Every person in every photo is white.
Note to dentists: Even in Sandy, Utah, not everyone is caucasian. Not even if you weed out the toothless.
I suppose one could argue that the dentist's objective is not to promote racial equality, but to acquire new patients. Moreover, 89% of Utah is white, so one could argue that the dentist is appealing to the greater market.
From a pure marketing view, I can't argue against those points. But I can as a marketer who also happens to be a human being. Advertising has a powerful opportunity to depict the human family as more than one ethnicity, without (except in rare cases) compromising other objectives. Given the human tendency to separate into "us" and "them," it's an opportunity we shouldn't waste.
I doubt that the dentist intended any slight. This is the kind of oversight that's easy to make. Which is exactly why we all need an occasional reminder. I hope this one serves.