Google has dumped all 3rd party reviews that it used to be syndicating to their Places pages.
Many dental practices that were taking the "easy route" using DemandForce, Yelp, Droogle, and others have now been left out in the cold with little (or no) patient testimonials to show for their money and efforts.
One thing is for sure - with Google's recent management change-up, we can expect many more BIG changes to come. We've already seen Panda and what it's done to the rankings of many dental websites, I think this is only the tip of the iceberg for Google solidifying and consolidating their brand.
I posted a video on this back in December of 2010, this has been a long time coming... take a look at it and learn how to Save Your Google Places page: