title: Relationship between laser fluorescence and enamel hypomineralisation.
abstract: OBJECTIVE
  To study the relation between the mechanical properties of hypomineralised enamel, and its laser fluorescence (LF).
  
  
  METHODS
  Five extracted teeth with molar-incisor hypomineralisation (MIH) were sectioned longitudinally through the defects and polished to prepare the hypomineralised enamel for testing. Hardness (H) and elastic modulus (E) of enamel were measured using nanoindentation. Measurement recording started from the cervicoenamel junction and proceeded occlusally in increments of 200 microm. Laser fluorescence readings were taken along the same line and at the same sites using a DIAGNOdent pen.
  
  
  RESULTS
  H, E, and LF readings from cervical enamel were within the expected range for normal sound enamel. After log transformation of the H and E measurements to allow for linear correlation analysis, there was a significant and moderately strong inverse correlation between LF and H or E samples (r (between specimens)=0.59, r (between specimens)=0.39, respectively; p<0.001).
  
  
  CONCLUSIONS
  This study shows that, in the absence of dental caries, increased DIAGNOdent readings can indicate enamel hypomineralisation. While the increased LF readings in carious enamel are thought to be related to the presence of caries bacterial metabolites, the increased readings in hypomineralised enamel may be related to proteins in the hypomineralised enamel and/or light scattering by the inhomogeneous enamel.
authors.affiliation: Department of Oral Sciences, Faculty of Dentistry, University of Otago, New Zealand. farra304@student.otago.ac.nz
authors.forename: R A
authors.initials: RA
authors.lastname: Farah
authors.forename: B K
authors.initials: BK
authors.lastname: Drummond
authors.forename: M V
authors.initials: MV
authors.lastname: Swain
authors.forename: S
authors.initials: S
authors.lastname: Williams
mesh_terms: D003732:Dental Caries Activity Tests / Q000295:instrumentation*; D003743:Dental Enamel / Q000473:pathology* / Q000528:radiation effects; D003744:Dental Enamel Hypoplasia / Q000175:diagnosis* / Q000473:pathology; D055119:Elastic Modulus; D005453:Fluorescence; D006244:Hardness; D006801:Humans; D007834:Lasers; D008963:Molar; D012720:Severity of Illness Index; D019237:Tooth Cervix / Q000473:pathology / Q000528:radiation effects; D019228:Tooth Crown / Q000473:pathology* / Q000528:radiation effects; D017001:Tooth Demineralization / Q000175:diagnosis* / Q000473:pathology