In vitro color evaluation of esthetic coatings for metallic dental implants and implant prosthetic appliances

ObjectivesThe 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. Material and methodsPig maxillae (n=6) were used for the in vitro color evaluation of coated and uncoated samples. Three different coating systems (Ti-ZrO2, Ti-Al-ZrO2, and Ti-Ag-ZrO2) 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 (1mm, 2mm, and 3mm) and titanium served as negative control. Color difference E was calculated using L, a, and b values for each sample (in total 30 samples). ResultsE values were significantly above the threshold value of 3.70 for sand-blasted Ti and Ti-ZrO2 samples when tested below 1 mm thick soft tissue, hence resulted in a dark appearance of the soft tissues. In contrast, Ti-Al-ZrO2 and Ti-Ag-ZrO2 samples showed significant L values below 1mm, which indicates a brightening of the covering tissue. In general, E values decreased with increasing thickness of the tissue. At 3 mm thick tissue, E values were significantly below 3.70 for Ti-Al-ZrO2 and Ti-Ag-ZrO2 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-ZrO2 and Ti-Ag-ZrO2. 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.