone.

Bone bonding in bioactive glass ceramics combined with bone matrix gelatin

To determine how to encourage inductive osteogenesis on bioactive ceramics and accelerate the bonding of implants to the surrounding bone, we studied the role of autolyzed antigen-extracted allogeneic bone gelatin (AAAG) in bone bonding to bioactive ceramic implants in rabbit tibiae. Smooth-surfaced plates (15 x 10 x 2 mm) of apatite and wollastonite containing glass-ceramic were implanted into the proximal metaphyses of tibiae, with AAAG packed into the medullary cavity in one limb but not in the contralateral limb, which served as a paired control. After 2, 4, 8, 16, and 25 weeks, bone bonding and bone formation at the bone/implant interfaces were evaluated by a detaching test and undecalcified histological examination. The tensile failure load increased from 2 to 25 weeks for both groups. The failure load of the AAAG-treated group was significantly greater than that of the control group at every stage. Histologically, the AAAG-treated specimens showed active new bone formation in the medullary cavity and extensive bonding between the implant and bone at early periods. The percentage of bony covering in the AAAG-treated group was significantly higher than that of the controls at all intervals except at 25 weeks. The results of this study suggest that the addition of osteoinductive AAAG to a bioactive implant may significantly accelerate bone apposition to the implant and improve the bonding process at the interface, which would help to establish an earlier and stronger bonding between the implants and the surrounding bone.

Long-term maintenance of alveolar bone gain after implantation of autolyzed, antigen-extracted, allogenic bone in periodontal intraosseous defects

This randomized controlled trial assessed the long-term maintenance of alveolar bone gain after implantation of autolyzed, antigen-extracted, allogenic (AAA) bone. AAA bone is a demineralized freeze-dried bone allograft processed after previously described methods. In each of 14 patients, AAA bone was implanted into the intraosseous defect of 1 tooth (test); a second tooth with an intraosseous defect was treated by modified Widman flap surgery alone (control). All patients were offered supportive periodontal therapy at 3- to 6-month intervals following treatment. Clinical measurements were taken prior to surgery, 6 months, and 3 years following surgery. Of the 14 patients enrolled, 11 patients completed the 6-month and 8 patients the 3-year examination. In test teeth, bone gain was significantly greater compared to control teeth at 6 months (2.2+/-0.5 mm and 1.2+/-0.5 mm, respectively) and 3 years (2.3+/-0.7 mm and 1.1+/-0.8 mm, respectively) (P < 0.05). Also, more probing attachment was gained in test compared to control teeth at 3 years (2.0+/-0.7 mm and 0.8+/-0.5 mm, respectively; P < 0.05). At 3 years, Porphyromonas gingivalis was detected in 3 test and 2 control teeth by polymerase chain reaction, whereas no Actinobacillus actinomycetemcomitans was found. Due to the low detection frequency, there was no clear correlation between the maintenance of alveolar bone during supportive periodontal therapy and subgingival infection with P. gingivalis. The data indicated that alveolar bone gain after implantation of AAA bone may be maintained over a minimum of 3 years in patients receiving periodontal supportive therapy.

[Osteoinduction and -reparation]

Traumata, diseases, developmental deformities, and tumor resections frequently cause bone defects and atrophies. In general, three different mechanisms exist by which bone restoration can be achieved: (1) osteogenesis initiated by vital, osteoblastic cells of autografts; (2) osteoconduction (or creeping substitution); and (3) osteoinduction. The latter mechanism means the differentiation of pluripotent, mesenchymal-type cells (located in a recipient bed with strong regenerative capacity) into cartilage- and bone-forming progenitor cells under the influence of inductive bone morphogenetic proteins (BMPs). Some BMPs are physiologically included in low concentrations as organic components in bone tissue. They can diffuse from demineralized bone implants into the recipient bed and induce a differentiation into new bone tissue. Nine different BMPs have been isolated, characterized, and cloned. Some of these possess inductive properties and can initiate new bone formation in muscle tissue or in bone defects. In the future recombinant BMPs will be available in unlimited quantities. This will lead to completely new therapeutic concepts in reconstructive bone surgery.

