title: A comparison of in vitro erosion-like mineral loss between continuous and intermittent acidic exposure with and without human saliva.
abstract: OBJECTIVE
  This in vitro study aimed to compare erosion-like mineral loss following intermittent or continuous acidic exposures, and considered the role that human saliva may play.
  
  
  METHODS
  180 bovine enamel blocks were divided randomly into four equally-sized groups and exposed to one of the 4 protocols 6 times daily over 6 days (total acidic exposure time of 6h): Group 1, continuous 10 min in orange juice (OJ) followed by 10 min in deionised water; Group 2, continuous 10 min in OJ followed by 10 min in stimulated saliva; Group 3, ten 1-min OJ exposures alternating with ten 1-min deionised water exposures; Group 4, ten 1-min OJ exposures alternating with ten 1-min stimulated saliva exposures. Specimens were stored in a remineralising solution between acidic exposures. Sections were cut and transverse microradiography was used to measure lesion depth in each specimen.
  
  
  RESULTS
  Mean (sd) lesion depths were 21.5 (8.1), 21.2 (6.2), 81.7 (12.2) and 72.8 (12.4) μm for Groups 1-4, respectively. Significant differences existed between all protocols except Groups 1 and 2 (mean difference -0.3 μm, 95% CI: -6.1 to 5.5). The mean difference between Groups 3 and 4 was 8.9 μm (95% CI: 3.2-14.7).
  
  
  CONCLUSIONS
  Repeated, intermittent exposure to an acidic drink in vitro resulted in greater lesion depth than a continuous exposure of the same duration. Saliva offered some protection against intermittent acidic exposure.
authors.affiliation: Peninsula Dental School, Peninsula College of Medicine and Dentistry, The University of Plymouth, Room C407, Portland Square, Plymouth PL4 8AA, United Kingdom. stephen.creanor@pds.ac.uk
authors.forename: Stephen
authors.initials: S
authors.lastname: Creanor
authors.forename: Siobhan
authors.initials: S
authors.lastname: Creanor
authors.forename: Nutayla
authors.initials: N
authors.lastname: Alharthy
mesh_terms: D000143:Acids; D000818:Animals; D001628:Beverages / Q000009:adverse effects; D002122:Calcium Chloride / Q000494:pharmacology; D002417:Cattle; D032084:Citrus sinensis; D003743:Dental Enamel / Q000473:pathology; D005638:Fruit; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007091:Image Processing, Computer-Assisted; D008852:Microradiography; D010756:Phosphoric Acids / Q000494:pharmacology; D011897:Random Allocation; D012463:Saliva / Q000502:physiology*; D013997:Time Factors; D014077:Tooth Erosion / Q000209:etiology* / Q000473:pathology; D014089:Tooth Remineralization; D014867:Water / Q000737:chemistry
chemical_list: D000143:Acids; D010756:Phosphoric Acids; D014867:Water; C030242:phosphoric acid; D002122:Calcium Chloride