Caries relationship

Table 3b also highlights the fact that the inverse calculus-caries relationship is largely independent of fluoride experience. Four fluoride concentrations were tested over the 6 trials 0,1000,1500 and 2500 ppm F as sodium monoflu-orophosphate (SMFP or Na2FP03) in alumina- or insoluble sodium metaphos-phate-based dentifrices. Average differences in caries increments between calculus-prone and calculus-free subjects for each fluoride level were all in the range 20-27%. 

An inverse relationship would mean that the absence of calculus could be a useful predictor of caries. Historically, however, any calculus-caries relationship has often been obscured by other factors. Firstly, the prevalence of both calculus and caries increases with increasing age [1,2] and, second, both conditions are expected to correlate positively with poor oral hygiene [3-5]. These trends could be the reason why Schroeder [1] found no consistent relationship between clinical observations of calculus and caries experience in the first major review of the topic. 

The evidence concerning a relation of heredity to dental caries susceptibility in human beings is confused by the overlapping factors associated with the family unit and the locality in which it resides. In experimental animals, definite relationships between heredity and caries incidence have been demonstrated.25... 

It is tempting to speculate on the nature of the pigment formed in the caries process and on its relationship with caries arrestment. Knowledge of the cause of caries arrestment may help provide ways to stop caries in a preliminary phase. However, many causes could account for the discoloration in caries, often explaining the different opinions dentists have on this matter. Therefore, a review of the chemical backgrounds of the color changes was felt necessary. 

Fluoride supplements are recommended by medical societies in some countries for caries prevention, especially if the concentration of fluoride in drinking water is low. It is likely that past use of dietary fluoride supplements has been a prime factor in the increased prevalence of dental fluorosis, a relationship which may stem from the days when fluoride supplement schedules were higher than they are today [11]. Table 7 shows a fluoride supplement dosage schedule that was approved for U.S. and Canadian children by the American Dental Association and Canadian Paediatric Society [8] and a fluoride supplement dosage schedule approved by German Nutrition Society, Austrian Nutrition Society, Swiss Society for Nutrition Research and Swiss Nutrition Association [165]. 

The Standing Committee on the Scientific Evaluation of Dietary Reference Intakes [8] in 1997 defined the Al for fluoride, stating Based on the extensively documented relationship between caries experience and both concentration of fluoride in water and fluoride intake, the Al for fluoride from all sources is set at 0.05 mg/day/kg body weight. This intake range is recommended for ages above 6 months because it confers a high level of protection against dental caries and is associated with no known unwanted health effects . 

The relationship between fluoride and dental caries was first noted in the early part of the 20th century when it was observed that residents of certain areas of USA developed brown stains on their teeth. In the 1930s, it was observed that the prevalence and severity of this type of mottled enamel was directly related to high amounts of ingested fluoride [34],... 

The basic amino acids of serum proteins. III. A chemical relationship between serum proteins of various origins. Ibid., 104, 347 (1934). With D. C. Darrow and M. K. Cary. 

Many excipients used by the pharmaceutical industry in the last 15 years in sugar-free medical preparations probably come under the category of essentially new excipients. Pressure for their introduction has been encouraged by the definite relationship between the dietary consumption of sucrose and the incidence of dental caries. " "" These materials include intense sweeteners such as saccharin and cyclamate plus bulk sweeteners such as the polyols sorbitol, xylitol, and lactitol. These materials are all either approved for food use or have pharmacopoeia monographs in existence or in draft. Fiterature reviews show number of... 

The dental examination of thousands of children and adults and the analysis of hundreds of water supply sources for fluoride have shown a remarkable relationship between the concentration of waterborne fluoride and the incidence of dental caries. As a result, the following general relationships between fluoride level and dental caries can be stated (1,5,9,12) ... 

Of those studies in which both conditions have been monitored, it will become clear below that the anticipated inverse relationship between calculus and caries is much more evident in the currently analysed, Unilever-sponsored, clinical trials than in many others. A major reason for this is that the former studies were mostly restricted to a narrow age range of subjects. 

Table 2. Relationship between caries and calculus prevalence at baseline [subjects in all studies aged 11-13 years at baseline]... 

The baseline data of table 2 show that caries prevalence is significantly lower in calculus-prone subjects than in calculus-free subjects in 5 of the 6 studies (average difference = 16%). The caries difference varies from one study to another, possibly because of differences in the clinicians interpretation of the scoring system, but overall the inverse relationship between calculus and caries is clear. 

The inverse relationship is again manifested in the increment data of table 3a. Children classified as calculus-formers at the start of a trial produced over 20% fewer caries lesions on average during the 3 years than their initially calculus-free counterparts. The baseline classification for calculus proneness also proved to be a good predictor of calculus status at the end of a trial. 

It is perhaps not surprising that a similar relationship exists between baseline calculus status and both mean baseline caries prevalence and corresponding mean 3-year caries increment. This is because a direct relationship between baseline caries prevalence and subsequent caries incidence has long been established. For example, we demonstrate elsewhere [17] that such a relationship exists for the Lanarkshire clinical trial data. Moreover, when the same data are separated into baseline calculus-prone and calculus-free groups, the former group has a consistently lower caries increment over the entire range of baseline caries prevalence. 

Table 3 a Relationship between calculus prevalence and caries incidence at trial end... 

Table 4. Relationship between caries incidence and calculus prevalence at the end of the Isle of Lewis study... 

We conclude that the above Unilever-sponsored studies demonstrate unequivocally an inverse relationship between calculus and caries for subjects of similar age. Furthermore, the magnitude of the difference in caries experience between calculus-formers and calculus-free schoolchildren is clinically significant. Baseline calculus status would therefore appear to be a useful stratifying factor during subject selection for caries clinical trials. 

Recent calculus reviews [16, 30, 31] have not mentioned the possible relationship between caries and calculus. White [31] noted correlations between supra-gingival calculus and factors such as plaque and oral hygiene but not caries, though his review is focussed more on potential links to gingivitis. However, two papers in this time period do discuss the relationship. 

Pattanapom and Navia [32] reported a study of calculus, caries and gingivitis in a young Thai population with high calculus prevalence. They found no relationship between calculus and caries, which may have been because their no calculus group was not actually calculus-free and/or because caries prevalence was low, 42% of subjects being caries-free. 

Ashley and Wilson [82] reported inverse relationships between 3-year caries increments and levels of calcium and inorganic phosphorus in the plaque. Of importance, these authors were able to show that the time relationship between caries diagnosis and plaque sampling appeared to be crucial. They had taken both caries and plaque measurements yearly during a 3-year clinical trial. Plaque calcium and phosphorus data correlated significantly with the 1-year DFS increments obtained one year later, but did not correlate with the corresponding 1-year DFS increments obtained one year earlier. 

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