Finn Brudevold: discovery of acidulated phosphate fluoride in caries prevention.

Finn Brudevold was a distinguished leader in dental research, recipient of many honors, and a Past President of IADR. This article traces his scientific career and focuses on his discovery and development of acidulated phosphate fluoride (APF) for practical use in caries prevention. Brudevold noticed that the low pH of stannous fluoride was very effective in getting fluoride into enamel in vitro. He hypothesized that an acidulated preparation that included phosphate to minimize enamel dissolution by a common ion effect would permit faster exchange of hydroxyls with fluoride. The clinical efficacy of APF is compared with other methods of professionally applied topical fluoride agents.

Topical fluorides in caries prevention and management: a North American perspective.

A review of evidence-based literature indicates incomplete evidence for the efficacy of most measures currently used for caries prevention, with the exception of fluoride varnishes and the use of fluoride-based interventions for patients with hyposalivation. Not all fluoride agents and treatments are equal. Different fluoride compounds, different vehicles, and vastly different concentrations have been used with different frequencies and durations of application. These variables can influence the clinical outcome with respect to caries prevention and management. The efficacy of topical fluoride in caries prevention depends on a) the concentration of fluoride used, b) the frequency and duration of application, and to a certain extent, c) the specific fluoride compound used. The more concentrated the fluoride and the greater the frequency of application, the greater the caries reduction. Factors besides efficacy, such as practicality, cost, and compliance, influence the clinician's choice of preventive therapy. For noncavitated smooth surface carious lesions in a moderate caries-risk patient, the appropriate fluoride regimen would be semiannual professional topical application of a fluoride varnish containing 5 percent NaF (22,600 ppm of fluoride). In addition, the patient should use twice or thrice daily for at least one minute a fluoridated dentifrice containing NaF, MFP, or SnF2 (1,000-1,500 ppm of fluoride), and once daily for one minute a fluoride mouthrinse containing .05 percent NaF (230 ppm of fluoride). If the noncavitated carious lesion involves a pit or fissure, the application of an occlusal sealant would be the most appropriate preventive therapy. The management of the high caries-risk patient requires the use of several preventive interventions and behavioral modification, besides the use of topical fluorides. For children over six years of age and adults, both office and self-applied topical fluoride treatments are recommended. For office fluoride therapy at the initial visit, a high-concentration agent, either a 1.23 percent F APF gel (12,300 ppm of fluoride) for four minutes in a tray or a 5 percent NaF varnish (22,600 ppm of fluoride), should be applied directly to the teeth four times per year. Self-applied fluoride therapy should consist of the daily five-minute application of 1.1 percent NaF or APF gel (5,000 ppm of fluoride) in a custom-fitted tray. For those who cannot tolerate a tray delivery owing to gagging or nausea, a daily 0.05 percent NaF rinse (230 ppm of fluoride) for 1 minute is a less effective alternative. In addition, the patient should use twice or thrice daily for at least 1 minute a fluoridated dentifrice as described above for treatment of noncavitated carious lesions. In order to avoid unintentional ingestion and the risk of fluorosis in children under six years of age, fluoride rinses and gels should not be used at home. Furthermore, when using a fluoride dentifrice, such children should apply only a pea-size portion on the brush, should be instructed not to eat or swallow the paste, and should expectorate thoroughly after brushing. Toothbrushing should be done under parental supervision. To avoid etching of porcelain crowns and facings, neutral NaF is indicated in preference to APF gels for those patients who have such restorations and are applying the gel daily. The rationale for these recommendations is discussed. Important deficiencies in our knowledge that require further research on topical fluoride therapy in populations with specific needs are identified.

The case for reducing the current Council on Dental Therapeutics fluoride supplementation schedule.

