Tricalcium Phosphate Granules Research Articles

Preliminary study of bone repair in a non-critical defect after the implantation of wollastonite and tricalcium phosphate granules

Introdução: a bioengenharia tecidual é uma área multidisciplinar que busca desenvolver novas técnicas e biomateriais que substituam o tecido ósseo lesionado ou estimulem a regeneração óssea. Os biomateriais cerâmicos constituem uma alternativa promissora devido à biocompatibilidade, osteocondutividade, bioatividade e biorreabsorção. Nesse contexto, a associação das cerâmicas wollastonita e fosfato tricálcico resulta em um biomaterial compósito com propriedades osteogênicas superiores em relação a seus constituintes, quando utilizados de forma isolada. O objetivo deste estudo foi avaliar histomorfologicamente a fase inicial do reparo de defeito ósseo não crítico após a implantação de grânulos de wollastonita (W) e β-fosfato tricálcico (β-TCP), em diferentes proporções. Metodologia: dezoito animais foram aleatoriamente distribuídos em três grupos experimentais, compostos por seis animais em cada: i) W60 – grupo com grânulos de 60 % de W e 40% de β-TCP, em defeito ósseo não crítico; ii) T20 – grupo com grânulos de 80% de W e 20% de β-TCP, em defeito ósseo não crítico; III) GC – grupo de controle, sem implantação de biomateriais no defeito ósseo não crítico. E foram avaliados após 15 dias de pós-operatório. Resultados: a análise histológica evidenciou, aos 15 dias, discreta neoformação óssea reparativa, restrita às bordas, inflamação crônica granulomatosa moderada, com escassas células gigantes multinucleadas, preenchimento do defeito com grânulos por toda a extensão e formação de tecido conjuntivo frouxo de permeio aos biomateriais. Conclusão: os compósitos de W/β-TCP avaliados neste estudo, no ponto biológico de 15 dias, foram biocompatíveis, osteocondutores e bioativos, o que indica elevado potencial para uso como substitutos ósseos.

Erratum to ‘Thermal treatment at 500°C significantly reduces the reaction to irregular tricalcium phosphate granules as foreign bodies: An in vivo study’ [Acta Biomaterialia, 121 (2021) 621-636

Erratum to ‘Thermal treatment at 500°C significantly reduces the reaction to irregular tricalcium phosphate granules as foreign bodies: An in vivo study’ [Acta Biomaterialia, 121 (2021) 621-636

Does harvesting cancellous bone destabilize cervical spine in cervical interbody fusion? A prospective clinicoradiological analysis

Background: To analyse the effect of graft harvesting from adjacent vertebral bodies in Anterior Cervical Discectomy and Fusion.Objective: The objective of this study is to analyze the effect of harvesting bone graft from adjacent vertebral bodies on cervical spine stability, vertebral segment height, and cervical lordosis in single-level anterior cervical discectomy and fusion (ACDF).Material and Methods: Thirty patients suffering from cervical radiculopathy and myelopathy were operated on using adjacent corticocancellous bone graft (ACBG) technique. In this technique, autologous cancellous bone is harvested from adjacent vertebral bodies and packed in the intervertebral body cage and the cavities in vertebral bodies are filled with tricalcium phosphate granules. Radiological studies with X-rays of the cervical spine were taken in lateral views preoperatively, immediate postoperatively, and during follow-up periods at intervals of 3-month duration, namely 3, 6, 9, 12 months, and at the end of 2 years postoperatively. Studies undertaken were – degree of fusion using modified Bridewell's formula, disc space settlement using Indigenous method, and vertebral segment height and lordotic angle using Cobb's angle.Results: Satisfactory bony fusion was seen achieved in all patients at the end of 1 year. Although the settlement of disc space was appreciated, vertebral segment height remained increased at the end of 1 year. Cervical lordosis increased over a period of time during fusion process. The average preoperative Cobb's angle of 15.61° ± 1.81° improved to 20° ± 1.37°degrees at the end of 2 years postoperatively.Conclusion: Harvesting bone from adjacent cervical vertebrae does not weaken spinal segment and the fear and skepticism that prevailed over the years are false. ACBG technique is a potential alternative to other existing techniques in ACDF.

