Is a bacterial factor crucial in caries development of the youngest children?

Patrycja Proc, Renata Filipińska-Skąpska, Magdalena Wochna-Sobańska

The degree of risk of caries developing in children can be assessed by the count of salivary mutans streptococci (MS) and lactobacilli (LB). The sensitivity of these and of other predictive tests has been reasonably high in people with a high disease prevalence found in Poland. Mutans streptococci are the principal micro-organisms associated with the development of caries. Colonisation by mutans streptococci at an early age has been correlated with higher caries activity during childhood. In caries lesions both mutans streptococci (MS) and lactobacilli (LB) are often found. MS play an important role in both initation and progression of caries lesions, LB only in progressing cavitation. On the other hand the high levels of MS observed in some caries-free children indicated that simple presence of this bacteria is not sufficient for the development of caries (1, 2, 3).

The aim of the study is to determine the prevalence of mutans streptococci and lactobacilli in the population of Polish toddlers and its relationship with caries incidence.

MATERIALS AND METHODS

The dental investigation embraced 927 children between the ages of eight and sixty two months. 75 children, 38 girls and 37 boys, were randomly selected from the whole group. The structure of population is presented in Tab. 1. Mean age of selected group was 33,8 months. The investigation took place in four kindergartens choosen from the total number of 31 such institutions in Lodz.

Table 1. Structure of the population and mean dmft in each group of age. ± standard devation.

Age (in years)	Girls	Boys	Both		Mean dmft
Age (in years)	n	n	n	%	Mean dmft
2	7	8	15	19.9%	0.33?0.72
3	16	14	30	39.9%	2.75?3.41
4	9	11	20	26.7%	4.46?5.04
5	6	4	10	13.4%	4.68?4.88
Total:	38	37	75	100%	3.12?3.36

A sample of non-stimulated saliva (about 2 ml) was taken from each child using the disposable syringe, and a CRT bacteria(r) test (Vivadent) was performed. The samples were transported to Dental School. The preparation of sampling and incubation were carried out according to the step-by-step procedure described in the instruction:

1. collection of saliva in a suitable container;

2. removing the agar carrier from the test vial;

3. placing a NaHCO3- tablet at the bottom of the vial;

4. wetting both agar surface with saliva, using a pipette;

5. placing the test vial in the incubator, and incubate at 37 grad C for 48 hours;

6. comparing the density of mutans streptococci and lactobacilli colonies with the corresponding evaluation pictures in the enclosed model chart (Fig. 1).

Fig. 1. Prevalence of MS bacteria in 2-3-4-5-year-olds in the investigated group.

CRT test is used to determine the mutans streptococci and lactobacilli count in saliva by means of selective culture media. Findings of 1 mln CFU or more of MS or LB per ml saliva indicate a high caries risk.

RESULTS

In the investigated group 33 children were caries-free, 42 of them had caries. Mean dmft according to the age was as follows: 0.33, 2.75, 4.46, 4.68. Total mean dmft for the hole group was 3.12 (Tab. 1).

High level of mutans streptococci were present in 51 (68%) cases, 24 (32%) of them were free from the bacteria. Lactobacilli were present in the saliva of 35 (46%) children, so in 40 (54%) children the bacteria was not present.

In the group of caries-free children, 51.5% were highly infected by MS (17 children) and 30.3% of them had high level of LB (10 children). In the group of chi

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