Biphasic Calcium Phosphate Particles Research Articles

Influence of Biphasic Calcium Phosphate Incorporation Into Alginate Matrices

Biphasic calcium phosphate (BCP), containing β-tricalcium phosphate and hydroxyapatite, was synthesized by co-precipitation method to obtain a biomimetic artificial bone-like composite using calcium nitrate tetrahydrate [Ca(NO3)∙4H2O] as calcium precursor and ammonium dihydrogen phosphate (NH4H2PO4) as phosphorous precursor, maintaining Ca/P ratio of 1.67. The synthesized biphasic calcium phosphate mixture was dispersed in a sodium alginate (Alg) matrix dissolved in distilled water and lyophilized. The chemical structure, possible interactions between components and morphology of the obtained powder and scaffolds were studied through Fourier transform infrared (FT- IR) spectroscopy, X-ray diffraction (XRD) thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) in order to observe the interactions between BCP and the polymer. The particle size of the powder was also analyzed using the dynamic light scattering (DLS) analysis. Calcined powder had a particle size of 1.8 �m. In addition to the low crystalline hydroxyapatite (HA), as the main phase in the dried samples, β-tricalcium phosphate (β-TCP) was formed after the thermal treatment of 1000˚C as shown by XRD and FT-IR. The obtained composite material presented a highly porous microstructure with interconnected layers where the BCP particles were well dispersed. The micro-structure of the scaffolds was influenced with the change in pore dimensions and rearrangement of the layers due to the incorporation of the BCP particles and by the treatment of the scaffolds with CaCl2.

Fabrication of novel bone substitute alginate – N,O-carboxymethyl chitosan – Aldehyde hyaluronic acid – Biphasic calcium phosphate for bone regeneration

Mineralized hydrogels, synthesized by incorporating mineral particles into the hydrogel crosslinking network, have become an effective approach for bone tissue engineering. In this study, hydrogel composites based on alginate, N,O-carboxymethyl chitosan (NOCC), aldehyde hyaluronic acid (AHA) and loaded with biphasic calcium phosphate (BCP) were fabricated by in situ crosslinking. NOCC-AHA hydrogel, forming crosslinks by Schiff base reaction without requiring any chemical linkers or radial light sources, offers a porous scaffold favorable for incorporating with the mineral phase. The integration of BCP – inorganic phase – and alginate within the NOCC-AHA system can be used to supplement mineral agents and reinforcement. Different amounts of BCP particles were investigated to improve cell proliferation. The formation of hydrogel composites was confirmed via scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). In vitro study evidenced that MC3T3 cells were well-attached to hydrogel composites which did not cause cytotoxicity. Furthermore, in vivo study demonstrated that alginate-NOCC-AHA-BCP hydrogels promoted bone healing in the full-thickness calvarial defect mouse model. The obtained results indicated that the fabricated hydrogel composite could be a potential material for bone regeneration with a suitable degradation rate, appropriate pore size, favorable cytocompatibility, high compressive strength, ability to support cell proliferation, and capacity to enhance bone regeneration.

3D gel-printing of hierarchically porous BCP scaffolds for bone tissue engineering

In this study, a conventional technique of porous preparation was used to improve the constructive capability of direct ink writing on microstructures, and the hierarchically porous scaffolds were successfully prepared by 3D gel printing (3DGP). Micron-sized hydroxyapatite (HA) was coated with tricalcium phosphate (TCP) nanopowders synthesized by chemical co-precipitation to form biphasic calcium phosphate (BCP). The random structure of concave micropores was achieved by filling the BCP slurry with PMMA microspheres while successfully controlling the internal porosity of printed filaments. The results showed that the three-stage porous structure was successfully constructed, i.e., macroscopic pores of 1.50-2.00 mm, spherical micropores of 100-200 μm, and inter-powder interstices of 1.00-10.00 μm. Nano-TCP coated micron-HA powders improved the sintering activity of BCP particles. The compressive strength and porosity of the scaffolds sintered at 1400 °C were 2.78 MPa and 84.98%. The hierarchically porous BCP scaffolds had bright applications in bone tissue engineering.