Fabrication and Evaluation of Layered Double Hydroxide-Enriched ß-Tricalcium Phosphate Nanocomposite Granules for Bone Regeneration: In Vitro Study.

One of the most important challenges facing tissue engineering researches is the scaffold design with optimum physical and mechanical properties for growth and proliferation of cells, and tissue formation. The aim of this study was to produce a novel nanocomposite containing β-tricalcium phosphate and layered double hydroxide (β-TCP-LDH) and analyzing the capacity of its osteogenic activity in vitro. In this paper, β-tricalcium phosphate and layered double hydroxide powders were synthesized by co-precipitation processes. Then, the porous nanocomposite granules were prepared by the polyurethane sponge replication method. In this study, four kinds of β-TCP granules containing LDHs nanoparticles (ranging from 0.1 to 10wt%) have been prepared. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) analyses were selected to study the phase structure, morphology, and phase distribution, respectively. Physicochemical characterizations demonstrated that the granules were synthesized successfully. Interconnected macro pores ranging over 200-500μm were observed for all kinds of granules. SEM micrographs showed that human mesenchymal stem cells (hMSCs) were attached to the surfaces of the granules and proliferated in good shape. The results warranted that the synthesized granules exhibited good biocompatibility and mineralization. Based on the results of compressive strength and porosity tests, the most suitable type of granule is β-TCP/LDH 10wt% with 77% porosity and compressive modulus of 231.4MPa, which can be utilized in bone tissue engineering. To our knowledge, layered double hydroxides have not previously been incorporated into tricalcium phosphate granules for bone grafting. Also, this study is the first report on the effects of LDH on the mechanical properties and porosity of β-TCP granules. Our results demonstrated that β-TCP/LDH nanocomposite granule has a great potential for bone defects regeneration and tissue engineering applications.

Thermal treatment at 500 °C significantly reduces the reaction to irregular tricalcium phosphate granules as foreign bodies: An in vivo study

Evaporation of phosphate species during thermal treatment (> 400 °C) of calcium phosphates leads to the formation of an alkaline layer on their surface. The aim of this study was to evaluate the hypothesis that the biological response of thermally treated calcium phosphates is modified by the presence of such an alkaline layer on their surface. For this purpose, 0.125–0.180 mm α- and β-tricalcium phosphate (TCP) granules were obtained by crushing and size classification, with some being subjected to thermal treatment at 500 °C. The four types of granules (α-TCP, β-TCP, α-TCP-500 °C, and β-TCP-500 °C) were implanted subcutaneously and orthotopically in rats. Sham operations served as control.Subcutaneously, α-TCP and β-TCP induced significantly more multinucleated giant cells (MNGCs) than calcined granules. Most of the induced MNGCs were TRAP-negative, CD-68 positive and cathepsin K-negative, reflecting a typical indication of a reaction with a foreign body. The vessel density was significantly higher in the α-TCP and β-TCP groups than it was in the α-TCP-500 °C and β-TCP-500 °C groups. In the femur model, β-TCP-500 °C induced significantly more new bone formation than that induced by β-TCP. The granule size was also significantly larger in the β-TCP-500 °C group, making it more resistant to degradation than β-TCP. The MNGC density was higher in the α-TCP and β-TCP groups than in the α-TCP-500 °C and β-TCP-500 °C groups, including cathepsin-positive, CD-68 positive, TRAP-positive and TRAP-negative MNGCs.In conclusion, this study confirms that the biological response of calcium phosphates was affected by the presence of an alkaline layer on their surface. Thermally-treated α-TCP and β-TCP granules produced significantly fewer MNGCs and were significantly less degraded than non-thermally-treated α-TCP and β-TCP granules. Thermally treating α-TCP and β-TCP granules shifts the reaction from a foreign body reaction towards a physiological reaction by downregulating the number of induced MNGCs and enhancing degradation resistance.

Notch Signaling Inhibition by LY411575 Attenuates Osteoblast Differentiation and Decreased Ectopic Bone Formation Capacity of Human Skeletal (Mesenchymal) Stem Cells.

