One of the reasons why dental practices don't get their desired result is that they don't understand that getting your content promoted through Facebook is just like getting it promoted in a magazine, or on a billboard, or on the radio.
You can create the great graphics or great words to use in a radio ad, but if you don't pay for airtime or pay for the ad to go to print, it stays on someone's desk.
That being said, there are some cool things you can do to significantly increase reach and make posts go viral, including how you do your Facebook lives.
The docs that go through my FB course typically spend less than $500 a month and many are getting over 100 new patients a month. Their results are based on how they write the ads and how they boost them.