[Quantitative analysis of streptococcus mutans and its proportion in the dental plaque of different caries-susceptible children].
OBJECTIVE
To determine the quantity of Streptococcus mutans (S. mutans) and the ratio of S. mutans to total bacteria in the dental plaque of different caries-susceptible children.


METHODS
Dental plaque samples from 26 children aged 3 years old to 4 years old were collected. The quantities of S. mutans and total bacteria were determined by TaqMan real-time fluorescence quantitative polymerase chain reaction (PCR). The ratio ofS. mutans to total bacteria in children with and without caries was calculated and statistically analyzed.


RESULTS
In children with and without caries, the quantities of S. mutans were 1.33 x 10(5) and 1.16 x 10(3) CFU x mg(-1), the total bacteria were 7.17 x 10(7) and 1.01 x 10(8) CFU x mg(-1), and the ratios of S. mutans to total bacteria were 0.058 6 and 0.018 6, respectively. Significant differences were observed in the quantities of S. mutans and the total bacteria as well as in the ratios of S. mutans to total bacteria of the two groups (P = 0.033, 0.418, 0.008).


CONCLUSIONS
The quantities of total bacteria of the two groups show negligible difference. However, the quantity of S. mutans and the ratio of S. mutans to total bacteria in caries-susceptible children are higher than those in caries-free children. Therefore, the ratios of S. mutans to total bacteria in plaque are closely associated with the prevalence of dental caries in children.
Dept. of Preventive Dentistry, The Affiliated Hospital of Stomatology, Chongqing Medical University, Chongqing Key Laboratory for Oral Disease and Biomedical Sciences, Chongqing 400015, China.
Hechuan
H
Zhao
Dept. of Preventive Dentistry, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Xiaochi
X
Chen
Dept. of Preventive Dentistry, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Tao
T
Xu
D001419:Bacteria; D002675:Child, Preschool; D003731:Dental Caries; D003773:Dental Plaque; D006801:Humans; D015995:Prevalence; D013295:Streptococcus mutans