Effect on Rheological Properties and 3D Printability of Biphasic Calcium Phosphate Microporous Particles in Hydrocolloid-Based Hydrogels.

The production of patient-specific bone substitutes with an exact fit through 3D printing is emerging as an alternative to autologous bone grafting. To the success of tissue regeneration, the material characteristics such as porosity, stiffness, and surface topography have a strong influence on the cell–material interaction and require significant attention. Printing a soft hydrocolloid-based hydrogel reinforced with irregularly-shaped microporous biphasic calcium phosphate (BCP) particles (150–500 µm) is an alternative strategy for the acquisition of a complex network with good mechanical properties that could fulfill the needs of cell proliferation and regeneration. Three well-known hydrocolloids (sodium alginate, xanthan gum, and gelatin) have been combined with BCP particles to generate stable, homogenous, and printable solid dispersions. Through rheological assessment, it was determined that the crosslinking time, printing process parameters (infill density percentage and infill pattern), as well as BCP particle size and concentration all influence the stiffness of the printed matrices. Additionally, the swelling behavior on fresh and dehydrated 3D-printed structures was investigated, where it was observed that the BCP particle characteristics influenced the constructs’ water absorption, particle diffusion out of the matrix and degradability.

Fabrication and characterization of a semi-rigid shell barrier system made of polycaprolactone and biphasic calcium phosphate: A novel barrier system for bone regeneration

Nowadays, no barrier membrane serves all purposes of bone augmentation. This study aimed to fabricate a semi-rigid shell barrier system composed of a semi-rigid shell and a covering membrane or a semi-resorbable barrier membrane, based on polycaprolactone (PCL) and biphasic calcium phosphate (BCP) for guided bone regeneration (GBR). A shell and a covering membrane were fabricated by a solvent casting technique based on PCL (70) and BCP (30). The experimental groups were a semi-rigid shell, an airdried membrane, a buffered membrane, and a commercial d-PTFE as a control. Physico-chemical, mechanical properties, and in vitro biocompatibility with osteoblasts and fibroblasts cells were evaluated in all groups. The fabricated materials had rough surfaces with a homogeneous distribution of BCP particles on one side and a smooth surface on the opposite side. The airdried membrane presented a rougher surface on both top and bottom sides (Sq=605.45nm, 556.82nm) than the semi-rigid shell (310.74nm, 424.56nm) and the buffered membrane (277.9nm, 306.98nm), respectively. The pore sizes of the airdried membrane (25-40μm) were larger than the semi-rigid shell (5-40μm) and the buffered membrane (5-25μm). The porosities of the airdried and buffered membranes (∼40%) were higher than the semi-rigid shell (∼20%) significantly (p<0.05). All fabricated materials were hydrophilic, with the lowest water contact angle in the semi-rigid shell (54.7°±3.06°), then the airdried (61.15°±4.76°), and the buffered (75.74°±2.8°) respectively. The semi-rigid shell resisted a higher load on compressive force (18.82±2.72N) than the d-PTFE membrane (4.23±0.5N). The tensile stress of the buffered membrane (2.544±0.19MPa) was not different from the d-PTFE (2.908±0.12MPa) but was higher than the airdried membrane (1.302±0.13MPa) significantly (P<0.05). The airdried membrane had reached 100% swelling ability within 1h, which was significantly faster than the buffered membrane (12h) and the semi-rigid shell (7 days), and they were slowly degraded by lysozyme at 6 months (airdried: 24.88%±0.96%, buffered: 13.67%±0.55%, and semi-rigid: 8.62%±0.88%). All fabricated membranes showed no toxicity to osteoblast and fibroblast cells. The semi-rigid shell and the covering membranes demonstrated suitable physical and mechanical properties, and biocompatibility, and can be assembled as the novel semi-rigid shell barrier system for bone regeneration.

