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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 (, Graphical abstract Image 1, Highlights • Purest β-TCP cylinders ever reported in the literature. • Bulk Ca/P molar ratio influences the physico-chemical properties of β-TCP cylinders. • White light interferometry is a potent method to quantify osteoclastic resorption. • The presence of 1% of β-CPP reduces the in vitro β-TCP resorption rate by 40%.

Background: Platelet-rich fibrin (PRF) is the second-generation platelet concentrate first described by Choukron et al. It incorporates leukocytes, platelets, and growth factors within dense fibrin matrix, can be used in periodontal regeneration alone or in combination with bone grafts. Aim: This study assesses bone fill in intrabony defects, following the use of β tricalcium phosphate (TCP) bone graft with and without PRF. Materials and Methods: Thirty sites with intrabony defects in periodontitis patients were selected, randomly allotted into three groups: Group A open flap debridement (OFD), Group B OFD with β TCP with PRF, and Group C β TCP. Clinical parameters such as plaque index, gingival index, sulcus bleeding index, and PPD recorded at baseline and 6 months. Radiographic parameters include cementoenamel junction (CEJ) to base of defect, CEJ to alveolar crest, depth of defect, and bone fill assessed using the cone-beam computed tomography (CBCT). The comparison between the test group and control group in terms of clinical and radiographical parameters was assessed using the independent sample t-test. Results: Significant reduction in probing depth measurements, defect fill observed in both β TCP with PRF and β TCP alone groups compared to OFD. However, intergroup comparison assessed using the independent sample t-test found to be statistically nonsignificant (P < 0.05 is considered significant). Conclusion: All three treatment strategies resulted in significant reduction in probing depth and bone fill at 6 months. Bone fill achieved in β TCP with PRF was more compared to β TCP alone and OFD at 6 months follow-up. CBCT can be accurately used to assess the morphology of intrabony defect and also in evaluating bone fill.

In this study we compared the bone remodeling of unidirectional (UDPTCP) and spherical porous β-tricalcium phosphate (SPTCP) radiologically in humans. We performed a retrospective analysis of the data of 14 patients (sex, nine men and five women; age, 37–70 years) who underwent medial opening-wedge high tibial osteotomy (MOWHTO) and were followed up for 12 months after surgery. Two wedge-shaped β-TCPs (one UDPTCP and one SPTCP) were cut and placed parallel to each other in the gap. In Group A (eight knees), UDPTCP was implanted anteriorly and SPTCP posteriorly, while in Group B (six knees), SPTCP was implanted anteriorly and UDPTCP posteriorly. Computed tomography (CT) was performed at 1 week, 6 months, and 12 months after surgery, with the CT attenuation values calculated for UDPTCP and SPTCP. In Groups A and B, the CT attenuation values for UDPTCP were significantly lower at 6 and 12 months after surgery compared to those at 1 week (P

Gokcekaya O., Ueda K., Narushima T., et al. Using HAADF-STEM for atomic-scale evaluation of incorporation of antibacterial Ag atoms in a ß-tricalcium phosphate structure. Nanoscale, 12, 31, 16596. https://doi.org/10.1039/d0nr04208k., Structural evaluation of ionic additions in calcium phosphates that enhance their performance is a long-lasting area of research in the field of biomedical materials. Ionic incorporation in ß-tricalcium phosphate (ß-TCP) structures is indispensable for obtaining desirable properties for specific functions and applications. Owing to its complex structure and beam-sensitive nature, determining the extent of ion incorporation and its corresponding location in the ß-TCP structure is challenging. Further, very few experimental studies have been able to estimate the location of Ag atoms incorporated in a ß-TCP structure while considering the associated changes in lattice parameters. Although the incorporation alters the lattice parameters, the alteration is not significant enough for estimating the location of the incorporated Ag atoms. Here, Ag incorporation in a ß-TCP structure was evaluated on atomic scale using scanning transmission electron microscopy (STEM). To the best of our knowledge, this is the first report to unambiguously determine the location of the incorporated Ag atoms in the ß-TCP structure by comparing z-contrast profiles of the Ag and Ca atoms by combining the state-of-art STEM observations and STEM image simulations. The Ag incorporation in the Ca(4) sites of ß-TCP, as estimated by the Rietveld refinement, was in good agreement with the high-angle annular dark-field STEM observations and the simulations of the location of Ag atoms for [001] and [010] zone axes.

