Background Degenerative changes in the temporomandibular joint might be associated with ageing and/or with the loss of occlusal support. Objective The aim of the study was to evaluate whether the inclination of the posterior slope of the articular eminence changes in association with: (i) ageing in patients with maintained occlusal support zones (OSZs); and (ii) the loss of OSZs in elders. Methods In this retrospective radiological study, selected orthopantomograms were allocated into the following groups: I—age 18–35, maintained OSZs, II—age 36–60, maintained OSZs, III—age >60, at least one OSZ per side maintained, IV—age >60, loss of all OSZs. The inclination of the articular eminence was measured relative to the Frankfort plane. Results The mean values of the inclination of the slope of the articular eminence amounted 34.05° ± 5.17°, 36.68° ± 5.65°, 34.86° ± 6.26° and 26.31° ± 5.12° for group I, II, III and IV respectively. There were no significant differences between the groups I to III. Group IV differed significantly from each of the previous groups. Conclusions Flattening of the articular eminence is associated with the loss of OSZs rather than ageing.