Proteomic analysis identified LBP and CD14 as key proteins in blood/biphasic calcium phosphate microparticle interactions

Immediately upon implantation, scaffolds for bone repair are exposed to the patient's blood. Blood proteins adhere to the biomaterial surface and the protein layer affects both blood cell functions and biomaterial bioactivity. Previously, we reported that 80-200 µm biphasic calcium phosphate (BCP) microparticles embedded in a blood clot, induce ectopic woven bone formation in mice, when 200-500 µm BCP particles induce mainly fibrous tissue. Here, in a LC-MS/MS proteomic study we compared the differentially expressed blood proteins (plasma and blood cell proteins) and the deregulated signaling pathways of these osteogenic and fibrogenic blood composites. We showed that blood/BCP-induced osteogenesis is associated with a higher expression of fibrinogen (FGN) and an upregulation of the Myd88- and NF-κB-dependent TLR4 signaling cascade. We also highlighted the key role of the LBP/CD14 proteins in the TLR4 activation of blood cells by BCP particles. As FGN is an endogenous ligand of TLR4, able to modulate blood composite stiffness, we propose that different FGN concentrations modify the blood clot mechanical properties, which in turn modulate BCP/blood composite osteoactivity through TLR4 signaling. The present findings provide an insight at the protein level, into the mechanisms leading to an efficient bone reconstruction by blood/BCP composites. Statement of significanceUpon implantation, scaffolds for bone repair are exposed to the patient's blood. Blood proteins adhere to bone substitute surface and this protein layer affects both biomaterial bioactivity and bone healing. Therefore, for the best outcome for patients, it is crucial to understand the molecular interactions between blood and bone scaffolds. Biphasic calcium phosphate (BCP) ceramics are considered as the gold standard in bone reconstruction surgery. Here, using proteomic analyses we showed that the osteogenic properties of 80-200 µm BCP particles embedded in a blood clot is associated with a higher expression of fibrinogen. Fibrinogen upregulates the Myd88- and NF-κB-dependent TLR4 pathway in blood cells and, BCP-induced TLR4 activation is mediated by the LBP and CD14 proteins.

Osteotome-mediated sinus floor elevation using an in situ hardening biphasic calcium phosphate bone graft substitute compared to xenograft: A randomized controlled clinical trial.

To assess osteotome-mediated sinus floor elevation (OMSFE) with simultaneous implant placement using an in situ hardening biphasic calcium phosphate (BCP) compared to xenograft as a control. Patient in need for sinus floor augmentation in one or both sinuses were selected for this randomised controlled clinical trial. Sites presenting a residual sinus floor height of 3-6 mm and eligible for OMSFE were randomly assigned to receive either BCP (test) or xenograft particles (control). CBCT scans were performed before and at the time of implant loading (180 days). The difference in sinus floor height gain between the two groups was set as the primary endpoint parameter for equivalence testing. The implant insertion torque (ITV) was recorded and Implant stability quotients (ISQ) was assessed upon implant placement, abutment connection (160 days) and implant loading (180 days). A total of 54 sinus lifts were performed in 42 patients including 12 bilateral cases. Four implants failed (two in each group) and a total of six patients were lost to follow-up. Statistical analysis of sinus floor height revealed no significant differences (p < 0.05) between groups at baseline nor at 180 days after augmentation. There was no statistical difference in sinus floor height gain between the two groups as supported by the 90% confidence intervals of the difference between groups. Good primary implant stability was confirmed in both treatment groups by ITV and ISQ measurements. Within the limits of this study, it can be concluded that OMSFE using in situ hardening BCP particles results in equivalent sinus floor height gain than using xenograft particles but offers an easier application.

Tissue response to biphasic calcium phosphate covalently modified with either heparin or hyaluronic acid in a mouse subcutaneous implantation model.