Background Chemical biology approaches using small molecule inhibitors targeting specific signaling pathways are useful tools to dissect the molecular mechanisms governing stem cell differentiation and for their possible use in therapeutic interventions. Methods Stem cell signaling small molecule library functional screen was performed employing human bone marrow skeletal (mesenchymal) stem cells (hBMSCs). Alkaline phosphatase (ALP) activity and formation of mineralized matrix visualized by Alizarin red staining were employed as markers for osteoblastic differentiation. Global gene expression profiling was conducted using the Agilent microarray platform, and data normalization and bioinformatics were performed using GeneSpring software. Pathway analyses were conducted using the Ingenuity Pathway Analysis (IPA) tool. In vivo ectopic bone formation was performed using hBMSC mixed with hydroxyapatite–tricalcium phosphate granules that were implanted subcutaneously in 8-week-old female nude mice. Hematoxylin and eosin staining and Sirius red staining were performed to identify bone formation in vivo. Results Among the tested molecules, LY411575, a potent γ-secretase and Notch signaling inhibitor, exhibited significant inhibitory effects on osteoblastic differentiation of hBMSCs manifested by reduced ALP activity, mineralized matrix formation, and decreased osteoblast-specific gene expression as well as in vivo ectopic bone formation. Global gene expression profiling of LY411575-treated cells revealed changes in multiple signaling pathways, including focal adhesion, insulin, TGFβ, IL6, and Notch signaling, and decreased the expression of genes associated with functional categories of tissue development. Among the affected signaling networks were TGFβ1, SPP1, and ERK regulatory networks. Conclusions We identified γ-secretase inhibitor (LY411575) as a potent regulator of osteoblastic differentiation of hBMSC that may be useful as a therapeutic option for treating conditions associated with ectopic bone formation.

Stem cell library screen identified ruxolitinib as regulator of osteoblastic differentiation of human skeletal stem cells

BackgroundBetter understanding of the signaling pathways that regulate human bone marrow stromal stem cell (hBMSC) differentiation into bone-forming osteoblasts is crucial for their clinical use in regenerative medicine. Chemical biology approaches using small molecules targeting specific signaling pathways are increasingly employed to manipulate stem cell differentiation fate.MethodsWe employed alkaline phosphatase activity and staining assays to assess osteoblast differentiation and Alizarin R staining to assess mineralized matrix formation of cultured hBMSCs. Changes in gene expression were assessed using an Agilent microarray platform, and data normalization and bioinformatics were performed using GeneSpring software. For in vivo ectopic bone formation experiments, hMSCs were mixed with hydroxyapatite–tricalcium phosphate granules and implanted subcutaneously into the dorsal surface of 8-week-old female nude mice. Hematoxylin and eosin staining and Sirius Red staining were used to detect bone formation in vivo.ResultsWe identified several compounds which inhibited osteoblastic differentiation of hMSCs. In particular, we identified ruxolitinib (INCB018424) (3 μM), an inhibitor of JAK-STAT signaling that inhibited osteoblastic differentiation and matrix mineralization of hMSCs in vitro and reduced ectopic bone formation in vivo. Global gene expression profiling of ruxolitinib-treated cells identified 847 upregulated and 822 downregulated mRNA transcripts, compared to vehicle-treated control cells. Bioinformatic analysis revealed differential regulation of multiple genetic pathways, including TGFβ and insulin signaling, endochondral ossification, and focal adhesion.ConclusionsWe identified ruxolitinib as an important regulator of osteoblast differentiation of hMSCs. It is plausible that inhibition of osteoblast differentiation by ruxolitinib may represent a novel therapeutic strategy for the treatment of pathological conditions caused by accelerated osteoblast differentiation and mineralization.

