In vitro demineralization of enamel by F-sensitive and F-resistant mutans streptococci in the presence of 0, 0.05, or 0.5 mmol/L NaF.
Lactate production and accompanying enamel demineralization by fluoride-sensitive and fluoride-resistant mutans streptococci were studied in an in vitro demineralization model in the presence of 0, 0.05, or 0.5 mmol/L NaF. The fluoride-resistant strains were derived from laboratory strains or were recently isolated strains from xerostomic patients on high-dose fluoride therapy. The demineralization model was composed of a cell suspension in a glucose-agarose gel overlying a bovine enamel block. Lactate and calcium content of the agarose were determined after 22-hour incubations at 37 degrees C. Fluoride-resistant variants of Streptococcus sobrinus 6715-15 produced less lactate and caused less demineralization than did the parent strain even in the presence of fluoride. On the other hand, fluoride-resistant variants of Streptococcus mutans C180-2 and of S. mutans GS-5 produced more acid and caused greater demineralization than did their respective parent strains, both in the absence and presence of fluoride. Two recently isolated fluoride-resistant S. mutans strains produced more lactate and demineralized enamel more than did two recently isolated S. mutans strains from normal human subjects, both in the presence of 0 and 0.05 mmol/L NaF. It is concluded that adaptation to fluoride resistance does not invariably reduce the cariogenicity of mutans streptococci nor the effectiveness of fluoride in preventing demineralization.
Van Loveren
C
C
Department of Cariology and Endodontology, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands.
Spitz
L M
LM
Buijs
J F
JF
Ten Cate
J M
JM
Eisenberg
A D
AD
D000818:Animals; D002417:Cattle; D003743:Dental Enamel / Q000378:metabolism / Q000382:microbiology; D003773:Dental Plaque / Q000378:metabolism / Q000382:microbiology; D004352:Drug Resistance, Microbial; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000096:biosynthesis; D019344:Lactic Acid; D012969:Sodium Fluoride / Q000008:administration & dosage / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects* / Q000378:metabolism; D016986:Streptococcus sobrinus / Q000187:drug effects* / Q000378:metabolism; D017001:Tooth Demineralization / Q000209:etiology* / Q000378:metabolism / Q000382:microbiology / Q000503:physiopathology
D007773:Lactates; D019344:Lactic Acid; D012969:Sodium Fluoride; D005947:Glucose