Fluoride ions dentifrices

Fluorides ia small (1 ppm ia water, 0.1% ia dentifrices) quantities have been shown to provide dramatic reduction ia dental decay. Fluorides also show promise for bone treatment and ia pharmaceuticals (qv) (see also Chemotherapeutics, anticancer Steroids). However, larger quantities of fluorides can lead to dental fluorosis, bone fracture, and even death. The oral LD q for free fluoride ion ia rats appears to be 50 to 100 mg/kg body weight based on LD q values for several fluorides. 

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],... 

Sodium fluoride as an ingredient in dentifrices has been the subject of a number of clinical investigations. Recent studies of sodium fluoride dentifrices formulated to ensure ready availability of fluoride ions have shown anticaries benefits similar to those obtained in clinical caries trials with dentifrices containing stannous fluoride and sodium monofluorophosphate. 

B. Fluoride Appropriate concentrations of fluoride ion in drinking water (0.5-1 ppm) or as a dentifrice additive have a well-documented ability to reduce dental caries. Chronic exposure to the ion, especially in high concentrations, may increase new bone synthesis. It is not clear, however, whether this new bone is normal in strength. Clinical trials of fluoride in patients with osteoporosis have not demonstrated a reduction in fracmres. Acute toxicity of fluoride (usually caused by ingestion of rat poison) is manifested by gastrointestinal and neurologic symptoms. Chronic toxicity (fluorosis) includes ectopic bone formation and exostoses. 

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. 

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. 

Vogel GL, Zhang Z, Chow LC, Schumacher GE Changes in lactate and other ions in plaque and saliva after a fluoride rinse and subsequent sucrose administration. Caries Res 2002 36 44-52. Duckworth RM, Morgan SN Oral fluoride retention after use of fluoride dentifrices. Caries Res 1991 25 123-129. 

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