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Five Streptococcus mutans pairs (serotype c S. mutans 10449 and four clinical isolates of S. mutans: 123.1, LG1, OMFA, T10B) were used to find out if the xylitol-resistant (XR) natural mutants of the corresponding xylitol-sensitive (XS) S. mutans parental strains differ in their growth patterns in saliva. The isogenic X natural mutants of the parental S. mutans strains were selected after sequential cultivations in the presence of xylitol and glucose. The XR/XS strains pairs were grown in individual and pooled glucose-supplemented filter-sterilized salivas (one to five sequential cultivations). The two salivas used represented subjects with good or poor support of the growth of S. mutans in vivo. Protease and peptidase activities were determined from the saliva growth media and cell suspensions. Salivary protein profiles were analyzed using SDS-PAGE and native IEF before and after the cultivations. The growth properties of the XR/XS S. mutans pairs were similar in both individual and pooled salivas. Sequential cultivation of all strains did not show any differences in growth patterns. XS strains were inhibited by the presence of xylitol (2% w/v) in pooled saliva, as shown for other glucose-supplemented media. Protease and peptidase activities of the XR/XS S. mutans pairs were low and of similar magnitude. Also, the general hydrolytic properties of most XR/XS S. mutans pairs appeared similar as judged by the small growth-induced changes in salivary protein profiles. In conclusion, saliva, the source of nutrients for salivary microorganisms in vivo, favored neither the XR nor the XS strains of S. mutans.

Bioactive glasses contain oxides of calcium, sodium, phosphorus, and silicon in a proportion that provides the material with surface activity and concomitantly with the property of forming a strong bond with bone. Bioactive glasses have been tested as bone substitutes in different clinical situations. In an aqueous environment, Ca2+, Na+, PO4(3-) , and Si4+ are released from the glass, resulting in a rise in pH and in osmotic pressure in its vicinity. Since these are factors that potentially influence the viability of oral microorganisms at the dentogingival margin, we studied the effects of bioactive glass S53P4 on the oral microorganisms Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Actinomyces naeslundii, Streptococcus mutans, and Streptococcus sanguis. This was done by incubating each microbe in a suspension, in the presence of bioactive glass S53P4 in powder form. A. naeslundii was found to lose its viability within 10 min under the experimental conditions. A. actinomycetemcomitans, P. gingivalis, and S. mutans lost their viability within 60 min. Also for S. sanguis a significant loss of viability was seen within 60 min, but it was the only microbe that had any viable cells left after 60 min. Thus, in aqueous solutions the powdered bioactive glass S53P4 appears to have a broad antimicrobial effect on microorganisms of both supra- and subgingival plaque. Consequently, it could be useful as an ingredient in tooth-care products that may have beneficial effects on oral health both from a cariologic and a periodontal point of view.

In clinical studies, the beneficial effects of xylitol have been demonstrated in association with its daily, habitual use [1]. Furthermore, regular maternal xylitol consumption has been shown to de...

The fall in plaque pH after sucrose rinsing was monitored once a week for 9 (8) weeks in succession, to measure the weekly variation in the magnitude of pH drop in the same subject. The plaque pH was measured with a touch electrode placed interdentally between the first and second premolar. The subject rinsed his mouth with 10% (w/v) sucrose solution, and the plaque pH was thereafter monitored for 40 min. The minimum plaque pH (pHmin), the change between starting and minimum pH (delta pH), and the resting pH value were determined. The pH values of the maxilla and mandible differed. No difference was seen between the right and left sides. As a rule, intraindividual variation was lower in terms of pHmin values than in terms of delta pH values. It was concluded that pH assessment with the touch electrode appeared to show a small weekly variation intraindividually and to be sensitive enough to test the acidogenic potential of foods, but only in the maxilla.