The prevalence and number of salivary lactobacilli was determined in all sc
hoolchildren starting the 7th grade (12-13 yr; n = 1,578) in comprehensive
school located in Kumla, Sweden between 1987 and 1998. Whole saliva samples
were collected and transferred to dip-slides (Dentocult-LB) and incubated
in room temperature for 7 d. Caries data were collected from the dental rec
ords and from bitewing radiographs. Both the number of lactobacilli and the
prevalence of manifest caries and restorations exhibited a decreasing tend
ency and were significantly lower in 1998 than in 1987. The mean caries pre
valence (DFS) declined from 5.2 to 1.8. In 1987, 45% of the children harbou
red high or very high lactobacilli counts (greater than or equal to 10(5) C
FU/ml) in their saliva compared to approximately 10-15% at the later examin
ations. The proportion of children with no detectable counts varied between
4-29% during the study period, while children with low counts (10(3)-10(4)
CFU/ml saliva) constituted a clear majority at the recent samplings, With
such low levels in the population, the use of lactobacilli counts as a dida
ctic tool in dietary counselling must be called into question.