The aim of this study is to investigate the efficacy and the effect of the dosage of the slow-released Escherichia coli-derived recombinant human bone morphogenetic protein 2 (ErhBMP-2) functionalized β-tricalcium phosphate (β-TCP) in repairing critical-sized bone defects. The functionalization was implemented by modifying the surface of β-TCP with biomimetic calcium phosphate coating with or without ErhBMP-2. Critical-sized calvarial defects were created in rats and filled with ErhBMP-2 functionalized β-TCP loaded with gradient doses of ErhBMP-2 (0, 50, 100, 150, 200, and 300 μg/g). The blank control group and the autologous bone group were also included. The systemic toxicity was evaluated using routine blood and histopathological examination. The efficiency in bone healing was evaluated using microcomputed tomography, histology, and histometric analyses. Neither local nor systemic adverse effects were found following the implantation of the ErhBMP-2 functionalized β-TCP. The new bone formation was significantly increased in the ErhBMP-2 functionalized β-TCP groups compared with the blank group and the β-TCP with coating only group. The efficacy of the ErhBMP-2 functionalized β-TCP in bone healing was comparable to that of the autologous bone. There was no significant difference in bone formation among all concentrations of ErhBMP-2 (0-300 μg/g). Increased bone maturation was found in the higher concentration groups (150, 200, and 300 μg/g) when compared with the lower concentration groups (50, and 100 μg/g). Our results demonstrated that the ErhBMP-2 functionalized β-TCP could significantly promote bone repairing in critical-sized defects, and it could clinically be a promising substitute for autologous bone. Besides, our results demonstrated that there was a dosage-dependent effect of ErhBMP-2 functionalized β-TCP on bone maturation rather than bone formation. The optimized concentrations of ErhBMP-2 recommended for this kind of model should be in the range of 150-300 μg/g. Bone substitutes functionalized by mammalian-derived recombinant human bone morphogenetic protein 2 (rhBMP-2) have demonstrated to be comparable to the autologous bone in repairing the critical-sized bone defects. To develop a commercial product with more effective cost, Escherichia coli-derived rhBMP-2 (ErhBMP-2) has been produced and evaluated as an alternative to the mammalian-derived rhBMP-2. In this study, we prepared gradient ErhBMP-2 functionalized β-tricalcium phosphate (β-TCP) with biomimetic calcium phosphate coating and investigate their efficacy and dose effects. We revealed the dose effects of the slow-released ErhBMP-2 and demonstrated that ErhBMP-2 functionalized β-TCP could be a promising bone substitute for bone regeneration in clinical settings.

Purpose Autografts, the gold standard treatment for large bone defects, present complications, especially in conditions with reduced bone-repair capacity, such as osteoporosis. Escherichia coli-derived recombinant human bone morphogenesis protein-2 (ErhBMP-2), was used in this study to improve the osteoinductivity of β-tricalcium phosphate (β-TCP). This study evaluated the bone-repair capacity of ErhBMP-2-loaded β-TCP on osteoporosis rabbit model, relative to the sole use of autograft and β-TCP treatments. Methods The osteoporosis rabbit model was induced through ovariectomy and glucocorticoid dosing; 2-cm segmental ulnar defects were created, which were treated with either autograft, β-TCP alone, or ErhBMP-2-loaded β-TCP or left untreated. The quality of newly formed ulnae was evaluated 8 weeks after ulnar surgery through micro-CT, biomechanical, histological, and histomorphometric assessments. Results The osteoporosis rabbit model was developed and maintained till the end of the study. The maximal load and stiffness in the ErhBMP-2-loaded TCP group were significantly higher than those in the autograft group, whereas the TCP-alone group performed similarly as did the untreated group in the force loading and stiffness tests. According to the micro-CT evaluation, the ErhBMP-2-loaded TCP group had significantly higher bone volume relative to the autograft and TCP-alone groups. Histological assessments revealed better defect bridging and marrow formation in the ErhBMP-2-loaded TCP group relative to the TCP-alone group. Mineral apposition rates were significantly higher in the ErhBMP-2-loaded TCP and autograft groups than in the TCP-alone and untreated groups. Conclusion Relative to autografts, ErhBMP-2-loaded TCP, as an alternative grafting material, provides better or comparable healing on critical-sized long bone defects in the osteoporosis rabbit model., Graphical abstract Unlabelled Image, Highlights • Erh-BMP-2 promoted the bone healing ability of β-TCP in osteoporosis animal model. • New bone generated by Erh-BMP-2-loaded β-TCP was stiffer than that generated by autograft. • ErhBMP-2-loaded TCP potentially being an alternative grafting material relative to autograft.

