title: The use of in situ models and QLF for the study of coronal caries.
abstract: OBJECTIVE
  The purpose of the paper is to review aspects of the systems available to model the caries process in enamel.
  
  
  METHODS
  The in situ model developed in Liverpool, and the new method of quantifying mineral loss, Quantitative Light-induced Fluorescence (QLF), are described. QLF is a powerful new diagnostic tool which can be used to measure demineralisation and remineralisation in tooth surfaces in vivo; studies to optimise, validate and use QLF in different clinical situations are described.
  
  
  RESULTS
  Examples of the use of in situ models show that they are particularly valuable for monitoring de and remineralisation of artificial lesions in relation to product testing as alternatives to clinical trials, and present significant advances over in vitro methods. Quantification of mineral loss by Transverse Microradiography (TMR) as in the traditional Liverpool model has produced much valuable information, but the destructive nature of the method limits experimental design, and removes the system from the clinical situation. As a possible alternative, QLF has been validated and optimised. Longitudinal measures can be made on the same surface, and examples of its use are for monitoring recurrent caries and demineralisation around orthodontic brackets.
  
  
  CONCLUSIONS
  While current in situ models provide a major advance over earlier caries models, measurement of de and remineralisation by destructive methods such as transverse microradiography limits the design of experimental investigations. QLF offers significant time saving, reduces the cost of clinical studies, and because the measurements can be carried out longitudinally in vivo, can remove the need for intra-oral appliances carrying experimental tissues.
authors.affiliation: Cariology Research Group, Department of Clinical Dental Sciences, School of Dentistry, The University of Liverpool, Edwards Building, Daulby Street, Liverpool L69 3GN, UK. s.m.higham@liv.ac.uk
authors.forename: S M
authors.initials: SM
authors.lastname: Higham
authors.forename: I A
authors.initials: IA
authors.lastname: Pretty
authors.forename: W M
authors.initials: WM
authors.lastname: Edgar
authors.forename: P W
authors.initials: PW
authors.lastname: Smith
mesh_terms: D003731:Dental Caries / Q000175:diagnosis* / Q000378:metabolism*; D003732:Dental Caries Activity Tests / Q000295:instrumentation*; D003743:Dental Enamel / Q000378:metabolism* / Q000473:pathology; D005453:Fluorescence; D006801:Humans; D008027:Light; D008852:Microradiography / Q000379:methods; D008954:Models, Biological; D015203:Reproducibility of Results; D019228:Tooth Crown / Q000378:metabolism / Q000473:pathology; D017001:Tooth Demineralization / Q000473:pathology; D014089:Tooth Remineralization