title: Clinical performance of a newly developed spectrophotometric system on tooth color reproduction.
abstract: BACKGROUND
  Matching a natural maxillary central incisor to a metal ceramic crown is one of the most difficult challenges in clinical dentistry due to the limitations of dental shade guides and the subjectivity of perceptual evaluation.
  
  
  OBJECTIVE
  The purpose of this study was to assess the clinical effectiveness of a spectrophotometric shade-matching system on tooth color reproduction.
  
  
  METHODS
  Two metal ceramic crowns were fabricated for a maxillary central incisor for 36 patients using 2 shade-matching techniques. The first technique was conventional visual matching using 3 shade guide systems, and the second was an instrument-based color-matching technique using a new spectrophotometric system. Color difference (DeltaE) values between the contralateral natural tooth and each of the 2 crowns were calculated in the cervical, middle, and incisal regions. The DeltaE values were compared using a Student's t test (alpha=.05). Three calibrated examiners evaluated the color match by ranking it from 1 to 10 (10 = perfect match; 1 = no match; < or =8, accepted; > or =7, rejected). McNemar's test was used to calculate the odds ratio of accepting restorations fabricated using a spectrophotometric system to conventional methods.
  
  
  RESULTS
  Results revealed that the mean DeltaE values of crowns matched with the spectrophotometer were significantly lower than those using a conventional technique (P<.001). The odds ratio of 12.5 was calculated, indicating that conventionally matched crowns were more likely to be rejected than those matched using the spectrophotometer (P<.001).
  
  
  CONCLUSIONS
  In this clinical study, crowns fabricated using a dedicated spectrophotometer had a significantly better color match and a lower rate of rejection due to shade mismatch compared to crowns fabricated with a conventional shade-matching method.
authors.affiliation: Instructor, Department of Oral Health Policy and Epidemiology, Harvard School of Dental Medicine, Boston, Mass.
authors.forename: John D
authors.initials: JD
authors.lastname: Da Silva
authors.forename: Sang E
authors.initials: SE
authors.lastname: Park
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Weber
authors.forename: Shigemi
authors.initials: S
authors.lastname: Ishikawa-Nagai
mesh_terms: D000328:Adult; D003116:Color; D003118:Color Perception; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design / Q000295:instrumentation / Q000379:methods*; D003800:Dental Technicians; D005260:Female; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology*; D008297:Male; D016876:Metal Ceramic Alloys / Q000737:chemistry; D008875:Middle Aged; D017797:Prosthesis Coloring / Q000295:instrumentation / Q000379:methods*; D011476:Prosthodontics; D013053:Spectrophotometry / Q000295:instrumentation / Q000379:methods*; D019237:Tooth Cervix / Q000033:anatomy & histology; D019228:Tooth Crown / Q000033:anatomy & histology
chemical_list: D016876:Metal Ceramic Alloys; D003776:Dental Porcelain