title: [Distribution of Bifidobacterium in oral cavities of children and the relations with caries].
abstract: OBJECTIVE
  To explore a selected-media of Bifidobacterium from oral cavity, to detect the distribution of Bifidobacterium in different sites of children and primarily investigate the relationship between oral Bifidobacterium and early childhood caries.
  
  
  METHODS
  70 children aged from 3 to 5-year-old were selected, 30 children were caries-free and 40 were severe early childhood caries (S-ECC). Saliva was collected and plaque samples from the 30 healthy subjects were pooled. For S-ECC group, plaques were collected separately from four different sites as follows: Saliva, surfaces of intact enamel, surfaces of white spot-lesions, and deep dentin-lesions. Samples would be grown in the selected-media, and the whole DNA of bacteria was extracted. Polymerase chain reaction was performed with specific primers and the results were analyzed by the electrophoresis.
  
  
  RESULTS
  Bifidobacterium were detected 0 in the caries-free children, while 47.5% in the S-ECC group. There was significant difference between two groups (P < 0.05) and there was no difference between different sites of teeth in S-ECC group (P > 0.05). 27.5% Bifidobacterium were detected in saliva, 27.5% on surfaces of intact enamel, 20.0% on surfaces of white spot-lesions and 22.5% in deep dentin-lesions. 10% Bifidobacterium dentium were detected in saliva, 7.5% on surfaces of intact enamel, 7.5% on surfaces of white spot-lesions and 10.0% in deep dentin-lesions.
  
  
  CONCLUSIONS
  One type of modified selected media of Bifidobacterium in oral cavity was explored. Bifidobacterium may be related to the occurrence of the S-ECC and has nothing to do with different sites of teeth in children.
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China.
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Zhai
authors.forename: Jing
authors.initials: J
authors.lastname: Zou
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Lu
mesh_terms: D001419:Bacteria; D001644:Bifidobacterium; D002648:Child; D002675:Child, Preschool; D003731:Dental Caries; D003743:Dental Enamel; D003773:Dental Plaque; D003804:Dentin; D006801:Humans; D016133:Polymerase Chain Reaction; D012463:Saliva; D014070:Tooth