the occlusal interferences are a frequent problem in temporal and mixed dentition. they are associated to functional malocclusions with anterior crossed biting, posterior crossed biting, and also to facial anomalies and affections of the temporomandibular articulation. we carried out a descriptive, observational, transversal study, where we examined 820 primary school children of the contreras health area, municipality of matanzas, to identify the occlusal interferences related to the presence of functional anterior crossed biting, functional unilateral posterior crossed biting. 138 of the examined children presented occlusal interferences; 36.9 % of them presented anterior crossed biting, and 63.0 % posterior crossed biting. the precocious detection of occlusal interferences will give us the possibility of intercepting dental malocclusions and also of preventing dentomaxillofacial anomalies and alterations of the temporomandibular articulation.