Periodontal regeneration around natural teeth

1. Evidence is conclusive (Table 2) that periodontal regeneration in humans is possible following the use of bone grafts, guided tissue regeneration procedures, both without and in combination with bone grafts, and root demineralization procedures. 2. Clinically guided tissue regeneration procedures have demonstrated significant positive clinical change beyond that achieved with debridement alone in treating mandibular and maxillary (buccal only) Class II furcations. Similar data exist for intraosseous defects. Evidence suggests that the use of bone grafts or GTR procedures produce equal clinical benefit in treating intraosseous defects. Further research is necessary to evaluate GTR procedures compared to, or combined with, bone grafts in treating intraosseous defects. 3. Although there are some data suggesting hopeful results in Class II furcations, the clinical advantage of procedures combining present regenerative techniques remains to be demonstrated. Additional randomized controlled trials with sufficient power are needed to demonstrate the potential usefulness of these techniques. 4. Outcomes following regenerative attempts remain somewhat variable with differences in results between studies and individual subjects. Some of this variability is likely patient related in terms of compliance with plaque control and maintenance procedures, as well as personal habits; e.g., smoking. Variations in the defects selected for study may also affect predictability of outcomes along with other factors. 5. There is evidence to suggest that present regenerative techniques lead to significant amounts of regeneration at localized sites on specific teeth. However, if complete regeneration is to become a reality, additional stimuli to enhance the regenerative process are likely needed. Perhaps this will be accomplished in the future, with combined procedures that include appropriate polypeptide growth factors or tissue factors to provide additional stimulus.

Repair of human skull defects using osteoinductive bone alloimplants

To estimate the efficacy of cranioplasty in clinical practice, autolyzed, antigen-extracted, allogenic (AAA) bone was prepared from cortical bones of human organ donors. AAA bone implants consisted of completely demineralized bone powder, completely demineralized pliable bone chips, surface-demineralized bone chips with pliable crevices, surface-demineralized rigid bone chips, or combinations thereof. 21 patients received AAA bone cranioplasties and were followed-up for between 12 and 58 months (average: 29 months). No infection or rejection of any of the AAA bone implants occurred. X-ray assessments as well as bone scintigraphies revealed osseous integration and remodelling of the AAA bone implants with minimal resorption, with the exception of completely demineralized AAA bone chips which showed partial resorption (2 cases). However, the partial resorption of completely demineralized AAA bone chips ceased after the implants had been remodelled. In 4 cases, the osteosynthesis material was removed between 10 and 18 months after the cranioplasty. In another case, a re-entry was necessary because of recurrence of an intracranial tumor. All of these five AAA bone reconstructions showed bleeding surfaces and osseous consolidations at the time of re-entry. A bone biopsy taken from one of these cranioplasties showed osteoinduction on the surface of the AAA bone implants. This first clinical review of cranial reconstructions using osteoinductive AAA bone implants emphasizes the therapeutical application of AAA bone for cranioplasty. Large AAA bone chips from human skull bones facilitate the reproduction of the skull's convexity especially when combined with preoperative stereolithography-based planning.

Does xenogeneic demineralized bone matrix have clinical utility as a bone graft substitute?

Autologous bone harvested from the iliac crest is a commonly used grafting material for a number of surgical procedures; however, there is documented morbidity associated with secondary site harvesting. Because demineralized bone matrix (DBM) is inherently osteoinductive (i.e., it facilitates differentiation of uncommitted connective tissue cells into bone-forming cells), it has potential appeal as a bone-graft substitute. Allogeneic DBM usage has intrinsic shortcomings related to procuring, processing and characterizing bone from a human donor pool. Xenogeneic bone represents an unlimited supply of available material if it can be processed to render it safe for transplantation to the human host. It is hypothesized that reported immunogenicity and non-viability of xenogeneic DBM results from lipids and plasma proteins not removed during typical demineralization processes. The authors propose a rigorous examination of this hypothesis, followed by several pivotal studies to determine the effectiveness of xenogeneic DBM.

Stereolithography in oral and maxillofacial operation planning

Stereolithography (STL) is a method of organ-model-production based on computed tomography scans which enables the representation of complex 3-dimensional anatomical structures. Surfaces and internal structures of organs can be produced by polymerization of UV-sensitive liquid resin using a laserbeam. In oral and maxillofacial surgery this technique is advantageous for reconstruction of severe skull defects because a more accurate preoperative planning is possible. Using recently developed software we are able to reconstruct unilateral bony defects by virtual mirror imaging of the contralateral side and production of a STL mirror model as well as the reconstruction of non-mirrorable defects by superposition. Advantages of STL are the representation of complex anatomical structures, high precision and accuracy, and the option to sterilize the models for intraoperative use. More accurate planning using this method improves postoperative results, decreases risks and shortens treatment time.