The second most frequent type of article (n -- 30) was the case report, a category of publication that described the influence of certain orthodontic treatment modalities used in one or more patients on the signs
and symptoms of temporomandibular dysfunction. The least numerous (n = 6) were in the third category,
that of sample studies, investigations that reported data from large sample groups. These studies were of
variable quality, often having the same methodologic problems and limitations as discussed previously for
studies of occlusal factors. Since 1988, however, a substantial number of clinical investigations have
considered the association of orthodontics and TMDs.