Root canal charge - unspecified procedure #3999

I had a route canal. When I got the bill there was a $95 charge for an "unspecified procedure".  Aetna covered most of the root canal but denied this charge (and I have to pay it as well as some others that they didn't fully cover).  They say "This service was denied because the dental office submitted a procedure not recognized by the American Dental Association.  It is then designated an unspecified procedure code and denied.  With a corrected
ADA code, or an explanation of services, we can reconsider the service for payment."

I then called the Doc and they tell me that they used code 3999 (ADA code) since it was for deep roots and they they included an explanation but sometimes the insurance company won't cover it.  (They have not yet received the claim/payment back yet but charged me what they thought my part would and now owe me nearly 40% of my payment back too.)

I am confused as what they tell me doesn't match what the insurance company tells me.  I tried to look up a code 3999 and don't see anything specific.  Something sounds suspicous.

Thoughts?

[desmo907]

Seems Aetna doesn't cover some procedures, so they say (they  call them exclusions but don't list them anywhere). Case closed! Grrr