title: Direct measurement of stain retention in third molars.
abstract: OBJECTIVE
  To directly determine the mass of dye retained in teeth following exposure to aqueous solutions of Rhodamine B and to correlate tooth color modifications.
  
  
  METHODS
  Extracted third molars (25) were selected and sectioned at the cementoenamel junction for coronal staining. Pulp tissue was removed and teeth sonicated to remove debris. Teeth were kept in deionized water for 12 hours and subsequently weighed. They were then stained for 4 hours in 5 ml of Rhodamine B dye at two different concentrations. The samples were then subjected to two 8 hours rinses in deionized water. The tooth shade was recorded with a commercially available intraoral spectrophotometer (Vita Easyshade Compact, Vita Zahnfabrik, Bad Säckingen, Germany) at baseline (T1), after dye immersion (T2), and after water rinsing (T3). A standard absorption curve was then used to calculate the dye mass in the rinse solutions as well as the post- treatment stain solutions. All solution optical absorption curves were recorded using a laboratory research spectrophotometer (Cary 300, Agilent, USA). The mass of dye in each solution was then calculated from the standard curve relating optical absorption to aqueous dye concentration.
  
  
  RESULTS
  An average change in the CIE (a) values of 8.0 ± 0.3 were observed for concentrations of Rhodamine B similar to the optical appearance of wine or other darkly colored juices while an increase of 10× in concentration gave values too high to measure using a standard intraoral spectrophotometer. By measuring the optical absorbance of the staining solutions before and after the staining process, we were able to measure dye retention of 54 ± 26 micrograms per gram of tooth.
  
  
  CONCLUSIONS
  While no significant correlation could be found between the amount of stain retention in the dentition and the tooth shade due to the high uncertainties in the spectroscopic measurements, we were able to show that this method should admit such comparisons for future research.
  
  
  CONCLUSIONS
  The development of a reliable chromophore infiltration model may provide standardized and reproducible results in evaluating tooth whitening efficacy.
authors.affiliation: Associate Professor and Director, Biomaterials and Photonics Research Laboratory, Loma Linda University School of Dentistry, 11092 Anderson St. Loma Linda, CA 92350, USA, Phone: (909) 558-0656 Fax: (909) 558-0270, e-mail: skurti@llu.edu.
authors.forename: R Steven
authors.initials: RS
authors.lastname: Kurtir
authors.affiliation: Research Volunteer, Department of Restorative Dentistry, Center for Dental Research, Loma Linda University School of Dentistry, 11092 Anderson St. Loma Linda, CA 92350, USA.
authors.forename: Berj Der
authors.initials: BD
authors.lastname: Boghossian
authors.affiliation: Associate Professor, Department of Operative Dentistry, University of Iowa College of Dentistry, Iowa city, IA, USA.
authors.forename: So Ran
authors.initials: SR
authors.lastname: Kwon
mesh_terms: D065966:Absorption, Physicochemical; D003116:Color; D005456:Fluorescent Dyes / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D006801:Humans; D007101:Immersion; D008964:Molar, Third / Q000378:metabolism*; D012235:Rhodamines / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D013053:Spectrophotometry / Q000295:instrumentation; D013997:Time Factors; D019228:Tooth Crown / Q000378:metabolism; D014075:Tooth Discoloration / Q000145:classification* / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D012235:Rhodamines; D014867:Water; C029773:rhodamine B