I don't have an ear infection or tooth infection, what could cause ear fullness?

TMJ disorder. Temporo-mandibular disorder is the second most frequent cause of orofacial pain after dental pain. Earache, ear fullness are the common symptom due to the close location to TMJ. Proper diagnosis is the key to the successful treatment. See orofacial pain practitioner for a consultation and treatment.
TMJ. A TMJ disorder can cause the lower jaw bone to be pushed up too close to the eustacian tube, which can cause the feeling of fullness. See an ENT to rule out an ear problem first.
TMJ. If you do not have any problems hearing with your ear fullness, it may be related to your temporomandibular joint, that is the joint where your jaw joins your skull. This area can get inflamed from grinding your teeth or from an altered bite from dental work. Because of its close proximity to your ear, the pressure from the joint's inflammation can cause the sensation of fullness.