Dentistry restorative materials

The largest application of radiation-cured adhesives is for dental procedures (see Adhesion in dentistry restorative materials). Originally UV curable, these have given way to... 

Adhesion in dentistry restorative materials M SHERRIFF Polymers as filling materials... 

There have been numerous reports of possible allergic reactions to mercury and mercury salts and to the mercury, silver and copper in dental amalgam as well as to amalgam corrosion products Studies of the release of mercury by amalgams into distilled water, saline and artificial saliva tend to be conflicting and contradictory but, overall, the data indicate that mercury release drops with time due to film formation and is less than the acceptable daily intake for mercury in food . Further, while metallic mercury can sensitise, sensitisation of patients to mercury by dental amalgam appears to be a rare occurrence. Nevertheless, there is a growing trend to develop polymer-based posterior restorative materials in order to eliminate the use of mercury in dentistry. 

Welsh, E. L. Hembree, J. H. (1985). Microleakage of the gingival wall with four class V anterior restorative materials. Journal of Prosthetic Dentistry, 54, 370-2. 

Hannah, C. M. Smith, D. C. (1971). Tensile strengths of selected dental restorative materials. Journal of Prosthetic Dentistry, 26, 314-23. 

Matsui, A., Buonocore, M. G., Sayegh, F. Yamaki, M. (1967). Reactions to implants of conventional and new dental restorative materials. Journal of Dentistry for Children, 34, 316-22. 

Trivedi, S. C. Talim, S. T. (1973). The response of human gingiva to restorative materials. Journal of Prosthetic Dentistry, 19, 73-80. 

Jendresen, M. D. Phillips, R. W. (1969). A comparative study of four zinc oxide eugenol formulations as restorative materials. Part II. Journal of Prosthetic Dentistry, 21, 300-9. 

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. 

The most common dental polymers, used for prosthetic purposes and restorative dentistry (filling material), are polymethacrylates.1514 The polymerization process performed directly in the dental cavity has to meet strict demands the reaction must be fast at a temperature below 50 °C and it must avoid the formation of a toxic product. These requirements can be fulfilled by UV curing. For example, a mixture of camphorquinone (586), a chromophore (photoinitiator) with an absorption maximum at 468 nm and an amine 587 as a co-initiator (see also Scheme 6.100), initiates a radical polymerization reaction of the acrylate monomer 588 upon photolysis using a conventional blue lamp or laser (Scheme 6.285). 

In the realm of dentistry, restoration and protection of tooth enamel are of great importance in operative and conservative dentistry. Yamamoto et al. (2013) used PLD to create a freestanding flexible double-layered sheet composed of a 4 pm thin hydroxyapatite (HAp) layer coated with a 0.5 pm thin TCP layer. The adhesive strength between the HAp/TCP sheet and enamel was 5.7 MPa, decidedly higher than that between the monolayered HAp sheet and enamel (1.9 MPa). Electron microscopical observation revealed that the HAp/TCP sheet was largely fused with the enamel. Therefore, the double-layered HAp/TCP sheet can be used as a material to promote the repair of tooth eruption and to maintain healthy dentine. 

A., and Noack, M.J. (2014) Restorative dentistry and restorative materials over the next 20 years a Delphi survey. Dent. Mater., 30 (4), 442-418. 

Titanium-aluminum-niobium alloys have been developed for biocompatible, high-strength surgical implants (Semlitsch et al. 1985), while metal-resin composites containing niobium as filler have potential use as restorative materials in dentistry (Misra and Bowen 1977). The metal possesses superior superconductive properties in strong magnetic fields, which may be... 

The essential features of the two basic types of restorative material are given in Table 2.1. From this, it can be seen that each type has its own advantages and disadvantages. In terms of overall properties, modem composite resins appear to be favoured, and there is evidence that these materials are the ones used in the majority of aesthetic repairs in dentistry, particularly in adults. However, as the development of the polyacid-modified composite resins (compomers) shows, these materials are far from perfect, and there is unquestionably scope to enhance their properties. Glass-ionomer cements have properties that would seem to indicate the direction in which improvements could be made, despite the technical difficulties in doing so. 

International Organisation for Standardisation, Dentistry Polymer-Based Restorative Materials, ISO 4029, ISO, Geneva, Switzerland, 2009. 

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. 

Resin-modified glass-ionomers have more or less the same clinical applications as conventional glass-ionomers, with the possible exception of their use in the ART technique [94]. Thus, they have been widely used in Class I, Class H, Class HI and Class V restorations as the full restorative material. They have also been used as liners and bases and, despite the issues with biocompatibility, have found particular appUcation in children s dentistry [94]. 

After surface preparation, the restorative material is bonded to the tooth structure with auto-polymerizing adhesive resin. One prerequisite for dental adhesives is an ability to cure in the mouth that is why methaciylate-based polymer materials are used in dentistry. Initiation systems are BPO-f amine or TBB (201). Monomers used are MMA or bifunctional methacrylate monomers. The needed optical opacity (215,216) is achieved by various inorganic and metal compoimds incorporated into the formulations. 

Barret and Hench (1980) and Wu (1985) improved the chemical durability of lithium disilicate glass-ceramics to a significant extent by incorporating additions such as AiPj and K2O to the stoichiometric base glass. The objective of improving the chemical durability of this glass-ceramic was to render the material suitable for use as a biomaterial in human medicine and, in particular, as a restorative material in dentistry. 

Adhesion is becoming more and more important in many situations in dentistry. Effective adhesion retains restorative dental materials at proper positions of tooth structure, solves the problem of leakage around restorations, and, consequently, improves their performances. Recently, adhesion of ceramic restorative materials is attracting increasingly more attention, as ceramics are highly desirable for esthetic restoration in terms of toothlike appearance, inertness, and durability. Because of their brittle nature, however, the ceramics must be bonded steadily to tooth structure to assure endurance under continual occlusal load for practical uses as dental materials. 

In view of the potential importance of ceramic materials for esthetic dentistry, we have focused our attention on the development of high-performance dental adhesives for calcium metaphosphate ceramic as a novel restoration material. The calcium metaphosphate ceramic is characterized by considerable similarities of the appearance, composition, and physical... 

Modern resin-based restorative materials used in stomatology originated with the invention of the so-called Bowen s monomer and the introduction of composites [142]. This monomer is known as BisGMA, a label easier to use than chemical name of 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)-phenyl]propane.Today, both unfilled and composite resins are widely employed in dentistry—as binding agents, pit and fissure sealants, direct filling materials, orthodontic adhesives, and resin cements [143]. 

Abstract Adhesive techniques and materials are being used increasingly in clinical dentistry, and they are reviewed in the present chapter. Broadly speaking, there are two types of tooth-colored restorative material, the so-called composite resins and the glass-ionomer cements. There are, though, variations on these basic types, as explained in the chapter. In addition, there is the zinc polycarboxylate cement, which was the first adhesive dental restorative material to be developed, and it retains a niche in modem clinical practice. 

Zinc polycarboxylate was the first of the adhesive dental restorative materials to be described. It was invented by Smith (1968) who reported that it was fabricated from aqueous polyacrylic acid and deactivated zinc oxide, and that it had excellent adhesion to both dentin and enamel. It was also found to have other desirable properties. For example, it set rapidly with minimal shrinkage, it was bland toward the soft tissues of the mouth, and it was almost completely insoluble in saliva (Smith 1968). Zinc polycarboxylate cement can thus be considered a major development in the field of adhesive dentistry. Typical properties of zinc polycarboxylate cement are shown in Table 56.4. 

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