Dental aesthetics

Ahmad (2005). Antoior dental aesthetic Facial perspective, Br Dent... 

Aesthetic dental ceramics are essentially glass-matrix materials with varying volume fractions of crystalline fillers. Crystalline fillers are used in the glass matrix both for dispersion strengthening, usually at volume fractions of 40—70%, and for altering optical properties, usually at low volume fractions. Dental ceramics are generally manufactured from two distinct classes of materials, ie, beneficiated feldspathic minerals and glass—ceramics. 

Acrylic Resins. The first synthetic polymer denture material, used throughout much of the 20th century, was based on the discovery of vulcanised mbber in 1839. Other polymers explored for denture and other dental uses have included ceUuloid, phenolformaldehyde resins, and vinyl chloride copolymers. Polystyrene, polycarbonates, polyurethanes, and acryHc resins have also been used for dental polymers. Because of the unique combination of properties, eg, aesthetics and ease of fabrication, acryHc resins based on methyl methacrylate and its polymer and/or copolymers have received the most attention since their introduction in 1937. However, deficiencies include excessive polymerization shrinkage and poor abrasion resistance. Polymers used in dental appHcation should have minimal dimensional changes during and subsequent to polymerization exceUent chemical, physical, and color stabiHty processabiHty and biocompatibiHty and the abiHty to blend with contiguous tissues. 

The glass polyalkenoate cement was originally intended as a substitute for dental silicate cements for the aesthetic restoration of front (anterior) teeth (Wilson Kent, 1972 Knibbs, Plant Pearson, 1986a Osborne Berry, 1986 Wilson McLean, 1988). It is suitable for restoring anterior cavities in low-stress situations, that is when the restoration is completely supported by surrounding tooth material. These cavities occur on the adjacent surfaces of neighbouring teeth (class III cavities) and at the gum line (class V cavities). 

Crisp, S., Abel, G. Wilson, A. D. (1979). The quantitative measurement of the opacity of aesthetic dental materials. Journal of Dental Research, 58, 1585-96. 

McLean, J. W. (1980). Aesthetics in restorative dentistry the challenge for the future. British Dental Journal, 149, 368-72. 

Dental silicate cement was once the most favoured of all anterior (front) tooth filling materials. Indeed, it was the only material available for the important task of aesthetic restoration from the early 1900s to the mid 1950s, when the not very successful simple acrylic resins made their appearance (Phillips, 1975). In the mid sixties there were some 40 brands available (Wilson, 1969) and Wilson et al. (1972) examined some 17 of these. Since that time the use of the cement has declined sharply. It is rarely used and today only two or three major brands are on the market. The reason for this dramatic decline after some 50 years of dominance is closely linked with the coming of modern aesthetic materials the composite resin from the mid 1960s onwards (Bowen, 1962), and the glass-ionomer cement (Wilson Kent, 1971) from the mid 1970s. 

Dental silicate cement is used exclusively for the aesthetic restoration of... 

Dental silicate cement is used for the aesthetic restoration of anterior (front) teeth because it is translucent and so can be made to colour-match tooth enamel. It is prepared by introducing powder into the liquid gradually in order to dissipate heat, although the exotherm is not so great... 

The senior author first became interested in acid-base cements in 1964 when he undertook to examine the deficiencies of the dental silicate cement with a view to improving performance. At that time there was much concern by both dental surgeon and patient at the failure of this aesthetic material which was used to restore front teeth. Indeed, at the time, one correspondent commenting on this problem to a newspaper remarked that although mankind had solved the problem of nuclear energy the same could not be said of the restoration of front teeth. At the time it was supposed that the dental silicate cement was, as its name implied, a silicate cement which set by the formation of silica gel. Structural studies at the Laboratory of the Government Chemist (LGC) soon proved that this view was incorrect and that the cement set by formation of an amorphous aluminium phosphate salt. Thus we became aware of and intrigued by a class of materials that set by an acid-base reaction. It appeared that there was endless scope for the formulation of novel materials based on this concept. And so it proved. 

Compomers are properly called polyacid-modified composite resins and are a group of aesthetic materials chemically similar to the well-established composite resins [266], They were introduced to the dental profession in the early 1990s [267], and were intended to combine the benefits of traditional composite resins and glass-ionomer cements, and their trivial name reflects this, being derived from the names of these two parent materials, the comp coming from composite, and omer from ionomer [268], These materials are now considered a distinct class of dental restorative, with well established uses in clinical restoration, particularly in children s dentistry [269],... 

A.J. Preston, E.A. Agalamany, S.M. Fligham, L.FI. Mair, The recharge of aesthetic dental restorative materials with fluoride in vitro—Two year results. Dent. Mater. 19 (2003) 32-37. 

Dental or enamel fluorosis is an irreversible dose-response effect caused by fluoride ingestion during the pre-eruptive development of teeth. The pre-eruptive maturation of crowns of the anterior permanent teeth, which are of most concern aesthetically, is complete and, together with the risk of fluorosis, is over by the age of 7-8 years [46,47]. After the enamel has completed its pre-eruptive maturation, it is no longer susceptible. Therefore, fluoride intake up to the age of 7-8 years is of most interest. Although it is usually the permanent teeth that are affected, occasionally the deciduous teeth may be also involved. 

