Biomaterials for Dental Applications

Title Polymerizable Compositions with Acylgermanes as Initiators 

Patent Application Material Patentability Anticipated Issuing Date  

Research Focus Synthesis of mono- and bisacylgermane derivatives useful as polymerization initiators in dental cements. 

Originality Acylgermane derivatives as polymerization initiatiois have not been 

Observations The commercial Norrish Type I photoinitiator Irgacure -819, bis(2,4,6- 

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Biomaterials for Dental Applications a. Acylgermane-containing polymers... 

The only wide-range application and commercialisation area of fluoride-containing biomaterials concern ionomer glasses for dental applications. The improved biological effect of these compounds is related to a slow release of active fluoride ions in biological fluids and the direct effect of fluoride ions on mineralised biological tissues. 

Gheysen G., Ducheyne R, Hench L.L., and de Meester P. 1983. Bioglass composites a potential material for dental application. Biomaterials 4 81-84. 

These desired applications determine the main requirements to be fiilfilled in the development of glass-ceramics for dental applications. The main objective is to produce a new biomaterial, the properties of which correspond to those of natural teeth. The most important properties are mechanical properties, biochemical compatibility with the oral environment, and a degree of translucency, shade, opalescence, and fluorescence similar to that of natural teeth. An abrasion resistance similar to that of natural teeth must also be achieved. The new biomaterial must demonstrate higher chemical durability than natural teeth, to prevent it from being susceptible to decay. 

One of the most useful zirconium-based materials is zirconia, Zr02-Zirconia may be found in a variety of phases (i.e., cubic, orthorhombic), exhibits exceptional resistance to fracturing, and is highly chemically inert. Zirconia is an excellent refractory material and has found many applications in high-heat environments. The hardness and high chemical stability of zirconia make this material well suited for dental applications [1,2]. Ceramic biomaterials based on zirconia have gained popularity in a variety of appHcations [3], such as knee and hip replacements, and are noted for their durability [4]. Cubic zirconia is also used in jewelry. 

Given that the structural building blocks of the tooth are essentially composed of polymeric constituents, it is no surprise that the progress of dentistry and dental biomaterials would seek to approximate the polymeric composition of the natural tooth [7], Interestingly, however, it was not until the mid 1900s that polymeric materials emerged as an alternative material for dental applications [8],... 

The toxicity of LCER nanocomposite is lower than that of nanocomposite contains no LCER and commercial dental restorative materials by both MTT and LDH tests (Fig. 19.8). Therefore, the LCER nanocomposite is a good biomaterial for medical applications. 

Ordering behaviors and age-hardening in experimental AnCn-Zn pseudobinary alloys for dental applications, S. H. Seol, T. Shiraishi, Y. Tanaka, E. Mima, K. Hisatsnne, and H. I. Kim, Biomaterials, 2002, 23(24), 4873-9. 

In dentistry, silicones are primarily used as dental-impression materials where chemical- and bioinertness are critical, and, thus, thoroughly evaluated.546 The development of a method for the detection of antibodies to silicones has been reviewed,547 as the search for novel silicone biomaterials continues. Thus, aromatic polyamide-silicone resins have been reviewed as a new class of biomaterials.548 In a short review, the comparison of silicones with their major competitor in biomaterials, polyurethanes, has been conducted.549 But silicones are also used in the modification of polyurethanes and other polymers via co-polymerization, formation of IPNs, blending, or functionalization by grafting, affecting both bulk and surface characteristics of the materials, as discussed in the recent reviews.550-552 A number of papers deal specifically with surface modification of silicones for medical applications, as described in a recent reference.555 The role of silicones in biodegradable polyurethane co-polymers,554 and in other hydrolytically degradable co-polymers,555 was recently studied. 

This contribution will provide a review of polylectrolytes as biomaterials, with emphasis on recent developments. The first section will provide an overview of methods of synthesizing polyelectrolytes in the structures that are most commonly employed for biomedical applications linear polymers, crosslinked networks, and polymer grafts. In the remaining sections, the salient features of polyelectrolyte thermodynamics and the applications of polyelectrolytes for dental adhesives and restoratives, controlled release devices, polymeric drugs, prodrugs, or adjuvants, and biocompatibilizers will be discussed. These topics have been reviewed in the past, therefore previous reviews are cited and only the recent developments are considered here. 

Following these two surveys, we conducted a literature review based upon Ceramic Abstracts for the years 1988-2002. The results are summarized in Table 2.1. The results presented in Table 2.1 indicate that there has been a significant increase in the literature on CBPCs in recent years. The major thrust of the research has been in biomaterials and dental cements. Though small in number, there have been several articles in structural materials applications, which also include oil well cements. Interest in conventional refractory materials has continued, and as expected, all the applications have been supported by research in materials structure and properties of the CBPCs. 

Other biomedical applications of polymers include sustained and controlled drug delivery formulations for implantation, transdermal and trans-cornealuses, intrauterine devices, etc. (6, 7). Major developments have been reported recently on the use of biomaterials for skin replacement (8), reconstruction of vocal cords (9), ophthalmic applications such as therapeutic contact lenses, artificial corneas, intraocular lenses, and vitreous implants (10), craniofacial, maxillofacial, and related replacements in reconstructive surgery (I), and neurostimulating and other electrical-stimulating electrodes (I). Orthopedic applications include artificial tendons (II), prostheses, long bone repair, and articular cartilage replacement (I). Finally, dental materials and implants (12,13) are also often considered as biomaterials. 

Polymers are the most versatile class of biomaterials, being extensively used in biomedical applications such as contact lenses, pharmaceutical vehicles, implantation, artificial organs, tissue engineering, medical devices, prostheses, and dental materials [1-3]. This is all due to the unique properties of polymers that created an entirely new concept when originally proposed as biomaterials. For the first time, a material performing a structural application was designed to be completely resorbed and become weaker over time. This concept was applied for the... 

Table 19.1 summarizes some of the existing usage of polymeric biomaterials in a variety of implantable prostheses for cardiovascular, orthopedic, ophthalmologic, and dental applications. 

In recent years, dental research has been focused on dental implants and artificial teeth rooted in a patient s jaw allowing for a permanent denture, as alternatives to bridges or false teeth. A wide array of materials including polymers such as UHMWPE, PTFE, and PET have been used in many types of existing dental implants [54,119]. Porous polymeric surfaces are now designed to facilitate bone integration [54], Other dental applications of polymeric biomaterials have been for the development of a dental bridge, meant as a partial denture or false teeth. In extreme cases, removable dentures fabricated from PMMA are used to overcome the loss of all teeth [203]. 

A further direction of advancement was originated by the progress being made in research and surgery and by the demand for materials with special properties for special applications. For these cases the materials, which are often composite materials, had to be tailored to the intended application. One example is the development of the alloy TiTa30 which in its thermal expansion coefficient is very similar to alumina and can therefore be crackfree bonded with the ceramic. This material is used as a dental implant. The metallic biomaterial which can resist bending stresses is inserted into the jaw. The upper part of the implant consisting of alumina, which shows a smaller deposition of plaque than the metallic materials. 

A wide range of polyphosphazenes have been used for a number of biomedical applications. Examples are inert biomaterials for cardiovascular and dental uses, bioerodible and water soluble polymers for controlled drug delivery applications (Allcock et al, 1990). 

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