Biphasic calcium phosphate (BCP) materials are widely employed as bone substitute materials due to their resorption/degradation properties. Inflammation after implantation of such materials represents a prerequisite for bone tissue repair and regeneration but can be also problematic if it is not only transient and if it is followed by fibrosis and scarring. Here, we modified BCP covalently with hyaluronan (HA) and heparin (Hep), glycosaminoglycans that possess anti-inflammatory properties. Beside the characterization of particle surface properties, the focus was on in vivo tissue response after subcutaneous implantation in mice. Histological analysis revealed a decrease in signs of inflammatory response to BCP when modified with either HA or Hep. Reduced vascularization after 30 days was noticed when BCP was modified with either HA or Hep with greater cellularity in all examined time points. Compared to plain BCP, expression of endothelial-related genes Flt1 and Vcam1 was higher in BCP-HA and BCP-Hep group at day 30. Expression of osteogenesis-related genes Sp7 and Bglap after 30 days was the highest in BCP group, followed by BCP-Hep, while the lowest expression was in BCP-HA group which correlates with collagen amount. Hence, coating of BCP particles with HA seems to suppress inflammatory response together with formation of new bone-like tissue, while the presence of Hep delays the onset of inflammatory response but permits osteogenesis in this subcutaneous bone-forming model. Transferring the results of this study to other coated materials intended for biomedical application may also pave the way to reduction of inflammation after their implantation.

An in vitro study on the key features of Poly L-lactic acid/biphasic calcium phosphate scaffolds fabricated via DLP 3D printing for bone grafting

The main aim of this study was to assess the influence of adding BCP particles on enhancing essential properties of PLLA matrix scaffolds for bone grafting purpose. Poly L-lactic acid (PLLA)/biphasic calcium phosphate (BCP) scaffolds were fabricated via a digital light processing (DLP) 3D printer, with 70% porosity and 600 µm pore size. DLP method was utilized to generate scaffolds with sophisticated geometry, and the bio-composite material was introduced to benefit from positive aspects of polymeric/inorganic substances for bone regeneration. The selected BCP contents were 22.5, and 45 wt% compared with the control specimens with no content. Morphology, exact amount of BCP concentration as well as their distribution were assessed using computerized tomography (µ-CT), thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). Moreover, in vitro biodegradability, cell viability and attachment of the specimens were also investigated. The results showed that in spite of decreasing effect of BCP particles on the mechanical properties of the printed scaffolds, cell adherence and hydrophilicity of the samples were considerably improved. Moreover, a 22.5 wt% of BCP content was found to be an optimum amount to preserve the mechanical properties during biodegradation. The paper showed the effectiveness of adding BCP particles as a biocompatible ceramic to enhance properties of the scaffolds for dental bone regeneration.

Distinctive bone regeneration of calvarial defects using biphasic calcium phosphate supplemented ultraviolet-crosslinked collagen membrane.

PurposeTo overcome several drawbacks of chemically-crosslinked collagen membranes, modification processes such as ultraviolet (UV) crosslinking and the addition of biphasic calcium phosphate (BCP) to collagen membranes have been introduced. This study evaluated the efficacy and biocompatibility of BCP-supplemented UV-crosslinked collagen membrane for guided bone regeneration (GBR) in a rabbit calvarial model.MethodsFour circular bone defects (diameter, 8 mm) were created in the calvarium of 10 rabbits. Each defect was randomly allocated to one of the following groups: 1) the sham control group (spontaneous healing); 2) the M group (defect coverage with a BCP-supplemented UV-crosslinked collagen membrane and no graft material); 3) the BG (defects filled with BCP particles without membrane coverage); and 4) the BG+M group (defects filled with BCP particles and covered with a BCP-supplemented UV-crosslinked collagen membrane in a conventional GBR procedure). At 2 and 8 weeks, rabbits were sacrificed, and experimental defects were investigated histologically and by micro-computed tomography (micro-CT).ResultsIn both micro-CT and histometric analyses, the BG and BG+M groups at both 2 and 8 weeks showed significantly higher new bone formation than the control group. On micro-CT, the new bone volume of the BG+M group (48.39±5.47 mm3) was larger than that of the BG group (38.71±2.24 mm3, P=0.032) at 8 weeks. Histologically, greater new bone area was observed in the BG+M group than in the BG or M groups. BCP-supplemented UV-crosslinked collagen membrane did not cause an abnormal cellular reaction and was stable until 8 weeks.ConclusionsEnhanced new bone formation in GBR can be achieved by simultaneously using bone graft material and a BCP-supplemented UV-crosslinked collagen membrane, which showed high biocompatibility and resistance to degradation, making it a biocompatible alternative to chemically-crosslinked collagen membranes.