Polymers used as dental materials must meet several stringent requirements. Dental restorative materials must be nontoxic, have aesthetic appearance, and good adhesive and mechanical properties. In addition, these materials must exhibit long term stability in the presence of water, enzymes, and various oral fluids, and withstand thermal and load cycles. Finally, a desirable dental restorative materia] should be convenient to work with at the time of application. 

The performance of polyelectrolyte materials is determined by several factors, including the extent to which the dental material adheres to the tooth, cario-static properties of the restoration, pulpal and tissue sensitivity in the vidnity of the restorative material, long-term stability of the dental material, and perhaps most importantly, the aesthetic appeal of the restorative material. Poor adhesion leads to the formation of gaps, which become sites for infection. Biodegradation of the cement can cause increased pulpal and oral-tissue sensitivity, as well as systemic responses. Several recent reviews on the performance of GICs [121,173,230-232] are available, so the subject is only briefly discussed here. 

With more than 200 million dental restorations performed each year, the importance of using a restorative material which is both safe and durable should not be underestimated. Currently, dental amalgam is used in the vast majority of these restorations however, recent scrutiny of mercury levels in dental amalgam and the desire for tooth colored restorations have led to increasing demand for polymeric dental composites. Polymeric composites, generally composed of a multimethacrylate and a ceramic glass filler, have primarily been used for anterior tooth restorations in which color matching is imperative for aesthetic purposes. 

Composite resins allow for color matching, conservative cavity preparation, and simple preparation through intraoral photopolymerization. These advantages have made composites an increasingly popular substitute for amalgam in dental restorations, especially when aesthetics are of concern. In this article, we will focus on the actual process of forming dental composites, the properties of the composites that are formed, and a complete description of the photopolymerization of the multimethacrylates that produce the dental composite. We will only be focusing on the use of polymers as dental restorations. Other dental applications of polymers, e.g. dentures and ionomer cements (reviewed elsewhere by Scranton and Klier) will not be addressed. 

The demand for aesthetic dental restorative materials continues to increase and may be the most important criterion for the promising future of the aesthetic polymeric composite resins. As the physical, mechanical, and wear properties of these materials improve, their use in dentistry will expand. The acid-etching of dental enamel [20] and dentin bonding procedures [21] will allow for conservative cavity preparation and the preservation of healthy tooth structure. 

Polymer eomposites are inereasingly used for dental applications [30], the durability and aesthetic appeal has made them ideal substitutes for the more traditional amalgam fillings. The dental polymer eomposites are principally composed of an organic matrix and a powdered ceramic phase. The organic matrix is composed of an aromatic or urethane dimethacrylate such as 2,2-bis[4-(2-hydroxy-3-methacryloyl propoxy) phenyljpropane (bis-GMA) with... 

Dental Polymers. Every year nearly a half billion dental fillings are done, and over a million dentures are constructed. Most of the materials used in each of these cases are polymeric. In addition, over 300,000 dental implants are made each year with either ceramics or polymers (1). The majority of the dental fillings and dentures are made from various copolymers of methyl methacrylate with other acrylics, although some other polymers, such as polyurethanes, vinyl chloride-vinyl acetate-methacrylate copolymers, vulcanized rubber, and epoxies, have been used to some extent. One major problem is aesthetics—the prosthesis must look natural and not discolor (by photoinduction or staining) to any great extent. 

Dental silicate cements were used as aesthetic repair materials for anterior teeth [7]. Though they lacked the ability to adhere to the tooth, they did have a reasonable match for the appearance of the natural tooth, both in terms of colour and translucency. Nonetheless, they were not entirely satisfactory in clinical service and in particular were susceptible to acid erosion and staining in the mouth [7]. 

A.J. Preston, S.M. Higham, E.A. Agalamanyi, L.H. Mair, Fluoride recharge of aesthetic dental materials, J. Oral RehabU. 26 (1999) 936-940. 

D.C. Watts, A.J. Cash, Analysis of optical transmission by 400-500nm visible light into aesthetic dental biomaterials, J. Dent. 22 (1994) 112-117. 

A.M. Young, S.A. Raffeka, J. A. Hewlett, FTIR investigation of monomer polymerisation and polyacid neutralisation kinetics and mechanisms in various aesthetic dental restorative materials. Biomaterials 25 (2004) 823-833. 

Adhesive dentistry, specifically in association with the use of composite resins, has anerged as an important component of modem restorative dentistry. These are several reasons for this. First, as a result of the research into restorative materials of improved aesthetics, there are now polymeric and also ceramic materials that provide an excellent match for the natural tissue of the tooth. This is complemented by an increasing demand for aesthetic repairs by patients [3,4]. This is part of the trend within the developed world for cosmetic dental treatments, and for cosmetic dentistry to be seen as an acceptable part of the profession. 

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