Caries plaque

Mechanical removal of plaque is the most effective measure against plaque-caused diseases, dental caries, and periodontal diseases. Even before the advent of fluoride treatments, it was assumed that a clean tooth does not decay. A toothbmsh is effective in removing dental plaque and, for those individuals who optimize its use, it usually can adequately control plaque. Despite the proven efficacy of mechanical plaque removal, the amount of patient involvement is such that only about 30% of the population in developed countries and considerably less in undeveloped countries can be expected to adequately remove plaque (1). Hence, supplementary measures such as dentifrices and dental rinses are necessary. 

Active agents vary according to use. For controlling bad breath, 2iac salts, sodium lauryl sulfate, and flavors are used. To destroy oral microorganisms, chlorhexidine, cetylpyridinium chloride [123-03-5] and ben2alkonium chloride [68391-01-5] are valuable. Essential oils, such as thymol [89-83-8] eucalyptol [470-82-6] menthol, and methyl salicylate [119-36-8] reduce plaque-related gingivitis (see Oils, essential). Sodium fluoride aids ia caries coatrol. 

Jenkins, G. N. (1965). The equilibrium between plaque and enamel in relation to dental caries. In Wolstenholme, G. E. W. O Connor, M. (eds.) Caries Resistant Teeth, pp. 192-210. London Churchill. 

Rolla, G. (1977). Effects of fluoride on initiation of plaque formation. Caries Research, 11, 243-61. 

It is superior to the zinc phosphate cement for bonding orthodontic bands to teeth (Clark, Phillips Norman, 1977). It has greater durability and there is less decalcification in adjacent tooth enamel. This latter beneficial effect must arise from the release of fluoride which is absorbed by the enamel, so protecting it in a clinical situation where caries-produdng debris and plaque accumulate. 

Controlled and sustained drug delivery has recently begun to make an impression in the area of treatment of dental diseases. Many researchers have demonstrated that controlled delivery of antimicrobial agents, such as chlorhexidine [128-130], ofloxacin [131-133], and metronidazole [134], can effectively treat and prevent periodontitis. The incidence of dental caries and formation of plaque can also be reduced by controlled delivery of fluoride [135,136]. Delivery systems used are film-forming solutions [129,130], polymeric inserts [132], implants, and patches. Since dental disease is usually chronic, sustained release of therapeutic agents in the oral cavity would obviously be desirable. 

Pathology. Tooth plaque produces acids during the fermentation of dietary carbohydrates, causing the underlying tooth mineral to solubilize (demineralization). Upon restoration of a neutral plaque pH, mineral can reprecipitate (remineralization). When this equilibrium is lost, net demineralization occurs, causing dental caries. 

Beighton D and Lynch E (1995) Comparison of selected microflora of plaque and underlying carious dentine associated with primary root caries lesions. Caries Res 29, 154-158. 

Schiipbach P, Osterwalder V and Guggenheim B (1995) Human root caries microbiota in plaque covering sound, carious and arrested root surfaces. Caries Res 29, 382-395. 

Peroxidases from saliva, crevicular fluid, bacteria, and fungi may contribute to this reaction in caries lesions. Although deeper layers of the carious microflora are assumed to be anaerobic, the oxygen required for the reaction may reach the deeper parts of the plaque via oxygen channels (Marquis, 1995). Lactobacilli, however, cause browning of dentin in the absence of tyrosinase (Dreizen et ah, 1957). 

Bacterial pigments. Some bacteria commonly found in caries lesions are known to produce pigments. For example, the black staining of plaque is related with Actinomyces (Slots, 1974), but its chemical nature remains unknown. Black pigmented Prevotella produces both iron sulphide and heme pigments (Shah et ah, 1979). In addition, Propionibacterium forms porphyrins (Lee et al., 1978). Bacterial iron-binding peptides, which can contribute to discoloration, increase in the saliva of subjects with a high caries frequency (Nordh, 1969). 

Aside from the Maillard reaction, other covalent modifications of amino acids and proteins are possible within the caries lesion, which merit future investigation. For example, certain oral microorganisms excrete y-glutamyl transferases. These enzymes catalyse the formation of cross-links between glutamic acid and lysine residues of proteins. In addition, N-acyl amino acids are present in plaque, which adsorb to mineral surfaces. 

The most important form of protection against caries involves avoiding sweet substances (foods containing saccharose, glucose, and fructose). Small children in particular should not have very sweet drinks freely available to them. Regular removal of plaque by cleaning the teeth and hardening of the dental enamel by fluoridization are also important. Fluoride has a protective effect because fluoroapatite (see A) is particularly resistant to acids. 

Although chlorhexidine affects virtually all bacteria, gram-positive bacteria are more susceptible than are gram-negative organisms. Furthermore, Streptococcus mutans and Antinomies viscosus seem to be particularly sensitive. S. mutans has been associated with the formation of carious lesions in fissures and on interproximal tooth surfaces and has been identified in large numbers in plaque and saliva samples of subjects with high caries activity. 

Mild tooth staining has been observed after use of stannous fluoride products. The ADA Council on Dental Therapeutics endorses fluorides for their caries-inhibiting effect but not for plaque inhibition. 