Treatment of the benign lytic lesions of the proximal femur with synthetic bone graft

BackgroundBenign bone tumors and tumor-like conditions are commonly located in the proximal femur. The main indications for surgical treatment are lesions with impending or actual pathological fractures, or with aggressive or recurrent lesions. However, patients complaining of persistent pain, limping, or abnormal gait patterns are also considered for surgical treatment. In this study, we describe the outcomes of the surgical treatment of benign lytic lesions of the proximal femur by curettage followed by implantation of synthetic bone graft.MethodsThis retrospective study included 27 patients (22 females and 5 males) with benign lytic lesions of the proximal femur. The average age was 25.5 years (6–65 years), and the mean follow-up period was 54.5 months (9–145 months). The histopathological diagnoses were fibrous dysplasia (8 patients), simple bone cyst (8 patients), chondroblastoma (7 patients), giant cell tumor (3 patients), and eosinophilic granuloma (1 patient). These lesions were managed with curettage followed by implantation of the bone defects with alpha tricalcium phosphate in 14 patients, beta tricalcium phosphate granules in 11 patients, hydroxyapatite granules in 1 patient, and combined beta tricalcium phosphate and hydroxyapatite granules in 1 patient. Internal fixation was performed in three patients.ResultsThe mean operative time was 143 min (80–245 min). Patients had regained normal unrestricted activity without pain at the operation site. Patients treated with beta tricalcium phosphate achieved radiographic consolidation of the bone defects within 1 year after the surgery, and those treated with alpha tricalcium phosphate or hydroxyapatite experienced no progression nor recurrence of the lesions. Local tumor recurrence was observed in one patient with giant cell tumor 5 years after the surgery. Post-operative pathological fracture was occurred in one patient with a simple bone cyst of the subtrochanteric region 1 month after surgery. No post-operative infection was observed.ConclusionWe concluded that the treatment of benign lytic lesions of the proximal femur, either primary or recurrent, using synthetic bone graft is a safe and satisfactory method and the addition of internal fixation should be carefully planned.

Human Bone Marrow Mesenchymal Stromal Cells Promote Bone Regeneration in a Xenogeneic Rabbit Model: A Preclinical Study.

Significant research efforts have been undertaken during the last decades to treat musculoskeletal disorders and improve patient's mobility and quality of life. The goal is the return of function as quickly and completely as possible. Cellular therapy has been increasingly employed in this setting. The design of this study was focused on cell-based alternatives. The present study aimed at investigating the bone regeneration capacity of xenogeneic human bone marrow-derived mesenchymal stromal cell (hMSC) implantation with tricalcium phosphate (TCP) granules in an immunocompetent rabbit model of critical-size bone defects at the femoral condyles. Two experimental groups, TCP and hMSC + TCP, were compared. Combination of TCP and hMSC did not affect cell viability or osteogenic differentiation. We also observed significantly higher bone regeneration in vivo in the hMSC + TCP group, which also displayed better TCP osteointegration. Also, evidence of hMSC contribution to a better TCP osteointegration was noticed. Finally, no inflammatory reaction was detected, besides the xenotransplantation of human cells into an immunocompetent recipient. In summary, hMSC combined with TCP granules is a potential combination for bone regeneration purposes that provides better preclinical results compared to TCP alone.

The Microctructure Formation and the Composite Properties Based on Alginate with Antibacterial Activity

The alginate gels microstructure formation regularities that were prepared in situ in a multicomponent system were determined, and their properties were studied. To produce experimental specimens, a combination of cross-linking agents of calcium and zinc salts with inhibitors based on a denatured protein and tricalciumphosphate granules was used. The antibacterial properties of the hydrogels were studied as a function of their composition.

Composite hydrogels based on alginate-reinforced calcium phosphate ceramics for tissue engineering

Composite hydrogels in the system of sodium alginate–tricalcium phosphate (TCP) are studied. The gelation time, mechanical properties, and solubility of composite hydrogels are investigated in relation to the content of a reinforcing component such as TCP granules introduced in an amount of 10, 20, and 30 wt %.

Repair of segmental radial defects in dogs using tailor-made titanium mesh cages with plates combined with calcium phosphate granules and basic fibroblast growth factor-binding ion complex gel.

