title: The effect of acidic beverages on the ultrastructure of the acquired pellicle--an in situ study.
abstract: OBJECTIVE
  The aim of the present in situ study was to investigate ultrastructural alterations as well as protective properties of the pellicle layer during consumption of acidic beverages.
  
  
  METHODS
  Bovine enamel slabs were fixed on buccal and palatal aspects of individual splints and exposed in the oral cavities of three subjects for 120 min. In the following, the subjects drank orange juice, coke light or sprite light. Half of the specimens were removed afterwards, the others were exposed to the oral fluids for another 120 min. Erosive alterations of the bovine enamel slabs were measured by determination of the Knoop-micro-hardness. In addition, the ultrastructure of the pellicle was evaluated by transmission electron microscopy (TEM).
  
  
  RESULTS
  Determination of Knoop-micro-hardness yielded only little reduction of the relative Knoop-hardness in situ during consumption of sprite light (-0.053+/-0.019) and coke light (-0.075+/-0.04). With orange juice nearly no change of the hardness was recorded. TEM-pictures showed that the globular outer layers of the pellicle were removed to a different extent according to the localisation of the specimens in the oral cavity, whereas the basal pellicle was not affected by the acidic beverages. On the specimens carried for another 120 min after the erosive attack, lacunae filled with organic structures were observed underneath the basal side of the pellicle.
  
  
  CONCLUSIONS
  During fast consumption of acidic beverages in situ, the erosive effects on pellicle coated bovine enamel are moderate and juices seem to be less harmful as compared with low pH soft drinks. Pellicle proteins in eroded lacunae may impact the remineralization process.
authors.affiliation: Department of Operative Dentistry and Periodontology, University of Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Hannig
authors.forename: D
authors.initials: D
authors.lastname: Berndt
authors.forename: W
authors.initials: W
authors.lastname: Hoth-Hannig
authors.forename: M
authors.initials: M
authors.lastname: Hannig