Development and Characterization of Acrylic Based Bone Cements

Bone tissue engineering has emerged as a multidisciplinary field in recent times with an aim to expedite the process of regeneration of damaged or diseased tissues. This study is an attempt to fabricate and characterize Tricalcium Phosphate (TCP) and Chitosan incorporated Polymethylmethacrylate (PMMA) based bone cement. In total two experimental PMMA based bone cements were fabricated that were differentiated by presence and absence of Chitosan. In both groups (10 and 30 wt.%) TCP were incorporated into Methyl methacrylate (MMA) monomer. PMMA was used as a control. The physical, mechanical and thermal properties of the composites were assessed. Morphological changes of PMMA after the introduction of TCP and Chitosan were observed by means of X-ray diffraction (XRD). Major peak shifts in Fourier transform Infrared spectroscopy (FTIR) spectra demonstrated the strong bonding of PMMA with incorporated materials. PMMA incorporated with 10% TCP showed the maximum wettability in absence of Chitosan. Hardness of the tested specimens decreased with increasing content of TCP which in turns enhanced ductility. It was also observed that neither of the samples showed significant degradation. The incorporation of additives enhance the physical and chemical properties of PMMA as bone cement.

Brushite bone cement containing polyethylene glycol for bone regeneration

BACKGROUND: Bone cements aid in bone regeneration; however, if the handling time is not well established for the material to harden, complications may arise. OBJECTIVE: This work investigates the effect of using polyethylene glycol (PEG) and characterize it in brushite bone cement in order to obtain desirable handling times as well as its regeneration in vivo to analyse if addition of this polymer may significantly modify its properties. METHODS: PEG 4000 was synthesised with wollastonite by phosphorization reaction in order to form brushite which was further cured by oven drying. They were further characterised and tested in vivo as tibial bone defect model using rabbits. RESULTS: Addition of PEG exhibited handling times of 60 min with a low increase in temperature when curing. Brushite phase of ∼71% was obtained after cement hardening with good compressive strength (25 MPa) and decent values of porosity (33%). In vivo presented that, at 40 days postoperatively, accelerated bone neoformation with partial consolidation at 30 days and total after 60 days when using bone cement. CONCLUSIONS: Addition of PEG does not disrupt the beneficial properties of the bone cement and can be a potential alternative for control the time-temperature profile of hardening these materials.

Additives Imparting Antimicrobial Properties to Acrylic Bone Cements

PMMA bone cements are mainly used to fix implanted prostheses and are introduced as a fluid mixture, which hardens over time. The problem of infected prosthesis could be solved due to the development of some new antibacterial bone cements. In this paper, we show the results obtained to develop four different modified PMMA bone cements by using antimicrobial additives, such as gentamicin, peppermint oil incorporated in hydroxyapatite, and silver nanoparticles incorporated in a ceramic glass matrix (2 and 4%). The structure and morphology of the modified bone cements were investigated by SEM and EDS. We perform experimental measurements on wettability, hydration degree, and degradation degree after immersion in simulated body fluid. The cytotoxicity was evaluated by MTT assay using the human MG-63 cell line. Antimicrobial properties were checked against standard strains Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The addition of antimicrobial agents did not significantly affect the hydration and degradation degree. In terms of biocompatibility assessed by the MTT test, all experimental PMMA bone cements are biocompatible. The performance of bone cements with peppermint essential oil and silver nanoparticles against these two pathogens suggests that these antibacterial additives look promising to be used in clinical practice against bacterial infection.

PMMA Bone Cements Modified with Silane-Treated and PMMA-Grafted Hydroxyapatite Nanocrystals: Preparation and Characterization

