Testing Caries Activity By Acid Production in Saliva

Abstract

A quick, simple, accurate method of evaluating dental caries activity of individuals, before the actual dissolution of enamel begins, would be a valuable aid in studies and treatments of dental caries because knowledge of caries activity would permit the dentist to plan his dental treatment program more intelligently and investigators could study methods of controlling dental caries more efficiently. Several methods of testing for dental caries activity have been reported, most of them based upon interpretations of studies of the oral flora, or upon the action of oral bacteria on carbohydrates. A brief outline of the better known tests follows:(1) Lactobacillus acidophilus colony counts [Hadley, Bunting and Delves (1)1. Studies are made of the number and types of colonies of Lactobacillus acidophilus which will grow in 48 hours on tomato agar (pH 5.0) plates after inoculation with 0.1 c.c. of a 1 in 5 dilution of saliva collected while the patient is chewing paraffin. High colony counts indicate caries activity while counts 0-100 indicate caries inactivity.(2) Direct microscopic study of plaque material [Blayney (2) 1. Plaques carefully removed from tooth surfaces under observation are stained and studied. Results indicate that caries active areas show plaques containing innumerable cocco-bacilli, while caries immune areas show a mixed flora of a different nature.(3) Enamel decalcification test [Fosdick, Hansen and Epple (3)1. Powdered enamel is suspended in a mixture of 6 c.c. of stimulated saliva and 0.2 gm. of glucose and agitated in a 3700 water bath for 4 hours. The amount of enamel which is dissolved is calculated by titration with N/100 KMmOj. As enamel dissolution increases above 9-10 mg. increase in caries activity is reported.(4) Study of pH of plaques on tooth surfaces [Stephan (4) ]. Using an antimony electrode, Stephan demonstrated that dental plaques varied in their pH, and those of low pH were apparently in caries active areas.(5) Fermentation Test [Snyder (5) ]. A 0.2 cc sample of stimulated saliva is incubated in 5 to 7 cc. of culture media containing Brom-cresol-green indicator. Formation of acid is shown by color change of indicator in 48 hours; saliva samples from caries active patients produce more acid than salivary samples from caries inactive patients.The present report concerns another method. of testing for dental caries activity. Our test is based upon the premise that acidogenic organisms are more nuimerous and more active in saliva from caries active patients, so that when a freely fermentable carbohydrate is added, acid production quickly follows.

Microbiological Predictors of Caries Risk

“…These include, for example: Wach's test, the determination of pH and titratable acidity in a saliva-glucose mixture (Wach et al, 1943); Rickles' test, involving the evaluation of acid production in a salivasucrose mixture with indicators (Rickles, 1953); a test involving the application of an indicator to the teeth to demonstrate acid production to "dangerous levels" (Hardwick, 1960); the Treatex test, involving the evaluation of reduction activity of salivary bacteria (Rapp, 1962); and a test involving amylase activity in saliva (Florestano et al, 1941). At present, the bestknown test is still the Snyder test, which is a colorimetric test for the indirect determination of the counts of L in saliva.…”

Laboratory Investigations on the Relation of Fluorine to Dental Caries on Tyneside and District

“…If the solubility of teeth is related to caries at all, the finding that the solubilities of adult teeth from high and low fluorine towns appear not to differ raises the interesting possibility that the reduction in the anti-caries effect of fluorine with advancing age (Weaver, 1944b;Forrest et al, 1951) may be related to the loss of this difference in solubility. The smallness of the difference in caries among adults of high and low fluorine areas has previously been interpreted as a gradual reaching, by middle life, of the maximum possible number of cavities-a state of affairs occurring at a younger age in a low fluorine area.…”

“…The acid production of the saliva was then measured by a modification of the test of Wach et al (1943).…”

“…When the present work was begun in 1948 it was based on the figures of Weaver's 1943 survey showing that both 5-year-old and 12-year-old children in S. Shields had a DMF1 figure about 40% less than had N. Shields' children (Weaver, 1944a). The survey of 1949 showed that the "wartime diet" had altered the picture; among the 5-year-old children the DMF figure had fallen by 33 % in N. Shields but only by 10% in S. Shields and the DMF figures for this age-group were no longer strikingly different (Weaver, 1950 Parfitt and Bransby (1951) reported a lower figure, viz. 0-82.…”

Caries‐susceptibility Tests

“…The Wach test (Wach, 1943) determined pH and the change in titratable acidity after a four-hour incubation with glucose. The Rickles test (Rickles, 1953) is a colorimetric test involving a four-hour incubation of saliva in a Group correlation but unsatisfactory on an individual basis sucrose solution containing bromcresol green and bromcresol purple.…”