Hi hteller! M77.8 – Other enthesopathies, not elsewhere classified M77.9 – Enthesopathy, unspecified Great question. Basically, the difference lies between “unspecified” and “other specified”. Other specified is always the preferred option, when appropriate. Unspecified means either the doctor doesn”t know exactly what it is, or didn”t document it. Other specified means the doctor does know what it is/documented it, but there simply isn”t an ICD-10 code that currently exists that accurately described the diagnosis/condition. So, yes since there isn”t currently an ICD-10 code that specifically states tendonitis of the jaw, that is certain a coding option. Others to consider, depending on the patient”s condition: R68.84 – Jaw pain M26.69 – Other specified disorders of temporomandibular joint M27.2 – Inflammatory conditions of jaws M65.28 – Calcific tendinitis, other site Hope this helps!