Mesoporous beta tricalcium phosphate (β-TCP) has recently attracted significant interest as an artificial bone tissue in orthopedics. However, a scalable process is required to meet future demands. Spray drying is one of the potential synthesis methods owing to its low cost and scalable production. In this study, various mesoporous β-TCP powders were calcined in the range of 800 to 1100 °C, with particle sizes ranging from ~0.3 to ~1.8 μm, specific surface areas from ~16 to ~64 m2/g, and average pore sizes of 3 nm. Except for the 800 °C calcined powder, the other β-TCP powders (calcination temperatures of 900, 1000, and 1100 °C) exhibited no cytotoxicity. These results indicate that spray-dried mesoporous β-TCP powders were obtained. Finally, the corresponding formation mechanisms are discussed.

When teeth have responded poorly to conventional endodontic treatment or when they cannot be treated adequately by nonsurgical means, surgical endodontics remains the treatment of choice. Healing of apical lesions occurs by repair, most of the time. “Repair is the healing of a wound by tissue that does not fully restore the architecture or function of the affected unit”. Since this is not ideal, newer regenerative procedures that aim to restore lost tissue have been introduced. β ‑Tricalcium phosphate is an alloplastic bone graft material that forms a scaffold for closing the bony defect. It is osteoconductive. Platelet‑rich plasma (PRP) and platelet‑rich fibrin (PRF) are platelet concentrates, rich in growth factors and they promote regeneration by osteoinduction. This article describes cases of bone augmentation with a combination of PRP + β ‑TCP and PRF + β ‑TCP fortreatment of the chronic periapical lesion. The cases were followed for six months and one year and healing was evaluated quantitatively using cone beam computed tomography. Keywords: β ‑Tricalcium phosphate, cone beam computed tomography, platelet‑rich plasma, platelet‑rich fibrin

There has been substantial interest in research aimed at conductive carbon-based supports since the discovery that the electrical stimulus can have dramatic effect on cell behavior. Among these carbon-aerogels decorated with biocompatible polymers were suggested as future materials for tissue engineering. However, high reaction temperatures required for the synthesis of the aerogels tend to impair the stability of the polymeric networks. Herein, we report a synthetic route towards carbon-aerogel scaffolds decorated with biocompatible ceramic nanoparticles of tricalcium phosphate. The composites can be prepared at temperature as high as 1100 °C without significant effect on the morphology of the composite which is comparable with the original aerogel framework. Although the conductivity of the composites tends to decrease with the increasing ceramic content the measured conductivity values are similar to those previously reported on polymer-functionalized carbon-aerogels. The cell culture study revealed that the developed constructs support cell proliferation and provide good cell attachment suggesting them as potentially good candidates for tissue-engineering applications.

The giant cell tumor of bone (GCTB) is a locally aggressive tumor. Reconstruction methods using β-tricalcium phosphate (β-TCP) blocks with strong compression resistance in and around the knee joint for GCTB have been reported. Among six cases of GCTB treated using this method, two recurrent cases revealed osteolysis, predominantly within the β-TCP block based on plain radiographs or computed tomography, while remodeled host bones were preserved. Implanted β-TCP blocks can function as a placeholder to preserve host bone in recurrent cases, leading to a higher probability of joint preservation.

International audience; Although bone formation around and within implants has been intensively studied, the role of pores and pore geometry is still debated. Notwithstanding studies reporting the formation of bone and bone components within pores as small as a few micrometers ('micropores'), bone ingrowth is believed to only occur in pores larger than 100 mu m ('macropores'). A thorough analysis of 10 different porous beta-tricalcium phosphate cylinders (empty set: 8 mm; L: 13 mm) implanted for 2-24 weeks in an ovine model demonstrates ingrowth of mineralized tissue (MT) in pores as small as 1 mu m. This tissue contained calcium phosphate, collagen, and interconnected cells. It formed within the first 3-4 weeks of implantation, extended over several hundred micrometers within the ceramic, and contributed to the majority of the early MT formation (including bone) in the defect. The indentation stiffness of the MT-ceramic composite was significantly higher than that of bone and MT-free ceramic. The presented results substantiate the importance of micropores for optimal bone healing, particularly at early implantation times