Evaluation of the Apical Complex and the Coronal Pulp as a Stem Cell Source for Dentin-pulp Regeneration

IntroductionThis study compared the stemness and differentiation potential of stem cells derived from the apical complex (apical complex cells [ACCs]) and coronal pulp (dental pulp stem cells [DPSCs]) of human immature permanent teeth with the aim of determining a more suitable source of stem cells for regeneration of the dentin-pulp complex. MethodsACC and DPSC cultures were established from 13 human immature permanent teeth using the outgrowth method. The proliferation capacity and colony-forming ability of ACCs and DPSCs were evaluated. ACCs and DPSCs were analyzed for mesenchymal stem cell markers using flow cytometry. The adipogenic and osteogenic differentiation potential of ACCs and DPSCs were evaluated using the quantitative real-time polymerase chain reaction and histochemical staining. ACCs and DPSCs were transplanted subcutaneously in immunocompromised mice using macroporous biphasic calcium phosphate as a carrier. The histomorphologic characteristics of the newly formed tissues were verified using hematoxylin-eosin staining and immunohistochemical staining. Quantitative alkaline phosphatase analysis and quantitative real-time polymerase chain reaction using BSP, DSPP, POSTN, and ColXII were performed. ResultsACCs and DPSCs showed similar cell proliferation potential and colony-forming ability. The percentage of mesenchymal stem cell markers was similar between ACCs and DPSCs. In the in vitro study, ACCs and DPSCs showed adipogenic and osteogenic differentiation potential. In the in vivo study, ACCs and DPSCs formed amorphous hard tissue using macroporous biphasic calcium phosphate particles. The quantity and histomorphologic characteristics of the amorphous hard tissue were similar in the ACC and DPSC groups. Formation of periodontal ligament–like tissue, positive to Col XII, was observed in ACC transplants, which was absent in DPSC transplants. ConclusionsACCs and DPSCs showed similar stemness, proliferation rate, and hard tissue–forming capacity. The notable difference was the periodontal ligament–like fiber-forming capacity of ACCs, which indicates the presence of various lineages of stem cells in the apical complex compared with the coronal pulp. Regarding regeneration of the dentin-pulp complex, the coronal pulp can be a suitable source of stem cells considering its homogenous lineages of cells and favorable osteo/odontogenic differentiation potential.

Sinus floor elevation using particulate PLGA-coated biphasic calcium phosphate bone graft substitutes: A prospective histological and radiological study.

Poly (lactic-co-glycolic acid) (PLGA) is widely used for the development of delivery systems for drugs and therapeutic biomolecules in tissue engineering applications. Particles of biphasic calcium phosphate can be covered by PLGA to change their manipulating characteristics. Aim of this study was to investigate the radiological and histomorphometric results of the use of PLGA-coated biphasic calcium phosphate granules in sinus floor elevation and to analyze the underlying molecular processes by immunohistochemical staining. A randomized clinical study was designed to include patients in need of sinus floor elevation. Patients were assigned to receive either PLGA-coated biphasic calcium phosphate particles (group I) or the equivalent but noncoated particles (group II). Cone beam computed tomography (CBCT) scans were performed before and 6 months after the procedure to assess the bone height gain. At the time of implant placement, bone core biopsies were obtained at the site of implant placement. Histological sections were subjected to histomorphometric and immunohistochemical evaluation of differentiation markers (Musashi-1 [MSI1]). No statistically significant differences were observed between groups for the radiologic parameters. No differences were observed histologically or histomorphometrically. However, PLGA-coated particles (group I) were more colonized by MSI1-positive osteoblast precursors (P = 0.0001, chi-squared test) and were penetrated by more CD34-positive vascular structures (P = 0.001, chi-squared test) than noncoated particles (group II). PLGA-coated particles are associated with more MSI11-positive cells and more extensive microvascularization than noncoated particles.

Synthesis of Hydroxyapatite, β-Tricalcium Phosphate and Biphasic Calcium Phosphate Particles to Act as Local Delivery Carriers of Curcumin: Loading, Release and In Vitro Studies.

