Dentinal dental caries

Armstrong WG (1964) Modifications of the properties and compositon of the dentin matrix caused by dental caries. Adv Oral Biol 1, 309-332. 

Fluorine is an essential element involved in several enzymatic reactions in various organs, it is present as a trace element in bone mineral, dentine and tooth enamel and is considered as one of the most efficient elements for the prophylaxis and treatment of dental caries. In addition to their direct effect on cell biology, fluoride ions can also modify the physico-chemical properties of materials (solubility, structure and microstructure, surface properties), resulting in indirect biological effects. The biological and physico-chemical roles of fluoride ions are the main reasons for their incorporation in biomaterials, with a pre-eminence for the biological role and often both in conjunction. This chapter focuses on fluoridated bioceramics and related materials, including cements. The specific role of fluorinated polymers and molecules will not be reviewed here. 

The most common oral condition and dental emergency is dental caries, which is a destructive disease of the hard tissues of the teeth due to bacterial infection with Streptococcus mutans and other bacteria. It is characterized by destruction of enamel and dentine. Dental decay presents as opaque white areas of enamel with grey undertones and in more advanced cases, brownish discoloured cavitations. Dental caries is initially asymptomatic and pain does not occur until the decay impinges on the pulp, and an inflammation develops. Treatment of caries involves removal of the softened and infected hard tissues, sealing of exposed dentines and restoration of the lost tooth structure with porcelain, silver, amalgam, composite plastic, gold etc. 

Early dental caries (incipient lesions) are non-cavitated and limited to the outer enamel surface. Clinically, these lesions are identified as visible white spots when the tooth is air-dried (Fig. 11.1). The incipient lesion is known as a subsurface lesion since the surface appears intact. However, histological investigations have shown that below the surface, there are zones that vary in porosity (voids from mineral loss) as well as biochemical composition (e.g. fluoride, water and carbonate content) [29]. The enamel caries can vary from a depth of 100-250 J.m (for incipient caries) to entirely through the enamel ( 1.5mm deep), at which point the cavitated lesion has extended into the underlying dentin [35]. The diagnostic challenge remains early caries detection and the focus has been on caries lesions that form on the tooth crown affecting the enamel. The remainder of the discussion will therefore concentrate on enamel caries. 

Notable examples of enzyme inhibitors include the many antibiotics that block certain vital funetions in baeteria, but which in controlled doses are not toxic to humans (although there are some antibiotics that are too toxic to use, including some that even kill eaneer eells). Bacterial cells, called prokaryotes, are fortuitously different from mammalian cells, called eukaryotes, and respond differently. The use of fluorides to prevent dental caries is anoth example, the fluorides acting as inhibitors for certain critical enzymes in oral bactraia, as well as facilitating a beneflcial interaction with the dentine at the tooth surfaces. (And, as sometimes warned, if ingested these fluorides can also act as inhibitors for other enzymes within the body.)... 

Several different types of dental caries have been described by clinicians. Specifically these are smooth-surface caries, pit and fissure caries, enamel caries, dentinal caries, secondary caries, early childhood caries and root caries [12], All occur by the same essential mechanism, as described above, and all arise as a consequence of a disturbance to the demineralization-remineralization balance. Attack by organic acids produced by bacteria in the plaque favours demineralization, but the natural remineralization processes of the mouth can reverse this. Certain dietary and hygiene behaviours as well as clinical treatments can enhance this natural remineralization provided they occur early enough in the demineralization part of the process. For example, complexes of casein phosphopeptide with amorphous calcium phosphate have been shown in various studies to be capable of enhancing the remineralization step under certain conditions and in specific groups of individuals [16,17]. These are now available commercially as an anticaries treatment for patients. 

As dental caries progresses, it reaches the dentine and it moves much more rapidly through this tissue than through the enamel [35,36]. This substantially alters the... 

Derise, N.L., Ritchey, S.J. and Furr, A.K. (1974) Mineral composition of normal human enamel and dentin and the relation of composition to dental caries I Macrominerals and comparison of methods of analyses. J. Dental Res., 53(4), 847-852. 

The human mouth is a unique organ that facilitates oral intake and speech production [159]. It is a site of multiple pathologies including dental caries, periodontitis, dentin... 

Keywords Resin composite Dental adhesion Bonding Caries Dentin Dental polymer... 

Great emphasis has been given to the development of fluoride releasing materials, however, the direct antibacterial effect of dental materials is another important property as the inactivation of bacteria is a direct way to eradicate the cause of dental caries. Many attempts for developing dentin-bonding systems and restorative materials presenting antibacterial activity have been performed [55-62]. 

Other Systemic Effects. Radiation damage to dental tissue, or perhaps to its blood supply, initiates extensive resorption of the dentine, especially at the gum line. These radiation-induced caries weaken teeth and cause them to fracture easily. Such tooth breakage has been reported in 12% (27/218) of patients injected with radium-224 as children (20 years old and younger) and by 2% (17/681) of patients injected as adults (21 years old and older). The highest incidence occurred in adolescents injected at 16 to 20 years of age (15/61 or 25%). Combining results from all age groups, the incidence of tooth fracture increased significantly with dose (p=0.01) (Sonnabend et al. 1986). 

Eugenol has been used since the nineteenth century as a flavoring agent in a variety of foods and pharmaceutical products. It has found use as a mild rubefacient in dentifrices, and as an obtundent for hypersensitive dentine, caries, or exposed pulp. Additional uses are in dental cement preparations, analgesics and anesthetics, and temporary dental filling when mixed with zinc oxide. The substance is also used in the perfumery or flavor industries, and also as insect attractant [1, 3, 4]. 

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