The milder forms of dental fluorosis have increased in prevalence since the original epidemiologic surveys of the 1930s. Most studies of fluorosis have identified the use of supplements as a major risk factor. Fluorosis could be prevented, in part, by stopping the improper prescription of fluoride supplements in optimally fluoridated areas and by lowering the dosage currently recommended by the Council on Dental Therapeutics supplemental fluoride schedule. At a 1991 workshop at the University of North Carolina, five alternatives to the present ADA Council on Dental Therapeutics schedule were suggested; however, no consensus on dosage was reached. Recently, the Fédération Dentaire International adopted a dosage schedule of 0.25 mg F from birth to 3 years of age, 0.5 mg F from 3 to 5 years, and 1 mg F thereafter. At a 1992 Canadian workshop it was proposed that supplements should not be started until age 3, should be given only to those "at high risk" of caries, and only 0.25 mg F should be prescribed from 3 to 5 years of age. Similarly, in some European countries supplements are not recommended until 3 years, at which time 0.5 mg F is prescribed, but only "for children at risk." Australia is considering a dosage schedule starting with 0.25 mg F at 6 months, again only for those "particularly at risk of caries." Serious problems exist in limiting fluoride supplementation only to high-caries-risk children because they are not easily identifiable at a young age. Ideally, a dosage schedule should be based on body surface area or weight rather than simply age, and supplements should be in the form of lozenges for children over 2 years of age. A reduced fluoride supplement dosage schedule is proposed.

Caries-risk assessment.

Dental caries has a multifactorial aetiology in which there is an interplay of three principal factors: the host (saliva and teeth), the microflora (plaque), and the substrate (diet), and a fourth factor: time. There is no single test that takes into consideration all these factors and can accurately predict an individual's susceptibility to caries. The risk of dental caries can be evaluated by analysing and integrating several causative factors. These include caries experience (initial caries lesions and established caries defects, secondary caries and present caries activity), fluoride use, extent of plaque present, diet, bacterial and salivary activity and social and behavioural factors.

Evolution of professionally applied topical fluoride therapies.

Ever since researchers first realized the benefits of fluoride as an anticaries agent, they began investigating the effect of concentrated topical fluoride applications in reducing caries. Many forms of fluoride were studied, including solutions, gels or foams of sodium fluoride, stannous fluoride, organic amine fluoride, acidulated phosphate fluoride, and nonaqueous fluoride varnishes in an alcoholic solution of natural resins and difluorosilane agents covered by a polyurethane coating. All of these professionally applied topical agents have anticaries benefits, although these benefits and the ease of application vary. One trend that stands out in the evolution of professionally applied fluoride agents is the development of increasingly more user-friendly products.

The use of sodium bicarbonate in oral hygiene products and practice.

Early dentifrices contained natural ingredients, mostly in coarse particle form, and were quite abrasive. Salts, either sodium chloride, sodium bicarbonate, or a mixture of both, have also been used for tooth cleaning because of their ready availability and low cost. Because of both their relatively low intrinsic hardness and their high solubility, another advantage is low abrasivity. Their biggest disadvantage is a salty, unpalatable taste. Many modern dentifrices that contain sodium bicarbonate, either as the sole abrasive or one of several, disguise the saltiness with flavoring and sweetening agents. An almost inverse relationship exists between the percentage of baking soda in a dentifrice and its abrasivity. Sodium bicarbonate has no anticaries activity per se but is compatible with fluoride. In high concentrations, sodium bicarbonate is bactericidal against most periodontal pathogens. Most clinical studies have not found significant differences in periodontal response to baking soda as compared with other commercial dentifrices, probably because of its rapid clearance from the gingival sulcus. Sodium bicarbonate may not be the "magic bullet" for curing dental diseases, but its safety (if ingested), low abrasivity, low cost, and compatibility with fluoride make it a consummate dentifrice ingredient.

Indices to measure gingival bleeding.

