title: In vitro color evaluation of esthetic coatings for metallic dental implants and implant prosthetic appliances.
abstract: OBJECTIVE
  The aim of this study was to characterize the optical properties of newly developed esthetic coatings for metallic implants and components for an improved peri-implant soft tissue appearance.
  
  
  METHODS
  Pig maxillae (n = 6) were used for the in vitro color evaluation of coated and uncoated samples. Three different coating systems (Ti-ZrO(2), Ti-Al-ZrO(2), and Ti-Ag-ZrO(2)) were deposited on titanium substrates, which exhibited different roughness (polished, machined, and sand-blasted) and interference colors (pink, yellow, and white). Spectrophotometric measurements were made of samples below three different mucosa thicknesses (1 mm, 2 mm, and 3 mm) and titanium served as negative control. Color difference ΔE was calculated using ΔL, Δa, and Δb values for each sample (in total 30 samples).
  
  
  RESULTS
  ΔE values were significantly above the threshold value of 3.70 for sand-blasted Ti and Ti-ZrO(2) samples when tested below 1 mm thick soft tissue, hence resulted in a dark appearance of the soft tissues. In contrast, Ti-Al-ZrO(2) and Ti-Ag-ZrO(2) samples showed significant ΔL values below 1 mm, which indicates a brightening of the covering tissue. In general, ΔE values decreased with increasing thickness of the tissue. At 3 mm thick tissue, ΔE values were significantly below 3.70 for Ti-Al-ZrO(2) and Ti-Ag-ZrO(2) samples. The preferable substrate surface should be machined due increased color brightness, good soft tissue integration and improved adhesion between coating and substrates. Improvement of the optical appearance of the metal was achieved with the coating systems Ti-Al-ZrO(2) and Ti-Ag-ZrO(2). Darkening effects could not be observed for these systems, and partially light brightening of the tissue was observed. Advantageous colors were suggested to be pink and yellow.
authors.affiliation: Department of Materials, Laboratory for Nanometallurgy, ETH Zurich, Zürich, Switzerland.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Pecnik
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Roos
authors.forename: Daniel
authors.initials: D
authors.lastname: Muff
authors.forename: Ralph
authors.initials: R
authors.lastname: Spolenak
authors.forename: Irena
authors.initials: I
authors.lastname: Sailer
mesh_terms: D000535:Aluminum; D000818:Animals; D020099:Coated Materials, Biocompatible; D003116:Color; D015921:Dental Implants; D017267:Dental Prosthesis Design; D066298:In Vitro Techniques; D008422:Materials Testing; D017797:Prosthesis Coloring; D012834:Silver; D013499:Surface Properties; D013552:Swine
chemical_list: D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D012834:Silver; D000535:Aluminum
keywords: Prosthodontics; biomaterials; material sciences