title: An in situ model to study the toothpaste abrasion of enamel.
abstract: OBJECTIVE
  In order to understand the clinical relevance of dentifrice abrasivity on the dentition in vivo, an in situ enamel wear model has been developed.
  
  
  METHODS
  Polished human enamel blocks were indented with a Knoop diamond, attached to dentures and worn by adult volunteers for 24 h per day. The blocks were brushed for 30 s, twice per day with dentifrices of known relative dentine abrasivity (RDA) and relative enamel abrasivity (REA). The dentifrices used were either dentifrice A (RDA=85, REA=3.4), dentifrice B (RDA=189, REA=2.0) or dentifrice C (RDA=132, REA=42.7). After 28 days, the blocks were removed and the geometry of each Knoop indent was remeasured. From the baseline and post-treatment values of indent length, the amount of enamel wear was calculated from the change in the indent depth.
  
  
  RESULTS
  The median values for enamel wear of dentifrices A, B and C were -0.02, 0.01 and -0.48 microm, respectively. The differences between dentifrice C and dentifrices A and B were of statistical significance.
  
  
  CONCLUSIONS
  This study has demonstrated the usefulness of an in situ technique for investigating the relationship between the abrasivity of a dentifrice in vitro and the wear of enamel in situ.
authors.affiliation: Unilever Oral Care, Port Sunlight Laboratory, Merseyside, UK. andrew.joiner@unilever.com
authors.forename: Andrew
authors.initials: A
authors.lastname: Joiner
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Pickles
authors.forename: Carolyn
authors.initials: C
authors.lastname: Tanner
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Weader
authors.forename: Peter
authors.initials: P
authors.lastname: Doyle
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D003743:Dental Enamel / Q000473:pathology*; D003802:Dentifrices / Q000009:adverse effects / Q000145:classification; D003804:Dentin / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D000091402:Prohibitins; D014072:Tooth Abrasion / Q000209:etiology*; D014099:Toothbrushing / Q000295:instrumentation; D014100:Toothpastes / Q000009:adverse effects* / Q000145:classification
chemical_list: D003802:Dentifrices; C000717331:PHB2 protein, human; D000091402:Prohibitins; D014100:Toothpastes