We report a case of an acetabular fracture treated using a unidirectional porous β-tricalcium phosphate artificial bone (Affinos®) to surgically repair bone defects. An 82-year-old man sustained an acetabular fracture on the left side and presented with shock on arrival along with impaired vital signs and systolic blood pressure. Upon stabilization, we performed an open reduction and internal fixation. However, there were significant bone defects, which were then fixed using Affinos® (both blocks and granules), an artificial β-tricalcium phosphate bone with a porosity of 57% (pore size: 25–300 μm), characterized by a novel unidirectional porous structure. By 18 months postoperatively, the patient was able to perform stair climbing and absorption and bone fusion around the artificial bone were observed. Affinos® has a frost-like structure, which endows it with good tissue-invasive properties because of the capillary effect. Moreover, it has excellent osteoconduction capability. In this case, both Affinos® blocks and granules showed good affinity, absorption, and bone substitution. Further prospective studies are required to confirm our findings.

Bone grafting is frequently performed in orthopedic surgeries. Artificial bone is a common grafting material. We have developed an absorbable material for bone regeneration with a unique structure: unidirectional porous β-tricalcium phosphate (AffinosⓇ; Kuraray Co., Ltd., Tokyo, Japan). The most distinctive feature of this material is the ease with which blood can rapidly reach its depths by capillary action due to the unidirectional porous structure. It is also characterized by the presence of micropores, which are known to be beneficial for osteoconductivity both on the surface and inside the material. Favorable artificial bone absorption and regeneration with natural bone were observed in cases of clinical bone graft applications in the spine, extremities, benign bone tumor, trauma, and donor sites. Affinos is useful as a novel absorbable material for bone regeneration in various orthopedic surgeries.

Bisphosphonates (BPs) are the most utilized drugs for the treatment of osteoporosis, and are usefully employed also for other pathologies characterized by abnormally high bone resorption, including bone metastases. Due to the great affinity of these drugs for calcium ions, calcium phosphates are ideal delivery systems for local administration of BPs to bone, which is aimed to avoid/limit the undesirable side effects of their prolonged systemic use. Direct synthesis in aqueous medium and chemisorptions from solution are the two main routes proposed to synthesize BP functionalized calcium phosphates. The present review overviews the information acquired through the studies on the interaction between bisphosphonate molecules and calcium phosphates. Moreover, particular attention is addressed to some important recent achievements on the applications of BP functionalized calcium phosphates as biomaterials for bone substitution/repair.

Background Historically, iliac crest bone graft has been used as the graft of choice for lumbar spine fusion procedures. Because fusion techniques have become less invasive, the demand for minimally disruptive grafting options has increased. This prospective study was performed to assess clinical and radiographic outcomes of patients treated with an iliac crest bone graft alternative and lateral lumbar interbody fusion. Methods Fifty degenerative lumbar patients were treated with the extreme lateral approach to interbody fusion and a β-tricalcium phosphate–hydroxyapatite graft with bone marrow aspirate (BMA) at 1 or 2 adjacent levels. BMA was collected from the iliac crest with a bone aspiration needle and applied to the FormaGraft (NuVasive, Inc., San Diego, California) in a 1:1 ratio. Radiolucent cages were filled with FormaGraft strips, granules, or blocks and implanted in a standard fashion. Clinical data were collected at baseline, 6 weeks, and 3, 6, and 12 months and included visual analog scale, Oswestry Disability Index, and Short Form 36 patient-reported assessments. Fusion assessments were made from neutral anteroposterior/lateral radiographs, lateral flexion/extension radiographs, and computed tomography images taken at least 12 months after surgery. Results Forty-four patients treated at 49 levels completed follow-up. The mean patient age was 54.7 ± 10.8 years, and mean body mass index was 30.8 ± 7.7 kg/m2. Radiographic fusion was observed in 41 of 44 assessed levels (93.2%). Blood loss was less than 100 mL in 95.5% of patients. Of the patients, 93.2% spent 1 night or less in the hospital. By the 6-week follow-up, all clinical outcomes were significantly improved (P < .05). Improvements were maintained or increased throughout the course of follow-up. Conclusions This report shows that the technique of extreme lateral approach to interbody fusion in combination with FormaGraft and BMA in the interbody space is a safe and effective treatment option for interbody fusion of the lumbar spine when compared with other approaches and biologic options.

