Hi Guest!

what we have found is that the two codes that are currently most commonly accepted by medical insurers for TMJ disorder appliances are:
D7880 - occlusal orthotic device, by report
21299 - Unlisted craniofacial and maxillofacial procedure

Of course, a narrative report explaining the treatment accompanying the claim is recommended since they are "by report" and “unlisted” codes 😊
(I always suggest to use the ZZ qualifier on the line item in the supplemental information area (which is the red shaded line on each line item in field 24 that is typically left blank) and providing a short description there since they are unlisted & by report codes).

You will also need the diagnosis code(s) for TMJ disorders - options are as follows:

M26.611 - Adhesions and ankylosis of right temporomandibular joint
M26.612 - Adhesions and ankylosis of left temporomandibular joint
M26.613 - Adhesions and ankylosis of bilateral temporomandibular joint

M26.621 - Arthralgia of right temporomandibular joint
M26.622 - Arthralgia of left temporomandibular joint
M26.623 - Arthralgia of bilateral temporomandibular joint

M26.631 - Articular disc disorder of right temporomandibular joint
M26.632 - Articular disc disorder of left temporomandibular joint
M26.633 - Articular disc disorder of bilateral temporomandibular joint

M26.641 Arthritis of right temporomandibular joint
M26.642 Arthritis of left temporomandibular joint
M26.643 Arthritis of bilateral temporomandibular joint

M26.651 Arthropathy of right temporomandibular joint
M26.652 Arthropathy of left temporomandibular joint
M26.653 Arthropathy of bilateral temporomandibular joint

M26.69 - Other specified disorders of temporomandibular joint


You may also consider secondary/symptom diagnosis codes, suck as G50.1 (atypical facial pain) or M79.11 (Myalgia of mastication muscle)

Hope this helps!