title: Color effects of gingiva on cervical regions of all-ceramic crowns.
abstract: BACKGROUND
  The final color of all-ceramic crowns is influenced by the color of both the remaining tooth structure and the surrounding gingival tissue. The optical effects of gingival tissue on an all-ceramic crown have never been fully studied.
  
  
  OBJECTIVE
  The purpose of this study is to investigate the effects of gingival color on ceramic crowns in the cervical region. materials and methods: Thirty-one all-ceramic crowns of differing shades were included in this study. Using a spectrophotometer, the color values of each crown were measured on a typodont in the absence of an artificial gingiva (control group) and in the presence of an artificial gingiva (test group). CIELAB color coordinates (L*, a*, b*) were collected from three regions of the cervical area in descending order from the gingival margin (upper region, middle region, and lower region). Color difference values (ΔE*) were calculated for each cervical region between the test and control groups. ΔE* between the test and control groups from the upper to lower cervical regions was also compared with each other. The statistical analysis was performed using the student t-test and one-way analysis of variance (ANOVA) test.
  
  
  RESULTS
  The mean ΔE* values between the test group and control group at the upper, middle, and lower cervical regions were 5.8, 2.8, and 1.8, respectively. Significant color differences between the test and control group were detected in all three incremental regions (p < 0.001 at ΔE* = 1.6 threshold), with all color coordinates (L*, a*, and b*) contributing significantly to the color differences in these regions (p < 0.001). The color variations in the cervical area also varied significantly from the upper region to the lower region, with L* and a* contributing most to the differences.
  
  
  CONCLUSIONS
  The presence of artificial gingiva is a critical factor in precise color matching and color reproduction for all-ceramic crowns.
  
  
  CONCLUSIONS
  Gingival tissue has significant optical effects on the color of all-ceramic crowns at the cervical areas; therefore, it is suggested that artificial gingiva be used by both dentists and ceramists while matching and replicating tooth color with ceramic restorations. (J Esthet Restor Dent ••:••-••, 2012).
authors.affiliation: Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, MA, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Lin
authors.forename: Alison
authors.initials: A
authors.lastname: Seliger
authors.forename: Mindy
authors.initials: M
authors.lastname: Gil
authors.forename: John D
authors.initials: JD
authors.lastname: da Silva
authors.forename: Shigemi
authors.initials: S
authors.lastname: Ishhikawa-Nagai
mesh_terms: D003116:Color; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry*; D005881:Gingiva / Q000033:anatomy & histology*; D006801:Humans; D017797:Prosthesis Coloring; D013053:Spectrophotometry / Q000295:instrumentation; D019237:Tooth Cervix / Q000033:anatomy & histology; D015040:Zirconium / Q000737:chemistry
chemical_list: D003764:Dental Materials; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide