among the researches undertaken in epidemiology, a peculiar group of pathologies present either unknown or not totally understood origins. temporomandibular disorders (tmd) can be classified in this subgroup. three basic observational strategies have been used to approach the etiologic role of malocclusion in tmd development, inside the epidemiological repertoire. they are sectional, case-control and cohort studies. some clinical trials are conducted based on the removal of the suspect etiologic factor. based on the literature reviewed in terms of the methodology applied in the selected studies, we can infer that: the definition of possible etiological factors related to specific sub-groups of tmd is primordial not to underestimate the role of malocclusion in the development of this kind of disorders; the characterization of a normal occlusion like the one associated with the lower risk for tmd problems development can be useful, but the application of these parameters will probably result inappropriate for the resolution of a joint problem which is already established; the concept of lower risk occlusion would involve a small slide discrepancy between rcp and icp, small incisal overlap, positive overbite and no posterior crossbite. this concept is similar to the concept of normal occlusion supported for decades, although a deviation from the normal criterion instead of an absolute criterion must be tolerated; although it may be prudent to establish therapeutic morphologic goals that seek what is observed in untreated occlusions deemed normal or ideal, the establishment of an occlusion that reach all these gnathologic criteria, by means of orthodontic treatment, might be either impossible or probably unnecessary.