Repair of large segmental defects of long bones are a tremendous challenge that calls for a novel approach to supporting immediate weight bearing and bone regeneration. This study investigated the functional and biological characteristics of a combination of a tailor-made titanium mesh cage with a plate (tTMCP) with tetrapod-shaped alpha tricalcium phosphate granules (TB) and basic fibroblast growth factor (bFGF)-binding ion complex gel (f-IC gel) to repair 20-mm segmental radial defects in dogs. The defects were created surgically in 18 adult beagle dogs and treated by implantation of tTMCPs with TB with (TB-gel group) or without (TB group) f-IC gel. Each tTMCP fitted the defect well, and all dogs could bear weight on the affected limb immediately after surgery. Dogs were euthanized 4, 8 and 24weeks after implantation. Histomorphometry showed greater infiltration of new vessels and higher bone union rate in the TB-gel group than in the TB group. The lamellar bone volume and mineral apposition rate did not differ significantly between the groups, indicating that neovascularization may be the primary effect of f-IC gel on bone regeneration. This combination method which is tTMCP combined with TB and f-IC gel, would be useful for the treatment of segmental long bone defects.

Micro-CT Analysis of Bone Healing in Rabbit Calvarial Critical-Sized Defects with Solid Bioactive Glass, Tricalcium Phosphate Granules or Autogenous Bone.

ABSTRACTObjectivesThe purpose of the present study was to evaluate bone healing in rabbit critical-sized calvarial defects using two different synthetic scaffold materials, solid biodegradable bioactive glass and tricalcium phosphate granules alongside solid and particulated autogenous bone grafts.Material and MethodsBilateral full thickness critical-sized calvarial defects were created in 15 New Zealand white adult male rabbits. Ten defects were filled with solid scaffolds made of bioactive glass or with porous tricalcium phosphate granules. The healing of the biomaterial-filled defects was compared at the 6 week time point to the healing of autologous bone grafted defects filled with a solid cranial bone block in 5 defects and with particulated bone combined with fibrin glue in 10 defects. In 5 animals one defect was left unfilled as a negative control. Micro-computed tomography (micro-CT) was used to analyze healing of the defects.ResultsMicro-CT analysis revealed that defects filled with tricalcium phosphate granules showed new bone formation in the order of 3.89 (SD 1.17)% whereas defects treated with solid bioactive glass scaffolds showed 0.21 (SD 0.16)%, new bone formation. In the empty negative control defects there was an average new bone formation of 21.8 (SD 23.7)%.ConclusionsAccording to findings in this study, tricalcium phosphate granules have osteogenic potential superior to bioactive glass, though both particulated bone with fibrin glue and solid bone block were superior defect filling materials.

Bone healing in rabbit calvarial critical-sized defects filled with stem cells and growth factors combined with granular or solid scaffolds.

In pediatric neurosurgery, decompressive craniectomy and correction of congenital cranial anomalies can result in major cranial defects. Corrective cranioplasty for the repair of these critical-sized defects is not only a cosmetic issue. The limited availability of suitable autogenous bone and the morbidity of donor site harvesting have driven the search for new approaches with biodegradable and bioactive materials. This study aimed to assess the healing of rabbit calvarial critical-sized defects filled with osteogenic material, either with bioactive glass scaffolds or tricalcium phosphate granules in various combinations with adipose stem cells or bone marrow stem cells, BMP-2, BMP-7, or VEGF to enhance osteogenesis. Eighty-two bicortical full thickness critical-sized calvarial defects were operated. Five defects were left empty as negative control defects. The remaining 77 defects were filled with solid bioactive glass scaffolds or tricalcium phosphate granules seeded with adipose or bone marrow derived stem cells in combination with BMP-2, BMP-7, or VEGF. The defects were allowed to heal for 6 weeks before histologic and micro-CT analyses. Micro-CT examination at the 6-week post-operative time point revealed that defects filled with stem cell-seeded tricalcium phosphate granules resulted in new bone formation of 6.0 %, whereas defects with bioactive glass scaffolds with stem cells showed new bone formation of 0.5 to 1.7 %, depending on the growth factor used. This study suggests that tricalcium phosphate granules combined with stem cells have osteogenic potential superior to solid bioactive glass scaffolds with stem cells and growth factors.

