Applications bone cements

This abundantly available polymer has been investigated for various biomedical applications such as scaffolds for bone tissue engineering applications, bone cements, and as drug delivery systems. Starch based microparticles and fiber mesh scaffolds are used as carriers for osteoblasts, bone marrow stromal cells... 

Staining Applications Bone cement cytoplasm horny layer cell large intestine nucleic acids skin stratum corneum cell tissues hairs ... 

Only two of these materials are of practical importance the zinc polycarboxylate cement of Smith (1968) and the glass-ionomer cement of Wilson Kent (1971). Both are used in dental applications and both have been used as bone cements. The glass-ionomer cement is, perhaps, the most versatile of all AB cements. It has many applications in dentistry a... 

The glass polyalkenoate cement uniquely combines translucency with the ability to bond to untreated tooth material and bone. Indeed, the only other cement to possess translucency is the dental silicate cement, while the zinc polycarboxylate cement is the only other adhesive cement. It is also an agent for the sustained release of fluoride. For these reasons the glass polyalkenoate cement has many applications in dentistry as well as being a candidate bone cement. Its translucency makes it a favoured material both for the restoration of front teeth and to cement translucent porcelain teeth and veneers. Its adhesive quality reduces and sometimes eliminates the need for the use of the dental drill. The release of fluoride from this cement protects neighbouring tooth material from the ravages of dental decay. New clinical techniques have been devised to exploit the unique characteristics of the material (McLean Wilson, 1977a,b,c Wilson McLean, 1988 Mount, 1990). 

We chose to modify the anhydride monomers with photopolymerizable methacrylate functionalities. Methacrylate-based polymers have a long history in biomedical applications, ranging from photocured dental composites [20] to thermally cured bone cements [21]. Furthermore, photopolymerizations provide many advantages for material handling and processing, including spatial and temporal control of the polymerization and rapid rates at ambient temperatures. Liquid or putty-like monomer/initiator... 

The ultimate success of methyl methacrylate bone cements in surgical arenas depends on its application at an appropriate viscosity. Recent studies have raised concerns that the long-term stability of bone cements may be compromised by the empirical way in which the setting of samples is determined [6]. The literature from one manufacturer states that, in addition to the concentration effects one would expect in a biphasic free-radical... 

T. Yamamuro, T. Nakamura, H. lida, K. Kawanabe, Y. Matsuda, K. Ido, J. Tamura, Y. Seneba, Development of bioactive bone cement and its clinical applications. Biomaterials 19 (1998) 1479-1482. 

Another example of composites in biomedical applications is graphite-fiber-reinforced bone cement. Self-curing poly(methyl methacrylate), PMMA, is used extensively as a bone cement in orthopedic surgery for fixation of endoprostheses... 

A. S. Wagh and C. Primus, Method and product for phospho-silicate slurry for use in dentistry and related bone cements, US Patent Application, no. 60/493,958, 2003. 

Major polymer applications optical fibers, dials, optical components, household items, car rear lights, artificial stones (filled products) for injection molded bath sinks, and kitchen worktops, bone cement, composites, medical applications (e.g. bone cement)... 

Typical concentration range generally - 20-30 wt% carbon black - 5-30 wt% glass powder in bone cement - 30-80 wt% titanium fiber - 1.5%, aluminum or nickel for conductive applications - 20 vol%... 

Most material studies reported in medical journals are of interest to those involved in mainstream plastic applications. Some medical plastics must perform under constant water immersion. It was reported that absorption of 1 % water reduces the fatigue life of PMMA by a factor of four, since bone cement can only be replaced by a surgical operation such a performance is clearly unacceptable. The use of silane to treat the hydroxyapatite filler in this material reduced water uptake. The water uptake increased with increased concentration of hydroxyapatite. In applications, such as dental fillings, increased water uptake is considered helpful since it compensates for the loss of volume due to shrinkage of the filling during curing. 

The last method to be discussed, which is used to form polymer/ceramic composites by electrospinning, is extremely different to the methods previously described, but worth mentioning. Zuo et al. [129] used a method to create a composite scaffold that is actually the reverse of what most people are doing. Instead of mineralizing the nanofibers, Zuo et al. actually incorporated electrospun polymer nanofibers into a ceramic bone cement in order to form a composite scaffold. It was found that by incorporating electrospun nanofibers into the cement, the scaffold became less brittle and actually behaved similarly to that of a ductile material because of the fibers. Composite scaffolds with different polymers and fiber diameters were then tested in order to determine which scaffold demonstrated the most ideal mechanical properties. However, no cell studies were conducted and this method would most likely be used for a bone substitute instead of for bone regeneration applications. 

Cement is a binder that sets and hardens by itself or binds other materials together. The most widely known application of cements is in construction a second one is the area of bone cements. Cements used in construction are characterized as hydraulic or nonhydraulic and mostly for the production of mortars and concrete. Hydraulic cements set and harden after combining with water. Most construction cements are hydraulic and based on Portland cement, which consists of calcium silicates (at least 2/3 by weight). Nonhydraulic cements include the use of nonhydraulic materials such as lime and gypsum plasters. Bone cements and bone cement composites refer to compounds that have a polymer matrix with a dispersed phase of particles. For instance, polymethylmethacrylate (PMMA) is reinforced with barium sulphate crystals (for radio-opacity) or with hydroxyapatite... 

It has exceptionally good optical properties its transparency has made it a popular substitute for glass in apphcations where breakage must be avoided (plexiglass). It has a variety of industrial uses including automotive parts and glazings. PMMA was the first implanted synthetic polymeric biomaterial it was used as a hip prosthesis in 1947 (see USP XVIII, The Pharmacopia of the USA, (18th Revision), US Pharmacopoeia Convention, Inc., Rockville, MD, 1 September 1980). PMMA is currently used in orthopedic applications, as bone cement, and in intraocular lenses. 

Bone cements are vital to use in hip joint operations as a glue. It is polymerised in situ, from the monomer, when catalysts (usually benzoyl peroxide) and additives are all mixed together at the place of application (in the body, between the bones to be glued). Besides the slight increase of temperature locally (due to the exothermic polymerisation reaction), which is a discomfort certainly, there will be danger from remnants of monomer that are left, after the reaction, at the site of application in the body [23]. 

Medical applications Prosthetics, fibrous bone cement... 

Though it is a hard brittle material, PMMA have an extensive record in medical applications as dental fillings, intraocular lens, and bone cements since the 1940s (Figure 18.1c). This... 

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