In this study, vinyltrimethoxysilane-treated hydroxyapatite (vHAP) and PMMA-grafted HAP (gHAP) were successfully prepared from original HAP (oHAP). Three kinds of HAP (oHAP, vHAP and g HAP) were used as additives for the preparation of three groups of HAP-modified PMMA bone cements (oHAP-BC, vHAP-BC and gHAP-BC). The setting, bending and compression properties of the bone cements were conducted according to ISO 5833:2002. The obtained results showed that the maximum temperature while curing the HAP-modified bone cements (HAP-BCs) decreased from 64.9 to 60.8 °C and the setting time increased from 8.1 to 14.0 min, respectively, with increasing HAP loading from 0 to 15 wt.%. The vHAP-BC and gHAP-BC groups exhibited higher mechanical properties than the required values in ISO 5833. Electron microscopy images showed that the vHAP and gHAP nanoparticles were dispersed better in the polymerized PMMA matrix than the oHAP nanoparticles. FTIR analysis indicated the polar interaction between the PO4 groups of the HAP nanoparticles and the ester groups of the polymerized PMMA matrix. Thermal gravimetric analysis indicated that mixtures of ZrO2/HAPs were not able to significantly improve the thermal stability of the HAP-BCs. DSC diagrams showed that the incorporation of gHAP to PMMA bone cement with loadings lower than 10 wt.% can increase Tg by about 2.4 °C.

Comparative evaluation of polymethylmethacrylate and composite bone cements. Review of the experimental studies results

Current article is a review of experimental studies of different bone cements types and their combinations. Providing of bone fragments stable fixation at osteosynthesis in cases of difficult multifragmental fractures, arthroplasties and other implants using especially in the osteoporosis conditions is a main task of orthopaedic surgery procedures. Polymethylmethacrylate (PMMA) is the first material that is answered to these requirements. The evolution of bone cements resulted in creation of a new composite substance — combination of PMMA and β-threecalciumphosfates (β-TCPh). Combination of these two components allowed to provide high bioabsorbal, osteoconductive and osteointegrative properties along with sufficient durability. In the analyzed works the properties of composite cement CalCemex were evaluated in vivo experiment. It was found that in the case of PMMA penetration of bone tissue into the polymer structure did not occur. Under the conditions of using bone cement with β-TCF admixture, the formation of bone tissue was observed not only on the surface of the implant, but also in the external and internal pores. It is the presence of pores in CalCemex that the authors explain the possibility of penetration of cellular elements, blood vessels and bone formation. Moreover, β-TCPh is included into this material and it is bioresorbed by osteoclasts. This leads to the release of calcium and phosphorus ions and, consequently, simplifies the attachment of the newly formed bone to the bone cement. We assume that composite cement like CalCemex type is a promising material for the treatment of various types of fractures and replacement of bone defects. It should be mentioned that research in this area is ongoing and intensive work is underway to synthesize and study the results of clinical application of composite bone cements with maximum bioactive properties that will not only strengthen bone tissue but also perform osteointegrative function. Key words. Bone cement, polymethylmethacrylate, β-threecalciumphosfates, experiment.

Synthesis techniques, characterization and mechanical properties of natural derived hydroxyapatite scaffolds for bone implants: a review

Hydroxyapatite (HAp) with good mechanical properties is a promising material meant for a number of useful bids in dentistry and orthopedic for biomedical engineering applications for drug delivery, bone defect fillers, bone cements, etc. In this paper, a comprehensive review has been done, by reviewing different literatures related to synthesis techniques, mechanical properties and property testing, method of calcination and characterization of hydroxyapatite which are product of catfish and bovine bones. The discussion is in relations of the obligatory features vital to attain the best properties for the envisioned bid of bone graft. The process approaches that are capable of fabricating the essential microstructure and the ways to advance the mechanical properties of natural mined HAp are reviewed. The standard values for tensile strength were found to be within the range of 40–300 MPa, compressive strength was 400–900 MPa, while Elastic modulus was 80–120 GPa and fracture toughness was 0.6–1 MPa m1/2 (Ramesh et al. in Ceram Int 44(9):10525–10530, 2018; Landi et al. in J Eur Ceram Soc 20(14–15):2377–2387, 2000; Munar et al. in Dent Mater J 25(1):51–58, 2006). Also, the porosity range was 70–85% (Yang et al. in Am Ceram Soc Bull 89(2):24–32, 2010), density is 3.16 g/cm3 and relative density is 95–99.5% (Ramesh et al. 2018; Landi et al. 2000; Munar et al. 2006). The literature revealed that CaP ratio varies in relation to the source and sintering temperature. For example, for bovine bone, a CaP ratio of 1.7 (Mezahi et al. in J Therm Anal Calorim 95(1):21–29, 2009) and 1.65 (Barakat et al. in J Mater Process Technol 209(7):3408–3415, 2009) was obtained at 1100 °C and 750 °C respectively. Basic understanding on the effect of adding foreign material as a strengthening agent to the mechanical properties of HAp is ground factor for the development of new biomaterial (Natural hydroxyapatite, NHAp). Therefore, it is inferred that upon careful combination of main parameters such as compaction pressures, sintering temperatures, and sintering dwell times for production natural HAp (NHAp), mechanical properties can be enhanced. Graphic abstract