The successful synthesis of hydroxyapatite (HA), β-Tricalcium phosphate (β-TCP) and two biphasic mixtures (BCPs) of the two was performed by means of wet precipitation. The resulting crystals were characterized and the BCP composition was analyzed and identified as 13% HA—87% TCP and 41% HA—59% TCP. All samples were treated with curcumin solutions, and the degree of curcumin loading and release was found to be proportional to the TCP content of the ceramic. No further cytotoxicity was observed upon MG-63 treatment with the curcumin-loaded ceramics. Finally, the alkaline phosphatase activity of the cells was found to increase with increasing content of TCP, which provides an encouraging proof of concept for the use of curcumin-loaded synthetic biomaterials in bone remodeling.

Combination of blood and biphasic calcium phosphate microparticles for the reconstruction of large bone defects in dog: A pilot study.

We previously reported that biphasic calcium phosphate (BCP) microparticles embedded in a blood clot induces ectopic bone formation in mice and repairs a critical femoral defect in rat. The present pilot study aimed to evaluate in dog and in two models of large defects the efficacy of this composite named "blood for reconstruction of bone" (BRB). We show here that BRB is a cohesive biomaterial easy to prepare from dog autologous blood and to mold to fill large bone defects. First in a model of cylindrical femoral condyle defect, the BRB was compared with BCP particles alone. After 8 weeks, this revealed that the amount of mature bone was slightly and significantly higher with BRB than with BCP particles. Second, in a model consisting in a 2 cm-long critical interruptive defect of the ulna, the BRB was compared with autologous bone. After 6 months, we observed that implantation of BRB can induce the complete reconstruction of the defect and that newly formed bone exhibits high regenerative potential. Comparison with the results obtained with autologous bone grafting strongly suggests that the BRB might be an efficient biomaterial to repair large bone defects, as an alternative or in addition to autologous bone. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1842-1850, 2018.

Effect of flapless ridge preservation with two different alloplastic materials in sockets with buccal dehiscence defects-volumetric and linear changes.

To test whether or not one out of two alloplastic materials used for ridge preservation (RP) is superior to the other in terms of volumetric and linear ridge changes over time. In 16 adult beagle dogs, the distal roots of P3 and P4 were extracted and 50% of the buccal bone plate removed. Ridge preservation was performed randomly using two different alloplastic bone grafting substitutes (poly lactic-co-glycolic acid (PLGA) coated biphasic calcium phosphate particles consisting of 60% hydroxyapatite (HA) and 40% beta-tricalcium phosphate (ß-TCP=test 1), (a biphasic calcium phosphate consisting 60% HA and 40% ß-TCP=test 2) and a resorbable collagen membrane or a control group (sham). Sacrifice was performed at three time-points (4, 8, 16weeks later). Impressions were taken before extraction, after RP, and at sacrifice, allowing for assessment of volumetric changes. A multi-way ANOVA was computed, and partial Type-II F tests were performed. Both ridge preservation procedures minimized the volume loss compared to spontaneous healing. The median buccal volume changes between pre-extraction and sacrifice were - 1.76mm (Q1 = - 2.56; Q3 = - 1.42) for test 1, - 1.62mm (Q1 = - 2.06; Q3 = - 1.38) for test 2, and - 2.42mm (Q1 = - 2.63; Q3 = - 2.03) for control. The mean ridge width measurements did not show statistically significant differences between test 1 (- 2.51mm; Q1 = - 3.25; Q3 = - 1.70) and test 2 (- 2.04mm; Q1 = - 3.82; Q3 = - 1.81) (p = 0.813), but between test and control (- 3.85mm; Q1 = - 5.02; Q3 = - 3.27) (p = 0.003). Both RP techniques were successful in maintaining the buccal contour from pre-extraction to sacrifice to a similar extent and more favorable compared to spontaneous healing. Alloplastic materials can successfully be used for RP procedures.

