title: Quantifying and qualifying surface changes on dental hard tissues in vitro.
abstract: BACKGROUND
  Tooth surface loss (TSL) is an increasingly recognised problem. We are therefore seeing an increase in the number and complexity of in vitro studies investigating factors that modify effects at the tooth surface.
  
  
  OBJECTIVE
  The aim of this paper is to provide a narrative review that illustrates the more commonly used in vitro methods (both historical and contemporaneous) that are available for measuring surface loss and surface change.
  
  
  METHODS
  An initial search (March 2009) was carried out using Scopus abstract and citation database with the keywords 'dental' AND 'erosion OR abrasion' AND 'surface change OR surface loss' AND 'vitro' (1975-2009). This resulted in 69 papers which were reviewed and the methods critically appraised. Bibliographic material from the papers was then used in order to find other appropriate sources.
  
  
  RESULTS
  It is clear that tooth surface change is a complex process that can be measured in a variety of ways. No single technique provides a comprehensive assessment of the remaining tooth surface, and each technique suffers its own limitations. What is also clear is that way in which surface change is reported by each of the techniques gives little information relating to how the surface may change in the immediate future.
  
  
  CONCLUSIONS
  Despite a variety of available in vitro tests for measuring surface changes, the roughness average (R(a)) is still the main reported measurement within dental studies. Using the same set of profilometric data, it is proposed that additionally reporting bearing area parameters will allow a further and more meaningful description of the surface quality.
authors.affiliation: School of Dental Sciences, Newcastle University, Framlington Place, Newcastle-upon-Tyne, Tyne and Wear NE2 4BW, United Kingdom. james.field@ncl.ac.uk
authors.forename: J
authors.initials: J
authors.lastname: Field
authors.forename: P
authors.initials: P
authors.lastname: Waterhouse
authors.forename: M
authors.initials: M
authors.lastname: German
mesh_terms: D000818:Animals; D003745:Dental Enamel Permeability; D003806:Dentin Permeability; D005453:Fluorescence; D006801:Humans; D066298:In Vitro Techniques; D007368:Interferometry; D007834:Lasers; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008859:Microscopy, Polarization; D036103:Nanotechnology; D013499:Surface Properties; D057085:Tooth Wear / Q000473:pathology*