Plaque fluoride

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. 

Whitford GM, Wasdin JL, Schafer TE, Adair SM Plaque fluoride concentrations are dependent on plaque calcium concentrations. Caries Res 2002 36 256-265. 

Duckworth RM, Jones Y, Nicholson J, Jacobson APM, Chestnutt IG Studies on plaque fluoride after use of F-containing dentifrices. Adv Dent Res 1994 8 202-207. 

Opinion favours the steady flow of saliva as the main source of plaque fluoride, even though saliva contains only 0-01 to 0-02 ppm of fluoride or even less. Smaller amounts are believed to be derived from the intermittent exposure of the plaque to food and drink. Calculations show that the absolute amounts of fluoride in plaque are very small for example, the total amount present in 10 mg of plaque containing 20 ppm is equivalent to that present in only 10-20 ml of saliva or 0-2 ml of fluoridated water. 

Fluorides. Most woddwide reductions in dental decay can be ascribed to fluoride incorporation into drinking water, dentifrices, and mouth rinses. Numerous mechanisms have been described by which fluoride exerts a beneficial effect. Fluoride either reacts with tooth enamel to reduce its susceptibihty to dissolution in bacterial acids or interferes with the production of acid by bacterial within dental plaque. The multiple modes of action with fluoride may account for its remarkable effectiveness at concentrations far below those necessary with most therapeutic materials. Fluoride release from restorative dental materials foUow the same basic pattern. Fluoride is released in an initial short burst after placement of the material, and decreases rapidly to a low level of constant release. The constant low level release has been postulated to provide tooth protection by incorporation into tooth mineral. 

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. 

The addition of therapeutic or cosmetic agents to dentifrices has paralleled advances in knowledge about factors affecting the human dentition. Agents added to dentifrices can act directly on the host tooth stmcture or on specific oral accumulations, for example, the principal action of fluoride is on the tooth enamel. The primary action of an abrasive, however, is on an accumulated stained pellicle. Oral accumulations of interest to preventive dentistry are dental pellicles, dental plaque, dental calculus (tartar), microbial populations responsible for oral malodor, and oral debris (food residues, leukocytes, etc). Plaque is most important because of its potential to do harm. 

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. 

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. 

Nixon277 compared atomic absorption spectroscopy, flame photometry, mass spectroscopy, and neutron activation analysis as methods for the determination of some 21 trace elements (<100 ppm) in hard dental tissue and dental plaque silver, aluminum, arsenic, gold, barium, chromium, copper, fluoride, iron, lithium, manganese, molybdenum, nickel, lead, rubidium, antimony, selenium, tin, strontium, vanadium, and zinc. Brunelle 278) also described procedures for the determination of about 20 elements in soil using a combination of atomic absorption spectroscopy and neutron activation analysis. 

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. 

A few well-controlled clinical studies suggested a potential plaque-inhibiting effect for dentifrices containing staimous fluoride. However, these results were most likely due to the stannous ion rather than to fluoride the positive charge of the stannous ion may interfere with bacterial membrane function, bacterial adhesion, and glucose uptake, thereby inhibiting the formation of plaque. 

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. 

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. 

When fluoridated toothpastes are used, one of the effects is that fluoride levels increase, and such an effect is detectable after a single use [156]. This fluoride is taken up both by the dental plaque [157,158] and by the demineralised enamel [159] as a result of increases in fluoride levels in saliva between 100 and 1000 times the initial level. Although this initial elevation in concentration lasts for only 1-2 h [160], regular use of fluoridated toothpaste can raise the general level of fluoride in the saliva. This shift in baseline fluoride level can be maintained over considerable periods of time [157,158]. 

Mouthrinses containing fluoride consist of a concentrated solution that is prepared for use at daily or weekly intervals. As is the case for toothpastes, fluoride from mouthrinses is retained by the dental plaque and increases the concentration in saliva [172]. Mouthrinses have the advantage that their viscosity is low [173], which is aided by the use of ethanol as at least part of the carrier liquid. This enables mouthrinses to penetrate into interproximal regions, and hence carry the fluoride to parts of the tooth that are difficult to access by other means, for example, with toothpastes. 

D.T. Zero, R.F. Raubertas, J. Fu, A.M. Pedersen, A.L. Hayes, J.D.B. Featherstone, Fluoride concentrations in plaque, whole saliva, and ductal saliva after application of home-use topical fluorides, J. Dent. Res. 71 (1992) 1768-1775. 

The levels of fluoride in body fluids (plasma, saliva, urine) give some indication of recent fluoride intake. Fluoride ion does not produce any metabolites, and so is itself the measured indicator. This indicator, however, does not well reflect the fluoride body burden or the accumulation of fluoride in the body, because the relation between fluoride concentrations in bone and in extracellular fluids is incompletely defined. The concentration of fluoride in plasma, urine, saliva and dental plaque is dependent on the intake via water, diet, fluoride supplements and fluoride-containing dentifrices [92-97],... 

Stannous fluoride Fluoride Treat tooth decay, prevent tooth plaque and inflammation of gums Flo-Gel, Gel-Kam 0.4... 

In general, saliva (as well as plaque fluid) is supersaturated with respect to calcium-phosphate salts, and they prevent tendency to dissolve mineral crystals of teeth. Moreover, precipitation of calcium-phosphate salts that include hydroxyapatite may also occur (remineralization) in early lesions of tooth surfaces injured by acidic bacterial products (i.e., lactic acid). Salivary fluoride facilitates calcium-phosphate precipitation, and such crystals (i.e., fluorapatite) show lower acid solubility properties that lead to an increased caries preventive effect. The increase of pFI (i.e., buffer capacity and pH of saliva, as well as ureolysis in dental plaque) also facilitates crystal precipitation and remineralization (4, 13). 

Dental plaque also tends to concentrate fluoride. This could increase possible antienzymatic activity. Some caries protection from this may be expected. Additionally, studies have suggested that topical application of fluoride may also reduce smooth surface plaque, with a resulting beneficial effect on the periodontal tissues. 

Currently accepted dentifrices contain sodium mono-fluorophosphate, sodium fluoride, or, less frequently, stannous fluoride, all of which reduce caries by approximately 25% when used daily. In some clinical studies, stannous fluoride dentifrices stained teeth, particularly in pits and fissures. This stain is related to the tin in this compoimd, which adheres to plaque. The significance of this staining and its esthetic problems have resulted in a decreased usage in dentifrices. Stannous fluoride dentifrices are marketed in a plastic container because a reaction of stannous ions at an acid pH occurs when conventional soft metal tubes are used. 

Clinical data from several long-term studies in Europe have demonstrated the effectiveness of the use of a dentifrice containing organic amine fluorides. The amine fluorides also have strong plaque-reducing properties. However, although the amine fluorides may be more effective for caries reduction than other forms of fluoride, the FDA has not allowed these products to be extensively tested in this country. 

Fluorides are purported to have some antiplaque properties. The most widely used topical fluorides are stannous fluoride, acidulated phosphate fluoride, and sodium fluoride. Of the fluorides, short-term studies of stannous fluoride have been promising. However, long-term published studies showed lower plaque scores, but the differences were not significant. 

Stannous fluoride products are accepted by the ADA for their ability to deliver fluoride but have not been approved for their plaque-reducing properties. Examples of accepted products are Activux Basic Control, Gel-Kam, Gel-Tin, Perfect Choice, Pro-Dentx, Schein Home Care, and Super-Dent. 

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