[Evaluation of cariogenic potential of Streptococcus mutans isolated from caries-free and -active persons: adherence properties to saliva-coated hydroxyapatite].
OBJECTIVE
In this study, authors used saliva-coated hydroxyapatite to simulate tooth surface in oral cavity to evaluate adherence of different Streptococcus mutans isolated from caries-free and -active persons to saliva-coated hydroxyapatite.


METHODS
Streptococcus mutans isolated from people with different carious experiences were divided into two groups: the caried-free group (DMFS = 0) including 19 persons and the caries-active group (DMFS > or = 6) including 40 persons. Totally 105 genotype Streptococcus mutans strains were obtains, including 22 strains from the caries-free group, and 83 strains from the caries-active group. The adhering properties of Streptococcus mutans (serotype c) strains were investigated, and different adhering properties were compared between the caries-free group and the caries-active group in order to find the correlationship between carious experiences and adhering properties of Streptococcus mutans. Saliva-coated hydroxyapatite was used to simulated tooth surface in oral cavity. Streptococci mutans were cultured in TPY liquid medium containing 3H-TDR in the same radioactive concentration. After being cultured in an anaerobic incubator for 18 hours, Streptococci mutans were radiolabelled by 3H-TDR. Saliva-coated hydroxyapatite and bacterial liquid(BSA = 0.52) were mixed for 90 minutes. Samples were assayed by using liquid scintillation counter, and binding abilities of strains were evaluated by the count per minute(cpm).


RESULTS
Binding abilities of strains were significantly different in two groups, Caries-active people harbored more Streptococci mutans with high binding abilities(cpm > 2000) than caries-free people did(P < 0.05). The binding abilities to saliva-coated hydroxyapatite were different between strains of differing genotypes isolated from the same person. Each person always harbored one or two strains with high binding abilities(cpm > 2000) in the caries-active group.


CONCLUSIONS
1. Different genotypes have different adhering properties. 2. In caries-active group, different genotype strains have synergic effects, and adhesion of high binding ability strains cause caries susceptibility. 3. The differences in binding properties of isolates might relate to differences in carious experiences.
Huang
X
X
Department of Oral Medicine, College of Stomatology, West China University of Medical Sciences.
Liu
T
T
Chen
Z
Z
Zhan
L
L
Yang
J
J
D001422:Bacterial Adhesion; D003731:Dental Caries / Q000382:microbiology*; D003733:Dental Caries Susceptibility; D017886:Durapatite / Q000032:analysis*; D006801:Humans; D012463:Saliva / Q000737:chemistry*; D013295:Streptococcus mutans / Q000302:isolation & purification / Q000472:pathogenicity*
D017886:Durapatite