The presence of S. mutans and other cariogenic bacteria contributes towards the formation of a biofilm known as dental plaque, and their metabolism of fermentable carbohydrates in the diet leads to the formation of acids [12]. Dental caries has been described as a complex imbalance in physiologic equilibrium between tooth mineral and biofilm [13]. Biofilms imply the involvement of microbiological species [14], but the key concept included within this definition is that the bacteria involved are native to the body, not a group of specific invasive bacteria causing infection [14]. 

Exposure to fluoride, by whatever means, leads to moderately elevated levels of fluoride in the saliva and the plaque. This is sufficient to help caries prevention by inhibiting demineralisation and assisting remineralisation. These processes are discussed in detail in the following sections of this chapter. 

Remineralisation occurs when partly dissolved crystals are induced to grow by precipitation of the mineral-forming ions Ca + and POl". This is a natural process that occurs as a result of the concentration of these ions in saliva [23] and it serves to oppose the demineralising effects of caries. The processes involved are complex [24] and involve dynamic activity at the interface between the tooth, the saliva, the pellicle and the plaque. Fluoride plays a role in enhancing these processes, and though this is not the only contribution that fluoride makes to protect the tooth from caries, it is nonetheless an important one. 

O. Fejerskov, A.A. Scheie, F. Manti, The effect of sucrose on plaque pH in the primary and permanent dentition of caries-inactive and -active Kenyan children, J. Dent. Res. 71 (1992) 25-31. 

H.C. Margolis, J.H. Duchworth, E.C. Moreno, Composition of pooled resting plaque fluid from caries-free and caries susceptible individuals, J. Dent. Res. 67 (1988) 1468-1475. 

V. Baelum, O. Fejerskov, A. Kuseler, Approximal plaque pH follow/ing topical applications of standard buffers in vivo. Caries Res. 28 (1994) 116-122. 

Namba, T., M. Tsunezuka, D. M. R. B. Dissanayake, et al. Studies on dental caries prevention by traditional medicines (part VII) screening of ayurvedic medicines for anti-plaque action. Shoyakugaku Zasshi 1985 39(2) 146-153. 

Mouthwashes are aqueous concentrated solutions containing one or more active ingredients and excipients. They are used by swishing the liquid in the oral cavity. Approximately 15-30 ml. of mouthwash are used for single mouthful of rinse for about a minute. Mouthwashes can be used for therapeutic and cosmetic purpose. Therapeutic mouthwashes are used to reduce plaque, dental caries, gingivitis and stomatitis while cosmetic mouthwashes are used to reduce bad breath and it contains used antimicrobial and/or flavoring agent. Mouthwashes other than used for cosmetic purpose, should only be used under the direction of physician/dentist since it contains certain medicines. 

Ammonium ions—To reduce the incidence of dental caries, ammonium ions are applied locally in the oral cavity. Certain dentifrices which contain ammonia or ammonium compounds e.g. dibasic ammonium phosphate and urea carbamide which liberates ammonia in the mouth are used. They decrease the number of acid producing pathogen, decrease the acidity of the oral cavity and dissolve the dental plaques. 

Application of sialidase inhibitors for medical use is still in a premature state. It is imaginable that inhibitors would be useful drugs in infections, caused by micro-organisms, that lead to extensive production of sialidase, for example, in gas edema.371 In the oral cavity, plaque formation and dental caries may be influenced by desialylation of salivary glycoconjugates,399 and bacterial sialidases may play a role therein. This process may be retarded by secretion of the inhibitor Neu2en5Ac in saliva at concentrations which, in some cases, were found to be close to the K value for sialidases.34... 

Sucrose and Dental Caries The most prevalent infection in humans worldwide is dental caries, which stems from the colonization and destruction of tooth enamel by a variety of acidifying microorganisms. These organisms synthesize and live within a water-insoluble network of dextrans, called dental plaque, composed of (al 6)-linked polymers of glucose with many (a 1 >3) branch points. Polymerization of dextran requires dietary sucrose, and the reaction is catalyzed by a bacterial enzyme, dextran-sucrose glucosyltransferase. 

The cariogenicity of lactitol has also been investigated. Linko et al. (1980) reviewed early studies showing that lactitol was not readily fermented by Streptococcus mutans and other oral bacteria. In vivo studies, reviewed by van Velthuijsen (1979), were concerned with the reduction of pH in dental plaque after consumption of chocolates made with lactitol, there was evidence that lactitol did not increase the incidence of dental caries. 

Caries. Oral bacteria, in association with glycoproteins from saliva, form a sticky coating on the surface of the teeth known as plaque. When carbohydrates... 

Unlike erosion, caries damage is localised to areas where plaque most readily accumulates, i.e. between the teeth, at the gum margins and in fissures and irregularities on the tooth surfaces. 

The pathogenesis of dental caries may involve three distinct processes (1) adherence of the bacteria to the tooth, (2) formation of glycocalyx due to synthesis of a sticky glucan by the action of the bacterial enzyme glucosyl transferase on sucrose, and (3) accumulation of biobUm (plaque), within which there is continuing acid production by constituent bacteria (including streptococci and lactobacflli) able to metabolize carbohydrates at low pH values. This acid demineralizes an enamel. 

Complexes of Ca, CPP and phosphate have also been shown to reduce caries in a dose-dependent fashion, by increasing the level of calcium phosphate in the plaque, thus influencing the demineralization/remineraliza-tion process (Reynolds et al., 1995), and to significantly reduce the adherence of Streptococci to tooth enamel (Schuepbach et al., 1996). 

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