Porous spherical granules of β-tricalcium phosphate (β3-TCP) composed of rod-shaped particles were prepared viaa hydrothermal route. The biological significance ofimplantation of the spherical β-TCP granules for healing of bone defects was analyzed by implantation into 2 mm diameter and 3 mm deep defects created intibiae of 9-week-oldWistar rats. Implantation of spherical β-TCP contributed to regeneration of bone tissue. At 2 and 4 weeks after implantation, numerous alkaline phosphatase-positive cells appeared around the implant and newly formed bone. At 8 weeks after implantation, residualimplants were mostly embedded in bone tissue. Without implantation, bone defects healed with a much lower amount of bone. In addition, bone marrow adipocytes were considerably fewer intibiae with implants compared to tibiae without implants at 4 and 8 weeks after the operation. These data suggested that implanted granules worked as scaffolds to maintainalkaline phosphatase-positive cells and also resulted in less fatty change of bone marrow., Journal of the Ceramic Society of Japan, 119(1386), pp.101-104; 2011

Background: The present study was aimed at comparing the clinical effectiveness of two regenerative techniques - platelet rich plasma (PRP) + bone graft (HA + β TCP) versus bone graft (HA + β TCP) + normal saline in the treatment of periodontal intrabony defects. Materials and Methods: Ten patients diagnosed with chronic periodontitis were enrolled in a randomized split mouth clinical trial. Following phase I therapy the sites were randomly assigned to the test group - PRP + bone graft (HA + β TCP) and control group - saline + bone graft (HA + β TCP). Clinical parameters recorded at baseline and 6 months included plaque index, probing pocket depth, relative attachment levels, and relative gingival margin levels. Hard tissue evaluation was done using digital radiography to evaluate the image intensity and therefore the radioopacity of a desired region of interest in the intrabony defect. Pre- and postoperative comparisons were made between the treatment groups at 6 months. Results: Test group sites showed a significantly higher reduction in pocket depth compared to control group sites. Test group sites showed a significantly higher amount of radioopacity in the regions of interest, indicative of better graft remodeling, compared to control group sites. Conclusion: (HA + β TCP) bone graft appears to be a beneficial material in the treatment of human periodontal intrabony defects. When combined with platelet-rich plasma there is a significantly higher reduction in probing pocket depth, higher gain in attachment levels and higher amount of radio-density seen in the intrabony defects.

Introduction. Bone resorption is a physiological process after tooth extraction. The use of bone substitutes to fill the tooth socket is suggested to prevent bone resorption and establish good bone architecture for implant placement. A pure ?-tricalcium phosphate coated with copolymer (polylactic-polyglycolic acid) as a root analogue, is suitable for filling tooth sockets. Case report. We presented a patient successfully treated with root analogue after extraction of the right second lower premolar. Three months later, the patient was planned for the placement of six TE? ITI dental implants into the mandible. During the surgery, the biopsy of bone-like tissue from the previously treated socket was taken. All the implants were immediately loaded due to good primary stability. Histological analysis of the specimen revealed fibrous healing in the area treated with root analogue. Conclusion. The use of ?-tricalcium phosphate coated with copolymers after tooth extraction enables satisfactory bone architecture for consequent implant treatment.

The paper titled "Restoration of Critical-Sized Defects in the Rabbit Mandible Using Autologous Bone Marrow Stromal Cells Hybridized with Nano-β-tricalcium Phosphate/Collagen Scaffolds" [1] has been retracted upon the authors' request, as they found that there are some wrong results in their paper.

Nano-β-tricalcium phosphate/collagen (n-β-TCP/Col) is considered with good osteoconductivity. However, the therapeutic effectiveness of n-β-TCP/Col scaffolds in combination with autologous bone marrow stromal cells (BMSCs) remains to be elucidated for the repair of critical-sized bone defects. In this study, we found that n-β-TCP/Col scaffolds exhibited high biocompatibilityin vitro. The introduction of BMSCs expandedin vitroto the scaffolds dramatically enhanced their efficiency to restore critical-sized bone defects, especially during the initial stage after implantation. Collectively, these results suggest that autologous BMSCs in n-β-TCP/Col scaffolds have the potential to be applied in bone tissue engineering.

