title: [Effect of tea polyphenol on the demineralization and remineralization of enamel in vitro].
abstract: OBJECTIVE
  To investigate the effect of tea polyphenol (TP) on the mineralization behaviour of enamel in two sterile, in vitro systems.
  
  
  METHODS
  In the demineralization study, sound enamel sections were pH-cycled. Treatments were 2000 mg/L TP, 200 mg/L TP, 2000 mg/L TP + 100 mg/L fluoride, 100 mg/L fluoride, and deionized water. In the remineralization study, surface-softened enamel was used and pH-cycled as above. Test treatments were 2000 mg/L TP, 2000 mg/L TP + 250 mg/L fluoride, 250 mg/L fluoride, and deionized water. The acidic buffers were retained for calcium analysis. The enamel was analysed before and after pH-cycling by microhardness.
  
  
  RESULTS
  In the demineralization study, the calcium depletion rates(CDR) were (0.43 +/- 0.05), (0.49 +/- 0.006), (0.21 +/- 0.02), (0.21 +/- 0.03) and (0.50 +/- 0.11) microgram/(mm2.h) respectively. The Knoop hardness values(KHV) percent reduction were 94.19 +/- 3.50, 96.62 +/- 0.63, 74.74 +/- 4.09, 77.79 +/- 3.11 and 97.32 +/- 4.03 respectively. There were no significant differences within either the TP-only groups or the fluoride groups, but the fluoride groups were significantly more efficacious than the TP-only groups (P < 0.05). In the remineralization study, the KHV percent increase were -11.96 +/- 10.1, -21.32 +/- 11.3, -49.52 +/- 24.6 and -4.24 +/- 8.51 respectively. Notably more remineralization was observed in the fluoride group. There were no significant differences between the other groups (P > 0.05).
  
  
  CONCLUSIONS
  The data of this in vitro study suggest that TP has no effect on de/remineralization of enamel blocks and there is no synergetic action of TP and fluoride in a sterile system. This finding supports the proposition that tea polyphenols exert an anti-caries effect via an anti-microbial mode-of-action.
authors.affiliation: West China School of Stomatology, Sichuan University, Chengdu 610041, China.
authors.forename: Ji-yao
authors.initials: JY
authors.lastname: Li
authors.forename: Ling
authors.initials: L
authors.lastname: Zhan
authors.forename: J
authors.initials: J
authors.lastname: Barlow
authors.forename: R J
authors.initials: RJ
authors.lastname: Lynch
authors.forename: Xue-dong
authors.initials: XD
authors.lastname: Zhou
authors.forename: Tian-jia
authors.initials: TJ
authors.lastname: Liu
mesh_terms: D000818:Animals; D002417:Cattle; D003731:Dental Caries / Q000517:prevention & control; D003743:Dental Enamel / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology*; D010636:Phenols / Q000494:pharmacology*; D059808:Polyphenols; D013662:Tea / Q000737:chemistry*; D017001:Tooth Demineralization; D014089:Tooth Remineralization
chemical_list: D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D013662:Tea