Iron-labeled adipose stem cells and neovascularization in rabbit calvarial critical-sized defects

The aim of this study was to evaluate the presence of iron-labeled adipose stem cells at the 2-week time point and vascular changes at the 2-week and 6-week time points using two different types of scaffolds. This study included 22 White New Zealand adult male rabbits. In six rabbits, full-thickness calvarial critical-sized defects were filled with autogenous adipose stem cells labeled with iron oxide seeded onto two scaffolds, namely, solid bioactive glass (BAG) or porous tricalcium phosphate granules (TCP) used on reciprocal sides of the skull. Eleven rabbits were implanted with adipose stem cell-seeded scaffolds without iron labeling for analysis of vascular changes. Five defects were left empty as negative control defects. The specimens were analyzed histologically at the 2-week and 6-week time points. The TCP group showed significantly more vascularity compared with the BAG group. A greater number of labeled stem cells were identified in the TCP group compared with the BAG group, but the difference was not statistically significant. This study revealed the differences in stem cell distribution and revascularization of the calvarial defect, which may be biomaterial dependent.

Strengthening of deformable bone cements in the calcium phosphates–chitosan system by tricalcium phosphate granules

The possibility of strengthening chitosan-containing calcium phosphate bone cements sintered with tricalcium phosphate granules was studied. The strength was found to depend on the granules content in a nonmonotonic manner. For materials reinforced with 300–500 µm granules in the amount of 20 wt %, the compression strength of about 15 MPa was reached on day 14 of air hardening, which was 50% higher than that of the unreinforced cement matrix. The main crystalline phase of the cement matrix is amorphous calcium phosphate. Dissolution of cement in isotonic saline corresponds to first-order reaction kinetics.

Effect of a rapidly resorbable calcium alkali phosphate bone grafting material on bone formation and osteogenic marker expression after sinus floor augmentation in humans

Event Abstract Back to Event Effect of a rapidly resorbable calcium alkali phosphate bone grafting material on bone formation and osteogenic marker expression after sinus floor augmentation in humans Christine Knabe-Ducheyne1*, Tom Knauf1*, Barbara Peleska2*, Georg Berger3*, Renate Gildenhaar3, Cynthia Wirth3*, Alexander Rack4, Wolf-Dietrich Huebner5 and Michael Stiller1 1 Philipps-University Marburg, Dept. of Experimental Orofacial Medicine, Germany 2 Philipps University Marburg, Department of Prosthodontics, Germany 3 Federal Institute for Materials Research and Testing, Division “Ceramic processing and biomaterials”, Germany 4 European Synchrotron Radiation Facility, Structure of Materials Group, France 5 Curasan AG, Division of Clinical Studies, Germany Introduction: Sinus floor augmentation (SFA) has become a well-established pre-implantology procedure for alveolar ridge augmentation of the posterior maxilla[1]. Using synthetic biodegradable bone substitutes avoids second-site surgery for autograft harvesting[1]. Compared to the bone substitutes which are currently clinically available, there is a significant need for bone substitutes which degrade more rapidly, but still stimulate osteogenesis at the same time. This has led to the development of bioactive, rapidly resorbable calcium alkali orthophosphate (CAP) materials[1]. Previously, we were able to show that a silica containing CAP GB9 (Si-CAP) had a greater stimulatory effect on osteoblast differentiation and bone formation in vitro and in vivo after alveolar ridge augmentation in a sheep, when compared to the clinically established materials tricalcium phosphate (TCP) and bioactive glass 45S5[1]. This effect was associated with simultaneous enhanced activation of the ERK differentiation, the PI3K cell survival as well as of the alternate p38 pathways[2], and was in addition to exhibiting a greater biodegradability. In the current study, the biodegradability and effect of this Si-CAP on osteogenesis was evaluated in biopsies sampled 6 months after SFA and compared to that of TCP. Methods: The study consisted of 38 patients (22 women,16 men) ranging in age from 54-69 years. In all patients SFA was required in order to facilitate dental implant placement. Test materials were: first, granules with a crystalline phase Ca2KNa(PO4)2 and with a small amorphous portion containing sodium magnesium silicate (Si-CAP) (porosity 75%, grain size 1000 to 2000 µm; Osseolive™,Curasan AG, Germany). Second, ß-TCP granules (porosity 65%, grain size 700 to 1400 µm, Ceros™; Mathys Inc., Switzerland). SFA was performed using a combination (10:1 ratio) of Si-CAP or TCP granules and autogenous bone chips. At implant surgery, 6 months after SFA, when preparing the implant bed, cylindrical biopsies, 2.5 mm in diameter and 10 mm long, were sampled using a trephine drill. The samples were processed utilizing a technique which facilitated performing immunohistochemical analysis on hard tissue sections[3],[4] using primary antibodies specific to collagen type I (Col I), alkaline phosphatase (ALP), osteocalcin (OC) and bone sialoprotein (BSP). First, histomorphometric evaluation of the sections was performed. To this end, a rectangular area 2 mm2 in size was defined in each section at a distance of 3 mm from the native alveolar crest, i.e. centrally, as well as apically just underneath the Schneiderian membrane. The bone area fraction, the graft material area fraction and the bone-biomaterial-contact were measured in both areas using a light microscope in combination with a digital camera (DP73) and Cellsens software (Olympus, Germany).[3][4] Second, semi-quantitative analysis of the immunohistochemical staining was performed. A scoring system quantified the amount of staining observed using light microscopy. A score of (+++), (++) and (+) corresponded to strong, moderate or mild, whereas a score of (0) correlated with no staining[4],[5]. Results: Both materials facilitated bone formation and matrix mineralization, which were still actively progressing from the sinus floor in an apical direction 6 months after SFA. Bone formation, the bone-biomaterial-contact, i.e. bone-bonding, and particle degradation were greater, i.e. more advanced, with the Si-CAP grafting material compared to TCP, both in the apical (Fig. 1) as well as in the central region. This was accompanied by greater expression of Col I, BSP and OC in the newly formed bone tissue in the Si-CAP samples compared to TCP. Fig. 1. Bone area fraction, particle area fraction and bone-biomaterial- contact in the apical region of biopsies sampled 6 months after SFA. Discussion and Conclusions: Six months after implantation Si-CPA facilitated greater bone formation and biodegradability than the TCP graft material, whose excellent osteoconductive properties have been widely documented[1],[4],[5]. Consequently, Si-CAP can be regarded as excellent grafting material for SFA in a clinical setting. The authors would like to thank Ms. A. Kopp for her excellent technical assistance.