BACKGROUND: Although three-dimensional (3D) β-tricalcium phosphate (β-TCP) scaffolds serve as promising bone graft substitutes for the segmental bone defect treatment, no consensus has been achieved regarding their optimal 3D architecture. METHODS: In this study, we has systematically compared four types of β-TCP bone graft substitutes with different 3D architectures, including two types of porous scaffolds, one type of tubular scaffolds and one type of solid scaffolds, for their efficacy in treating segmental bone defect in a rabbit model. RESULTS: Our study has demonstrated that when compared to the traditional porous and solid scaffolds, tubular scaffolds promoted significantly higher amount of new bone formation in the defect regions as shown by X-ray, micro CT examinations and histological analysis, restored much greater mechanical properties of the damaged bone evidenced by the biomechanical testing, and eventually achieved the complete union of segmental defect. Moreover, the implantation of tubular scaffolds enhanced the neo-vascularization at the defect region with higher bone metabolic activities than others, as indicated by the bone scintigraphy assay. CONCLUSIONS: This study has further the current knowledge regarding the profound influence of overall 3D architecture of β-TCP scaffolds on their in vivo defect healing performance and illuminated the promising potential use of tubular scaffolds as effective bone graft substitute in treating large segmental bone defects.

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WOS: 000309024000013 PubMed ID: 23072285 The choice of augmentation material is a crucial factor in sinus augmentation surgery. Bovine-derived hydroxyapatite (BHA) and beta-tricalcium phosphate (beta-TCP) have been used successfully in sinus augmentation procedures. Choosing one of these materials for sinus augmentation is still controversial. The aim of this clinical study was to compare the biological performance of the new BHA graft material and the well-known synthetic beta-TCP material in the sinus augmentation procedure. The study consisted of 23 patients (12 male and 11 female) who were either edentulous or partially edentulous in the posterior maxilla and required implant placement. A total of 23 two-step sinus-grafting procedures were performed. BHA was used in 13 patients, and beta-TCP was used in 10 patients. After an average of 6.5 months of healing, bone biopsies were taken from the grafted areas. Undecalcified sections were prepared for histomorphometric analysis. The mean new bone formation was 30.13% +/- 3.45% in the BHA group and 21.09% +/- 2.86% in the beta-TCP group (P = .001). The mean percentage of residual graft particle area was 31.88% +/- 6.05% and 34.05% +/- 3.01% for the BHA group and beta-TCP group, respectively (P = .047). The mean percentage of soft-tissue area was 37.99% +/- 5.92% in the BHA group and 44.86% +/- 4.28% in the beta-TCP group (P = .011). Both graft materials demonstrated successful biocompatibility and osteoconductivity in the sinus augmentation procedure. However, BHA appears to be more efficient in osteoconduction when compared with beta-TCP.

The preparation of Mn-containing β-tricalcium phosphate (β-TCP) samples was achieved in two ways: a) transformation of precipitated Mn-containing calcium hydroxyapatite (HA) to β-TCP by heating at 1100 °C, and b) preparation by solid-state reaction of a mixture of CaCO3, (NH4)2HPO4, and Mn(NO3)2 at 1100 °C. Powder X-ray diffraction (XRD) analyses of the samples, obtained by both methods, show well-defined patterns with structural data of the rhombohedral R3c, β-TCP phase. The calculated lattice constants are smaller than those known for β-Ca3(PO4)2 because of substitution of Ca2+ by Mn2+. EPR spectroscopy indeed reveals that manganese is divalent in the samples. Apparently, the Ca(5) site in the β-TCP structure is occupied by Mn2+. The distribution of Mn2+ between the β-TCP and the HA phase in the case of preparation (b) was studied by EPR spectroscopy, and a pronounced preference for the former lattice was found. Micron- and submicron-sized crystals with visible faces were observed by TEM in the case of β-TCP prepared by solid-state reaction, and large micron-sized, droplike-shaped crystals, sensitive to beam radiation, were found in the case of samples prepared by heating HA at elevated temperatures. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

For the preparation of beta-TCP and biphasic calcium phosphates (BCPs, mixtures of hydroxyapatite and beta-TCP), the presence of sodium in the reaction medium results in the incorporation of sodium in the beta-TCP network, by substitution of some calcium sites. Accordingly, a decrease of the unit cell volume of -TCP was observed with increasing sodium substitution. The distribution of sodium in the beta-TCP structure, as a function of the amount incorporated, was probed using 31P and 23Na MAS NMR and 31P{23Na} REDOR experiments. It was shown that an estimation of the sodium content in beta-TCPs could be obtained from the modeling of their 31P MAS NMR spectra. Moreover, the incorporation of sodium in beta-TCPs results in improved mechanical properties, without affecting the biocompatibility of the ceramics.