Experimental study of the mechanical properties of Palacos bone cements

Background. Currently, bone cements are widely used in orthopedics. The range of prescriptions for bone cement use is very large, and requires different qualities depending on the purpose. Therefore, researchers are forced to conduct their own invetigations to study the mechanical properties of bone cements. The purpose was to determine in the experiment the value of an elastic modulus and ultimate strength of Palacos bone cements for further use in mathematical models of osteosynthesis and arthroplasty. Materials and methods. Samples of two brands of cement, Palacos R and Palacos fast, were examined. Samples with a diameter of 5 mm and a length of 10 mm were made from each type of cement. The study was carried out 2 hours and 2 days after polymerization. At each stage, 10 cement samples of each type were tested for compression. Results. After 2 hours of polymerization, the Palacos fast samples had a statistically significant advantage in terms of the tensile strength, which was 105.77 ± 3.19 MPa, over the Palacos R — 87.24 ± 3.70 MPa. The higher elastic modulus for Palacos fast samples — 2,942.50 ± 99.67 MPa compared to Palacos R — 82,542.40 ± 65.55 MPa turned out to be statistically significant. Two days after fabrication, the strength characteristics of bone cements changed upward. Thus, the ultimate strength of Palacos fast samples was determined within 116.39 ± 2.85 MPa, which is statistically significant higher than for Palacos R samples for which this indicator was within 95.58 ± 4.53 MPa. Similar tendencies were characteristic of an elastic modulus, which amounted to 3,048.93 ± 108.70 MPa for Palacos fast and 2,642.90 ± 22.93 MPa — for Palacos R samples. The value of the elastic modulus for both brands of bone cement has a statistically significant tendency to increase. On average, an elastic modulus for Palacos R cement increased by 4.0 ± 2.6 %, for Palacos fast samples — by 3.5 ± 1.4 %. Conclusions. Palacos R bone cement by the end of the polymerization process has an elastic modulus of 2,542.40 ± 65.55 MPa and a tensile strength of 87.24 ± 3.70 MPa, which is statistically significant lower (p = 0.001) than thereof Palacos fast cement (2,942.50 ± ± 99.67 MPa and 105.77 ± 3.19 MPa, respectively). The indicators of the tensile strength and elastic modulus of the samples of bone cement of both studied brands have a statistically significant (p = 0.001) tendency to increase within 2 days, on average by 9.6 ± 10.1 % and 3.5 ± 4.0 %, respectively. The obtained elastic modulus and ultimate strength of Palacos R and Palacos fast bone cements can be used for mathematical modeling of various types of arthroplasty.

Preparation, Structural Characterization, and Biomedical Applications of Gypsum-Based Nanocomposite Bone Cements

Hard tissues are natural nanocomposites comprising collagen nanofibers that are interlocked with hydroxyapatite (HAp) nanocrystallites. This mechanical interlocking at the nanoscale provides the unique properties of hard tissues (bone and teeth). Upon fracture, cements are usually used for treatment of simple fractures or as an adhesive for the treatment of complicated fractures that require the use of metallic implants. Most of the commercially available bone cements are polymer-based, and lack the required bioactivity for a successful cementation. Besides calcium phosphate cements, gypsum is one of the early recognized and used biomaterials as a basi for a self-setting cementation. It is based on the controlled hydration of plaster of Paris at room temperature and its subsequent conversion to a self-setting solid gypsum product. In our work, we have taken this process further towards the development of a set of nanocomposites that have enhanced bioactivity and mechanical properties. This chapter will outline the formation, characterization, and properties of gypsum-based nanocomposites for bone cement applications. These modified cements can be formulated at room temperature and have been shown to possess a high degree of bioactivity, and are considered potential candidates for bone fracture and defect treatment.