Gingival bleeding is an objective, easily assessed sign of inflammation that is associated with several periodontal diseases. Many bleeding indices have been devised; some assess bleeding as simply present or absent, whereas others use grading in an attempt to assess severity of bleeding. The choice of which index to use depends on whether the purpose is an epidemiological survey, a clinical study, diagnosis and treatment, or patient motivation. Bleeding may be elicited manually with toothpicks, dental floss or a periodontal probe, but a controlled-force probe, although more expensive, causes less trauma and less false-positive bleeding from healthy tissues. As a predictor of periodontal disease progression, bleeding on probing has low sensitivity owing to a high frequency of false-positive responses, but has high specificity in that failure to bleed indicates health. There is evidence that smokers have less, or delayed, gingival bleeding when compared with non-smokers; therefore smoking needs to be controlled for in studies of gingival bleeding. Measurement of gingival bleeding tendency should be an integral part of a comprehensive oral examination. In clinical practice, the use of a graded bleeding index is more likely to identify sites that are at risk of further destructive activity. For monitoring individual patients, both for response to initial therapy and during maintenance, a modified Sulcus Bleeding Index (mSBI) with three bleeding scores is recommended in preference to dichotomous scoring of bleeding.

Current treatment modalities of oral problems of patients with Sjögren's syndrome: caries prevention.

Prevention of dental caries in patients with hyposalivation due to Sjögren's syndrome requires increasing host resistance and decreasing cariogenic organisms and their substrate. Although plaque control by scrupulous oral hygiene is important, particularly from a periodontal perspective, and restriction of dietary sucrose intake can limit caries, the most successful therapeutic and preventive measure has been the topical application of fluoride to the tooth surface, by the dentist, dental hygienist, dental auxiliary, and the patient. Studies on schoolchildren with normal salivary function who used fluoride dentifrices have shown that efficacy in caries prevention depends on (1) the concentration of fluoride used, (2) the frequency with which it is applied, and, to a certain extent, (3) the specific fluoride compound used. Controlled clinical studies are lacking, however, on patients with hyposalivation due to Sjögren's syndrome, and only limited data are available from patients with radiation-induced hyposalivation. Obviously it is not possible to run placebo control groups; nevertheless, there have been no head-to-head comparisons of fluoride rinses, or of stannous fluoride, acidulated phosphate fluoride, or sodium fluoride gels, and thus no single protocol can be recommended. Accordingly, different centers have used these products interchangeably--for example, selecting a rinse regimen if patients complain of gagging when using a gel applied in a tray, or if the cost of the tray is prohibitive. Recent innovations that show promise for treatment of high-caries-risk patients with hyposalivation are the use of fluoride rinses in combination with chlorhexidine rinses or gels and the professional application of high-concentration chlorhexidine varnishes to the teeth.

The use of sodium bicarbonate in oral hygiene products and practice.

Early dentifrices contained natural ingredients, mostly in coarse particle form, and were quite abrasive. Salts, either sodium chloride, sodium bicarbonate, or a mixture of both, have also been used for tooth cleaning because of their ready availability and low cost. Because of both their relatively low intrinsic hardness and their high solubility, another advantage is low abrasivity. Their biggest disadvantage is a salty, unpalatable taste. Many modern dentifrices that contain sodium bicarbonate, either as the sole abrasive or one of several, disguise the saltiness with flavoring and sweetening agents. An almost inverse relationship exists between the percentage of baking soda in a dentifrice and its abrasivity. Sodium bicarbonate has no anticaries activity per se but is compatible with fluoride. In high concentrations, sodium bicarbonate is bactericidal against most periodontal pathogens. Most clinical studies have not found significant differences in periodontal response to baking soda as compared with other commercial dentifrices, probably because of its rapid clearance from the gingival sulcus. Sodium bicarbonate may not be the "magic bullet" for curing dental diseases, but its safety (if ingested), low abrasivity, low cost, and compatibility with fluoride make it a consummate dentifrice ingredient.

The fluoridation war: a scientific dispute or a religious argument?

