Papers by Keyword: Calcium Phosphate Cement (CPC)

Abstract: Direct pulp capping (DPC) is one of the treatment plans for deep caries with mechanical pulp exposure that can replace invasive treatments. This study aimed to assess the apatite-forming ability and solubility of a calcium phosphate cement (CPC) modified with bioactive glass (BG) as a potential bioactive material for DPC.Three different biomaterials including CPC, BG, and CPC/BG composite were used in this study. For bioactivity evaluation, specimens were immersed in simulated body fluid (SBF) for 5 time periods (3, 7, 14, 21 and 28 days). The samples were analyzed by SEM, EDS and XRD to confirm the formation of hydroxyapatite. The solubility was calculated by measuring the initial and final mass according to the ISO 6876 specifications.According to the results of this study, SEM observations and XRD analysis revealed higher formation of hydroxyapatite crystals in the CPC/BG Group and also at the shorter time than those in the CPC and BG groups. Concerning solubility, the CPC group showed the most solubility after 7 days and the BG group showed the lowest one. At this time the difference between CPC and BG groups was statistically meaningful (p value=0.003). After 30 days the CPC/BG group exhibited the lowest solubility value. At the day 30, the CPC and BG groups showed significant difference in their solubility (p value=0.04).).Based on the results, addition of BG to CPC improved bioactivity properties of CPC material and did not affect its solubility adversely. The CPC/BG composite seems to be a promising material for DPC. Further in vivo studies are needed to prove its clinical success.

Abstract: The calcium phosphate cements (CPCs) based on α-tricalcium phosphate (α-TCP) are highly attractive for use in medicine and odontology, since they have similar chemical and phase composition of mineral phase of bones (calcium deficient hydroxyapatite (CDHA)). However, one of the biggest difficulties for use of this type of cement is its low mechanical strength due to the presence of undesirable phases, such as β-tricalcium phosphate. The route for obtaining α-TCP is at high temperature by solid state reaction, mixing calcium carbonate and calcium pyrophosphate. The aim of this work was to obtain calcium phosphate cements with improved strength, by studying the obtaining of α-TCP at temperatures of 1300, 1400 and 1500°C. The samples were analyzed by crystalline phases, pH, setting time, particle size, in vitro test (Simulated Body Fluid), porosity, density and compressive strength. The results show that the synthesis temperatures influence strongly the phases of powders obtained and the mechanical properties of cement, being unnecessary quenching for obtaining pure α-TCP.

Abstract: The Calcium Phosphate Cement (CPC) are bone substitutes with great potential for use in orthopedics, traumatology and dentistry due to its biocompatibility, bioactivity and osteoconductivity, and form a paste that can be easily shaped and placed into the surgical site. However, CPCs have low mechanical strength, which equals the maximum mechanical strength of trabecular bone. In order to assess the strength and time to handle a CPC composed primarily of alpha phase, were added sodium alginate (1%, 2% and 3% wt) and an accelerator in an aqueous solution. The cement powder was mixed with liquid of setting, shaped into specimens and evaluated for apparent density and porosity by Archimedes method, X-ray diffraction and compressive strength. A significant increase in compressive strength by adding sodium alginate was verified.

Abstract: The calcium phosphate cements (CPCs) have attracted great interest for use in orthopedics and dentistry as replacements for damaged parts of the skeletal system,showing good biocompatibility and osseointegration. These characteristics allow its use as a bone graft.Several studies in literature have shown that the addition of polymeric additives has a strong influence on the mechanical properties of cement. The low mechanical strength is the main impediment to a broader use of calcium phosphate bone cement (CPCs) as implant material. The aim of this work was evaluate the strength of a CPC based on α-tricalcium phosphate, with polymeric additions. CPC was synthesized and sodium alginate were added (1%, 2% and 3% by weight) and ammonium polyacrylate (3%; dispersant) in aqueous solution. Specimens were molded and evaluated for density, pH, porosity, in vitro test (Simulated Body Fluid),crystalline phases and mechanical strength. The results show the increase of the mechanical properties of cement when added with sodium alginate and dispersant.

Abstract: The Calcium Phosphate Cement (CFC) has been used as filling material for bone defects because of osteoconductivity properties, bioactivity and biocompatibility. Recent studies, mostly in animals, indicate its use as an adjunct to treatment with osseointegrated implants. Thus this work aims reporting the event in which post-extraction socket was filled with CFC-based α-tricalcium phosphate and calcium sulfate and after four months, the implant was installed through the cement which was not reabsorbed with good primary stability. Upon reopening of the implants after six months, the clinical appearance of peri-implant region was considered normal. Radiographically, there wasnt radiopaque appearance of CFCs in the alveolar region of the test anymore. Histologically, remaining CFC in direct contact with bone without intervening fibrous connective tissue was noticed. Its concluded that the CFC showed osteoconductive behavior. The material tested seems to be an acceptable option for filling the post-extraction socket with the purpose of maintaining bone volume, however, more research is needed to generalize the indication.