The use of a biphasic calcium phosphate in a maxillary sinus floor elevation procedure: a clinical, radiological, histological, and histomorphometric evaluation with 9- and 12-month healing times

BackgroundThis study evaluates the clinical, radiological, histological, and histomorphometric aspects of a fully synthetic biphasic calcium phosphate (BCP) (60% hydroxyapatite and 40% ß-tricalcium phosphate), used in a human maxillary sinus floor elevation (MSFE) procedure with 9- and 12-month healing time.MethodsA unilateral MSFE procedure, using 100% BCP, was performed in two series of five patients with healing times of 9 and 12 months respectively. Clinical and radiological parameters were measured up to 5 years postoperatively. Biopsy retrieval was carried out during dental implants placement. Histology and histomorphometry were performed on 5-μm sections of undecalcified bone biopsies.ResultsThe MSFE procedure with BCP showed uneventful healing in all cases. All dental implants appeared to be well osseointegrated after 3 months. Radiological evaluation showed less than 1 mm tissue height loss from MSFE to the 5-year follow-up examination. No signs of inflammation were detected on histological examination. Newly formed mineralized tissue was found cranially from the native bone. The BCP particles were surrounded by connective tissue, osteoid islands, and newly formed bone. Mineralized bone tissue was in intimate contact with the BCP particles. After 12 months, remnants of BCP were still present. The newly formed bone had a trabecular structure. Bone maturation was demonstrated by the presence of lamellar bone. Histomorphometric analysis showed at 9 and 12 months respectively an average vital bone volume/total volume of 35.2 and 28.2%, bone surface/total volume of 4.2 mm2/mm3 and 8.3 mm2/mm3, trabecular thickness of 224.7 and 66.7 μm, osteoid volume/bone volume of 8.8 and 3.4%, osteoid surface/bone surface (OS/BS) of 42.4 and 8.2%, and osteoid thickness of 93.9 and 13.6 μm.ConclusionsMFSE with BCP resulted in new bone formation within the augmented sinus floor and allowed the osseointegration of dental implants in both groups. From a histological and histomorphometric perspective, a 9-month healing time for this type of BCP may be the optimal time for placement of dental implants.

Poly(trimethylene carbonate)-based composite materials for reconstruction of critical-sized cranial bone defects in sheep

PurposeThe use of ceramic materials in repair of bone defects is limited to non-load-bearing sites. We tested poly(trimethylene carbonate) (PTMC) combined with β-tricalcium phosphate or biphasic calcium phosphate particles for reconstruction of cranial defects. Materials and methodsPTMC-calcium phosphate composite matrices were implanted in cranial defects in sheep for 3 and 9 months. Micro-computed tomography quantification and histological observation were performed for analysis. ResultsNo differences were found in new bone formation among the defects left unfilled, filled with PTMC scaffolds, or filled with either kind of PTMC-calcium phosphate composite scaffolds. Porous β-TCP scaffolds as control led to a larger amount of newly formed bone in the defects than all other materials. Histology revealed abundant new bone formation in the defects filled with porous β-TCP scaffolds. New bone formation was limited in defects filled with PTMC scaffolds or different PTMC-calcium phosphate matrices. PTMC matrices were degraded uneventfully. New bone formation within the defects followed an orderly pattern. ConclusionsPTMC did not interfere with bone regeneration in sheep cranial defects and is suitable as a polymer matrix for incorporating calcium phosphate particles. Increasing the content of calcium phosphate particles in the composite matrices may enhance the beneficial effects of the particles on new bone formation.

Maxillary Sinus Grafting With Biphasic Bone Ceramic or Autogenous Bone: Clinical, Histologic, and Histomorphometric Results From a Randomized Controlled Clinical Trial.

The present, randomized, controlled clinical trial compared the histologic and histomorphometric results from maxillary sinus augmentation with either biphasic calcium phosphate (BCP) (60% hydroxyapatite and 40% β-tricalcium phosphate) or autogenous bone (AB) as bone-grafting materials. Ten patients received bilateral sinus elevation surgery with intraoral AB chips (control group) on one side and BCP (test group) on the contralateral side. After a healing period of 6 to 8 months, implant sites were created and trephine cores were harvested for histological and histomorphometric analysis of the grafted areas. The histological examination of biopsies showed BCP particles interconnected by bridges of a vital newly formed bone. Histomorphometry demonstrated that the amount of newly formed bone in the control group (36.8%) was significantly greater than that in the BCP (28.2%) group (P = 0.0032). BCP and AB cores revealed an average of residual graft particles of 32.9% and 4.8%, respectively. The average percentage of soft tissue components was 38.9% in the BCP cores and 58.4% in the AB cores. Based on our findings, the amount of vital bone formation was significantly higher for AB than that for BCP. However, BCP seemed to be a biocompatible and osteoconductive material that can be used with success as a bone substitute in maxillary sinus procedures.

