title: Intra- and inter-individual variation in salivary flow rate, buffer effect, lactobacilli, and mutans streptococci among 11- to 12-year-old schoolchildren.
abstract: Both intra- and inter-individual variation in salivary flow rate, buffer effect, and the levels of salivary mutans streptococci and lactobacilli were analyzed in 128 11-year-old children. The follow-up period was 9 months, with six saliva samplings done at regular intervals. Inter-individual variation was relatively large in paraffin-stimulated salivary flow rate: low (< 1.0 ml/min) and high (> or = 2.0 ml/min) flow rates were measured in 18% and 13% of the children, respectively. Intraindividual variation during the follow-up period was found in 63% of the boys and in 73% of the girls. The buffer effect stayed stable in all samplings in 59% of the boys and in 42% of the girls. Buffer effect was significantly (p < 0.001) lower in girls than in boys. Mutans streptococci were analyzed by a chair-side method (Strip mutans test) and by cultivation on mitis-salivarius-bacitracin (MSB) agar plates. The results of the two methods correlated highly significantly (r = 0.79, p < 0.001). With the Strip mutans test no variation in test scores occurred in 49% of all subjects in all six samplings, whereas the respective percentage for MSB scores was only 19%. No variation in salivary lactobacilli occurred in only 18% of the subjects, and in 13% the intraindividual variation was as high as > or = 3 logs. These results show that in young teenagers with a developing dentition, simultaneous changes in behavioral, hormonal, and dietary factors make single-point measurements of salivary factors too unreliable for caries-diagnostic or predictive purposes.
authors.affiliation: Public Health Care, Salo, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Tukia-Kulmala
authors.forename: J
authors.initials: J
authors.lastname: Tenovuo
mesh_terms: D000362:Agar; D002021:Buffers; D002648:Child; D015169:Colony Count, Microbial; D003470:Culture Media; D004245:DMF Index; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000302:isolation & purification*; D008297:Male; D011933:Reagent Kits, Diagnostic; D012463:Saliva / Q000378:metabolism / Q000382:microbiology* / Q000502:physiology*; D012636:Secretory Rate; D013295:Streptococcus mutans / Q000302:isolation & purification*
chemical_list: D002021:Buffers; D003470:Culture Media; D011933:Reagent Kits, Diagnostic; D000362:Agar