Abstract: In this paper, calcium sulfate hemihydrate (CSH) was added into silk fibroin/calcium phosphate (SF/CP) composites. The macropores formed by the SF was connected by micropores formed from rapid degradation of CSH, so that the structure of the composites is more close to the natural bone. The results indicated that the range of pore sizes around 30 - 308 microns were formed in the composites by SF. Compared to SF/CP composites without CSH, the injectability decreased, but the rate were both above 90%; the setting time increased, but were both less than 16min; the porosity increased. When the proportion of CSH was greater than 10%, the morphology of the product of setting reaction, i.e. the hydroxyapatite (HA) crystals, was influenced. When the proportion of CSH was less than 10%, the HA crystals appeared to be needle-like and plate-like crystals. When the proportion of CSH was greater than 10%, HA crystals were needle-like. The added amount of CSH had significant effects on compressive strength and work-of-compressive. The compressive strength and work-of-compressive decreased with increasing of CSH content in the composites.

Abstract: In this study, the high purity tetracalcium phosphate (TTCP) was prepared conveniently after studying the effect of cooling method on the purity of TTCP. The influence of liquid-to-powder (L/P) ratio on the properties of self-setting silk fibroin/calcium phosphate composites was studied. The results showed that the temperature of the furnace had a significant influence on the purity of TTCP when samples were removed from the furnace. Whether using N2 or not had no obvious effect on the purity of TTCP when the temperature declined from 1500°C to 1300°C. The setting time of composites became longer with the increase of L/P ratio in a range 0.32 - 0.39 ml/g, but all less than 15min. The injectability of the composites improved significantly as the L/P ratio increased. The compressive strength of composites reached maximum at the L/P ratio of 0.34 ml/g. The compressive strength decreased with the increase of L/P ratio greater than 0.34ml/g. The L/P ratio had no significant effect on the structure of the composites and the rod-like crystal of hydroxyapatite appeared in all the hardening-body of composites.

Abstract: Hydroxyapatite whisker was the reinforcement phase to prepare whisker/calcium phosphate cement composites, which was obtained by homogeneous precipitation method, with 2.5~15 microns in length, 2~30 length/diameter ratio. Mechanical properties and microstructure of composites were tested. With the increase of hydroxyapatite whisker addition, composites strength reduces after the first rise. When hydroxyapatite whisker is added to 4%(wt), the composite achieves the maximum strength. SEM method was used to observe fracture microstructures of composite materials. As a result, dispersion degree of the HA whisker affects the strength of the material. Too much whiskers can form agglomerates, which weaken composite strength.

Abstract: Apatite wollastonite glass ceramic (AW-GC) (34.2% SiO₂, 44.9% CaO, 16.3%P₂O₅, 4.6% MgO, 0.5% CaF₂) was added into a brushite bone cement, which composed of β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP) and monocalcium phosphate monohydrate (Ca (H₂PO₄)2H₂O, MCPM) in powder phases. Cement was prepared using a 3 β-TCP:2 MCPM in weight ratio. To evaluate the effect of AW-GC on the mechanical strength and degradability of brushite bone cement, the powder phases and 1 wt.% of chitosan dissolved in 5 wt.% of citric acid solution were mixed and soaked in simulated body fluid solution at 37 ^°C for 1, 3, 5,7 and 14 days, respectively. The compressive strength and setting time of AW-GC added in brushite bone cement were studied and compared with pure brushite cement. The pH values increased with addition of AW-GC. Additionally, the obtained brushite bone cements were characterized by XRD, SEM techniques.

Abstract: Osteoporosis is the most common metabolic bone disease and the most common cause of fractures in older adults. Vertebral compression fracture (VCF) is the most common complication in patients with osteoporosis. At present, vertebroplasty (VP) and kyphoplasty (KP) are two minimally invasive techniques used to treat osteoporotic vertebral compression fractures. In clinical use, KP and VP have stable and reliable therapeutic effects. However, there are still some complications and issues surrounding KP and VP application, and for long-term clinical follow-up. Thus, it is important to continue to improve the technology of the filler materials used in KP and VP in order to evolve the biomechanical characteristics of the postoperative vertebra, and to reduce the incidence of complications. The filler materials used for both techniques require good biocompatibility, good biomechanical strength and stiffness, and good radiopacity for the fluoroscopy guided procedures. PMMA and new filler materials (calcium phosphate cement, calcium sulfate cement, composite materials) are now available for clinical use. In this review paper, we will focus on the issues and characteristics of these filler materials.