Hi Guest!
Yes we do not recommend using 21110 or 21089 for appliances used to treat TMD, as these codes do fall into the surgical category of CPT coding.
21110 stands for: Application of interdental fixation device for conditions other than fracture or dislocation, include removal
21089 stands for: Unlisted maxillofacial prosthetic procedure
Although we have had several report of insurers telling practices to use one of the codes listed above as what happened in your case. The request for additional documentation you listed in your post does seem to be geared toward a surgical service. If 21089 is in fact the code that your insurer requires an office to bill for a TMD appliance, the office should be able to send along their clinical documentation which will describe the exact procedures/services rendered.
What we are finding is that the code that is most commonly accepted by medical insurers currently for TMD appliances since the S8262 discontinuation June 2015 is D7880. However, some insurers are accepting the other codes listed below as well:
D7880 - occlusal orthotic device, by report
D7899 - unspecified TMD therapy, by report
Or, if the medical insurer says they won’t process the “D” codes (most will these days, but you will run into a few that won’t), you can try:
E1399 - Durable medical equipment, miscellaneous
21299 - Unlisted craniofacial and maxillofacial procedure
21499 - Unlisted musculoskeletal procedure, head
A narrative report explaining the treatment accompanying the claim is recommended since they are all "by report", “unlisted”, or "miscellaneous" codes.
For example, Aetna's medical policy for Temporomandibular disorders lists D7880 as an accepted HCPCS code is criteria is met:
http://www.aetna.com/cpb/medical/data/1_99/0028.html If you would like to tell me the name of your insurance company, I would be happy to locate the medical policy online if it is available and see if there is a specific code listed in their policy like Aetna's.
Hope this helps!