title: Opalescence of dental porcelain enamels.
abstract: OBJECTIVE
  The objective of this study was to compare the microstructures of teeth, natural opals, and opal dental enamel porcelains to examine the mechanisms that cause opalescence.
  
  
  METHODS
  Four dental porcelains, a natural opal mineral, and a human tooth were examined. Replicas were assessed in transmission electron microscopy for features that would cause opalescence. Enamel dental porcelains denoted as "light" were selected for the study. X-ray diffraction and color analyses of the porcelains were also performed.
  
  
  RESULTS
  All the materials were opalescent, to varying degrees. The porcelains with fewer microscopic features were less opalescent. The presence of dispersed particles or a phase-separated glass was found to cause opalescence in dental porcelains.
  
  
  CONCLUSIONS
  A phase-separated glass in one enamel porcelain best resembled the microstructure of natural opal mineral and teeth, and this was the most "opalescent" material.
authors.affiliation: Ceramco Dentsply, Burlington, New Jersey, USA. cprimus@mac.com
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Primus
authors.forename: Christopher C Y
authors.initials: CC
authors.lastname: Chu
authors.forename: James E
authors.initials: JE
authors.lastname: Shelby
authors.forename: Eugenio
authors.initials: E
authors.lastname: Buldrini
authors.forename: Christine E
authors.initials: CE
authors.lastname: Heckle
mesh_terms: D000465:Algorithms; D003116:Color; D003460:Crystallization; D003743:Dental Enamel / Q000737:chemistry / Q000648:ultrastructure; D003776:Dental Porcelain / Q000737:chemistry*; D005898:Glass / Q000737:chemistry; D006801:Humans; D008027:Light; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D055095:Optics and Photonics; D010316:Particle Size; D012031:Refractometry; D012822:Silicon Dioxide / Q000737:chemistry; D013053:Spectrophotometry; D014961:X-Ray Diffraction
chemical_list: D003776:Dental Porcelain; D012822:Silicon Dioxide