Aims: To test the hypothesis that oral parafunctions and symptomatic temporomandibulair joint (TMJ) hypermobility are risk factors in adolescents for both anterior disc displacement with reduction (ADDR) and intermittent locking. Methods: Participants were two hundred sixty 12- to 16-year-old adolescents (52.3% female) visiting a university clinic for regular dental care. ADDR and symptomatic TMJ hypermobility were diagnosed using a structured clinical examination. During the anamnesis, reports of intermittent locking and of several parafunctions were noted, eg, nocturnal tooth grinding, diurnal jaw clenching, gum chewing, nail biting, lip and/or cheek biting, and biting on objects. The adolescents' dentitions were examined for opposing matching tooth-wear facets as signs of tooth grinding. Risk factors for ADDR and intermittent locking were first assessed using univariate logistic regression and then entered into a stepwise backward multiple model. Results: While in the multiple model, ADDR was weakly associated only with increasing age (P = .02, explained variance 8.1%), intermittent locking was weakly correlated to diurnal jaw clenching (P = .05, explained variance 27.3%). Conclusion: In adolescence, diurnal clenching may be a risk factor for intermittent locking while age may be a risk factor for ADDR. Symptomatic TMJ hypermobility seems to be unrelated to either ADDR or to intermittent locking. Keywords: anterior disc displacement, human, internal derangement, oral parafunctions, symptomatic TMJ hypermobility, temporomandibular joint