Ah, the arrival of a new Vita 3-D Master Shade Guide...
Two of them, actually.
The thing about shade guides is, they do degrade over time. The color references are not quite calibrated precisely after some years of use, and this has a negative effect on our ability to match shades of dental restorations. We'll still use the old ones for general what-shade-are-my-teeth purposes at recall visits, but when matching shades for crowns and other restorations, the new ones are essential to achieving ideal matches.
More on the subject of tooth shades:
Oh, and those three very light shades on the left?
Vita had to add them on. Because of the weatherpeople on TV.
You know, weatherpeople. They generally have the whitest veneers of anyone in show business, which is a business laden--overburdened even--with white teeth. I'm not sure quite why, since A-list movie actors and such make much more income, but weatherpeople have generally gone to American Standard Toilet Bowl White as the ombre de choix for their teeth, outshining those A-listers by a wide margin.
Those left three shades are not, by the way, attainable by whitening methods. They are only attainable by dental porcelains, as in veneers and crowns.
Weatherperson American Standard White, that's what I call the lightest one.