Comparison of the Bone Forming Ability of Different Sized-alpha Tricalcium Phosphate Granules using a Critical Size Defect Model of the Mouse Calvaria

Comparison of the Bone Forming Ability of Different Sized-alpha Tricalcium Phosphate Granules using a Critical Size Defect Model of the Mouse Calvaria

<i>In Vivo</i> Osteogenesis Assessment of a Tricalcium Phosphate Paste and a Tricalcium Phosphate Foam Bone Grafting Materials

Calcium phosphates (CaPs) are synthetic bone grafting materials. CaPs are an alternative to overcome the drawbacks present with autologous bone grafting and/or xenograft materials. Among the CaPs, tricalcium phosphate (TCP) stands out as a good candidate due to its physicochemical properties. The clinical performance of β-TCP has already been proven and established. Nevertheless, the format in which TCP is delivered is also important in terms of clinical handling. This work assessed the in vivo performance of TCP-based bone grafting materials with different formats. Materials studied were a TCP paste (TCP-P), a TCP foam (TCP-F) and TCP granules (TCP-G). A sheep scapula model was used to evaluate the osteogenic performance of these bone grafting materials. All materials performed well in terms of bone regenerative capacity and material resorption. However, TCP-P and TCP-F displayed a more pronounced initial material resorption and also exhibited better handling properties compared to TCP-G. TCP-based materials with improved handling properties, such as TCP-P and TCP-F, which at the same time possess the advantageous properties of β-TCP are suitable bone substitute materials for grafting and reconstruction of bone defects in numerous clinical applications.

Phase transformation behavior of spherical tricalcium phosphate micro-granules prepared by a jet wheel impact atomization and calcination process

Spherical tricalcium phosphate (TCP) micro-granules were prepared using a jet wheel impact atomization and calcination process. Spherical TCP granules were obtained which can exhibit phase transformation between the alpha and beta polymorphs as a function of the heating temperature. The progressive changes in the phosphate group of TCP granules were attributed to the phase transformation. Consequently, such structural changes in the TCP micro-granules can be used to control the dissolution and degradation of TCP through the controlled density and microporosity of the micro-granules.