There are groups that will negotiate fees and help you navigate the affiliation connections between them all. Groups like UnlockThePPO and FiveLakes. However, to my knowledge they don't actually look at the dental contract for you, just fees.
As far as I know, there is no specific group that will help navigate the contract itself other than a contract lawyer. This is why it is so important to learn it yourself. I have read dozens of contracts by now from other dentists (I have not signed a new one in 8 years). They are boring, but not really that difficult to read or understand in most sections.