[Various kinds of glossiness of Au-Ag-Cu alloys with different surface finishes]

Nine experimental Au-Ag-Cu alloys with different surface finishes were measured for various kinds of glossiness using a digital variable gloss meter. Eight different methods of measurement for glossiness were chosen from the ones described in Japanese Industrial Standard Z 8741-1962. In addition to glossiness, color coordinates in the CIELAB color scale and surface roughness were measured. The compositions of the alloys were 40, 50, or 60 at% gold, 0, 20, or 40 at% copper, and 0-60 at% silver (balance). This study was initiated to collect fundamental data necessary to determine the most appropriate characteristic which could express the degree of tarnishing of various dental alloys independently of their own colors and compositions. Only one type of contrast glossiness based on two different receptor apertures with an incident angle of 60 degrees could demonstrate statistically significant differences between all the combinations of the different surface conditions analyzed. Effects of compositions on the values of various kinds of glossiness and color coordinates of the alloys with highly polished surfaces were statistically significant except contrast glossiness of different receptor apertures. Specular gloss and contrast gloss were considered to be as inappropriate as color of total reflected light in measuring the degree of tarnishing of dental alloys.