Communal water fluoridation is not considered controversial by the vast majority of the scientific community; however, politically it has persisted as an issue that many legislators and community leaders have avoided because of an aura of dispute, it has been a battleground for vigorous opposition by a very small but outspoken minority who have fought it with the dedication of religious zealots. This paper reviews the nature of the opposition, who they are, the broad thrust of their arguments, some of the specific issues they have raised, and their techniques.

Problems in caries diagnosis.

This paper reviews some of the problems in the diagnosis of primary and secondary caries, particularly with respect to the questionable lesion that has neither penetrated to dentine nor cavitated. Because tactile diagnosis of caries with sharp probes can be unreliable as well as damaging, diagnosis should include careful visual inspection (preferably with magnification), radiographic examination, fibre optic transillumination (FOTI), and/or measurement of electrical resistance depending on the anatomical location. Probably the most important and difficult diagnostic decision for the clinician is whether the patient is at high, moderate or low risk of caries. Consideration of various factors in the patient's history, and clinical and laboratory examinations will assist in this classification of risk.

Preventing dental caries: breaking the chain of transmission.

Besides using all possible techniques to increase host resistance (fluoride, sealants) and decrease exposure to fermentable carbohydrates (for example, use of sugar substitutes), dentists must treat caries as infectious and transmissible. Antimicrobial agents are recommended.

Preventing dental caries: current and prospective strategies.

Strategies of caries prevention can be directed at the resistance of the host/teeth, at the diet, at the microflora or all three. The appropriate preventive interventions depend on the level of caries risk.

Current regulations and recommendations concerning water fluoridation, fluoride supplements, and topical fluoride agents.

In recent years, an increase in the prevalence of dental fluorosis, mostly of the very mild to mild category, has been seen in the United States. This paper therefore discusses the safety of dental fluoride products, primarily with respect to the risk of dental fluorosis due to chronic ingestion of these products by pre-school children. No change is indicated in the optimal fluoride level (0.7 to 1.2 ppm) for water fluoridation. A reduction in the dosage of fluoride supplements is recommended for children aged from three to six years (14.5 to 22 kg body weight) residing in communities with less than 0.7 ppm F. Physicians, pharmacists, and dentists need to be better educated in correctly prescribing fluoride supplements; such prescriptions should be based on the fluoride concentration of the domestic water supply and the child's weight/height/age. No change is recommended in the concentration of fluoride used in dentifrices and mouthrinses. The US Food and Drug Administration should require more explicit labeling of fluoride products with regard to avoidance of ingestion, use of small amounts, and need for supervised use by pre-school children. The efficacy of water fluoridation, fluoride supplements, and topical fluoride agents has been amply documented elsewhere.

Dental caries in the future: a global view.

Although the prevalence of caries has decreased markedly in children, adolescents, and young adults in most industrialized countries, caries continues to be the main reason for tooth loss, particularly among the high risk segment of the population. In many developing countries, where traditional dietary patterns have changed to include sugar-containing foods and beverages, caries prevalence has increased and will continue to do so in the immediate future. Accordingly, it would be a serious mistake to be complacent about caries prevention. In future industrialized countries will see computers playing a significant role in cariology, finding applications not only in research and practice administration but directly in clinical practice as well. They will be used in every operatory in the assessment of caries risk, the recording of caries prevalence, the direct storing of radiographic information, and the restoration of carious teeth, assisted by computer-aided design and computer-aided manufacture (CAD/CAM) technology. Fluoride therapy, both systemic and topical, will continue to be the basis of caries prevention. Dental sealants, which are highly effective in protecting pits and fissures when applied soon after the teeth erupt, will be more widely used in the future when insurance plans will pay for prevention. Substitution of sucrose and syrups by non-fermentable sweetening agents can also reduce caries increments, but most agents are more expensive than sucrose and require consumer education to pay for the additional cost. Caries, as an infectious and transmissible disease, is amenable to prevention by interfering with the chain of transmission or by suppressing the putative pathogens, the mutans streptococci, in infected patients.(ABSTRACT TRUNCATED AT 250 WORDS)