title: [Influence of Coca-Cola on early erosion and surface microhardness of human enamel: an in situ study].
abstract: OBJECTIVE
  Assessed the effect of single dose attack of Coca-Cola on early erosion and surface microhardness of permanent human enamel, in order to provide diet instructions on minimum amount and frequency of carbonated beverage consumption.
  
  
  METHODS
  Eighty enamel slabs were prepared out of 10 extracted human mandibular third molars, and distributed into 8 groups with randomized block design(n=10). Ten generally healthy volunteers with normal saliva secretion wore acrylic palatal appliances containing 2 enamel slabs, with formation of a salivary pellicle 2 h ahead. The volunteers were instructed to drink 100 ml fresh Coca-Cola within 20 s. And then the alterations of the enamel slabs were measured using a Vicker's microhardness tester at 1, 2, 4, 6, 8, 10, 20 and 30 min after the consumption of Coca-Cola. For each volunteer, the experiment was carried out in four days, 2 samples were examined each time. Data were analyzed using Kruskal-Wallis and Wilcoxon tests(α =0.05).
  
  
  RESULTS
  Significant decreases in surface microhardness(SMH)were observed in each time point(P<0.01). The percentages of surface microhardness changes on each exposure time were(12.2±3.9)%,(16.8±5.5)%,(16.7±5.6)%,(16.2±6.2)%,(16.6±9.0)%,(15.6±3.7)%,(13.8±4.8)% and(11.4±3.2)%, respectively. Significant differences were observed between G1 min and G2-8 min(P=0.029), G2-8 min and G30 min(P=0.008).
  
  
  CONCLUSIONS
  Single intake of 100 ml Coca-Cola could lead to significant decrease of enamel microhardness and initiate erosion of enamel surface. Enamel surface microhardness decreased to the lowest points at 2-8 min, and began to recover after 10 min. The enamel surface microhardness could not fully recovered to the baseline level in 30 min if no intervention was performed.
authors.affiliation: The 4th Dental Clinic, Peking University School and Hospital of Stomatology, Beijing 100025, China.
authors.forename: M
authors.initials: M
authors.lastname: Yuan
authors.affiliation: The 4th Dental Clinic, Peking University School and Hospital of Stomatology, Beijing 100025, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: X J
authors.initials: XJ
authors.lastname: Gao
mesh_terms: D002253:Carbonated Beverages / Q000009:adverse effects*; D003743:Dental Enamel / Q000187:drug effects*; D006244:Hardness / Q000187:drug effects; D006245:Hardness Tests; D006801:Humans; D008964:Molar, Third / Q000187:drug effects; D011897:Random Allocation; D018709:Statistics, Nonparametric; D014077:Tooth Erosion / Q000139:chemically induced*