The acidogenic potential of plaque from sound enamel, white spot lesions, and cavities in children.

An ion-sensitive field-effect transistor was used to monitor changes in pH following exposure of plaque samples to sucrose. A total of 9O plaque samples were removed from sound enamel, incipient white spot lesions, or cavities of 84 children and placed in a microholder. Sucrose(5% solution) was placed onto the plaque sample and the pH followed for 30 rain by inserting the microelectrode into the plaque. Plaque samples from the white spot lesions showed faster decreases in pH and significantly greater quantities of acid were produced in comparison to the control plaques. These results demonstrate that the plaque found over white spot lesions in children has greater acid-producing activity than plaque from nondisease-associated sites. Dental caries results from the production of acids from dietary fermentable carbohydrate by cariogenic plaque bacteria. Minah and Loesche (1977) demonstrated that plaque from carious tooth surfaces contained elevated levels of Streptococcus mutans and that the plaque fermented sucrose to acid more rapidly than plaque samples from control noncariogenic plaque. Duchin and van Houte (1978) analyzed for the presence of S. mutans and lactobacilli in plaque removed from incipient white spot lesions on buccal tooth surfaces and cavitated carious lesions on buccal and approximal tooth surfaces in children. The plaque from the carious sites frequently showed a 100-fold elevation in the presence of S. mutans compared to adjacent control sites. The purpose of the present study was to compare the acid-producing potential of plaque from sound enamel, white spot lesions, and cavitated caries in children. tal Hospital outpatient clinic. The patients ranged in age from 4 years, 4 months to 8 years, 7 months with a mean of 7 years, 1 month. Final diagnosis of sound enamel or white spot lesions without cavitation was made using a mirror and probe. White spot lesions were defined as slightly roughened, chalky areas not yet at the stage of clinically detectable cavitation (Duchin and van Houte 1978). Cavitated primary teeth had carious lesions not involving pulp. Plaque Sampling and Acid Production from Sucrose Plaque samples were removed from the buccal surface of maxillary permanent central incisors, lateral incisors or first molars and from the lingual tooth surface of mandibular first permanent molars. Also, plaque was obtained from the labial and buccal surfaces of primary maxillary anterior (from right canine to left canine) primary second molars, or the lingual surface of mandibular second primary molars. A total of 90 samples were obtained from the various sites (Table 1). In each procedure a small amount of plaque (2.0 mg wet weight) was obtained usinga sterile wooden stick and the plaque was transferred into a plastic tube" (inner diameter 1.0 mm; depth 1.0 mm) which had been sealed at the bottom with silicon rubber, b Approximately 5 ~tl of sterile sucrose (5% w/v in 10 mM phosphate buffer solution, pH 6.86 at 25° C) was added onto the plaque (Fig 1). A combination hydrogen-ion sensitive field-effect transistor electrode c was inserted slowly into the sucrose solution and then lowered into the plaque with the aid of a mechanical manipulator. ~ The pH responses were recorded continuously for 30 min at room temperature with a strip chart recorder" connected to a pH meter! Methods and Materials