Maxillary Sinus Floor Augmentation Using Biphasic Calcium Phosphate and a Hydrogel Polyethylene Glycol Covering Membrane: An Histological and Histomorphometric Evaluation.

Maxillary sinus floor augmentation with a lateral approach is usually performed using a bone substitute covered with standard collagen or a synthetic barrier membrane to prevent soft tissue ingrowth within the bone graft. The purpose of this case series was to evaluate a polyethylene glycol (PEG) membrane with a hydrogel consistency, used to protect the lateral sinus anstrotomy, by analyzing the histological quality and histomorphometric quantity of newly formed bone (NB) in a maxillary sinus graft using biphasic calcium phosphate (BCP). Fifteen sinuses were grafted from 12 patients. Six months after the maxillary sinus floor augmentation, bone biopsies were harvested from 7 patients during the implant placement second-step surgery. The histomorphometric evaluation of the 7 grafted sinuses showed mean values of 27.4 ± 4.6% for NB, 26.9 ± 5.4% for remaining BCP particles, and 45.7 ± 6.0% for connective tissue/bone marrow. No implant failure was observed in the 14- to 45-month follow-up period after maxillary sinus floor augmentation procedure and in the 8- to 39-month follow-up period after implant loading. The use of a hydrogel PEG membrane to protect BCP proved to be a valuable grafting procedure to enhance the vital bone formation in the maxillary sinus floor augmentation procedure.

Novel bioceramic-reinforced hydrogel for alveolar bone regeneration.

The osseointegration of dental implants and their consequent long-term success is guaranteed by the presence, in the extraction site, of healthy and sufficient alveolar bone. Bone deficiencies may be the result of extraction traumas, periodontal disease and infection. In these cases, placement of titanium implants is contraindicated until a vertical bone augmentation is obtained. This goal is achieved using bone graft materials, which should simulate extracellular matrix (ECM), in order to promote osteoblast proliferation and fill the void, maintaining the space without collapsing until the new bone is formed. In this work, we design, develop and characterize a novel, moldable chitosan-pectin hydrogel reinforced by biphasic calcium phosphate particles with size in the range of 100-300μm. The polysaccharide nature of the hydrogel mimics the ECM of natural bone, and the ceramic particles promote high osteoblast proliferation, assessed by Scanning Electron Microscopy analysis. Swelling properties allow significant adsorption of water solution (up to 200% of solution content) so that the bone defect space can be filled by the material in an in vivo scenario. The incorporation of ceramic particles makes the material stable at different pH and increases the compressive elastic modulus, toughness and ultimate tensile strength. Furthermore, cell studies with SAOS-2 human osteoblastic cell line show high cell proliferation and adhesion already after 72h, and the presence of ceramic particles increases the expression of alkaline phosphatase activity after 1week. These results suggest a great potential of the developed moldable biomaterials for the regeneration of the alveolar bone. The positive fate of a surgical procedure involving the insertion of a titanium screw still depends on the quality and quantity of alveolar bone which is present in the extraction site. Available materials are basically hard scaffold materials with un-predictable behavior in different condition and difficult shaping properties. In this work we developed a novel pectin-chitosan hydrogel reinforced with ceramic particles. Polysaccharides simulate the extracellular matrix of natural bone and the extensive in vitro cells culture study allows to assess that the incorporation of the ceramic particles promote a pro-osteogenic response. Shape control, easy adaption of the extraction site, predictable behavior in different environment condition, swelling properties and an anti-inflammatory response are the significant characteristics of the developed biomaterial.