Ectodermal dysplasias are a large group of syndromes characterized by anomalies in the structures of ectodermal origin. There are 2 major types of this disorder, based on clinical findings: hypohidrotic ectodermal dysplasia and hidrotic ectodermal dysplasia. This clinical classification is very important because clinical professionals involved with this disease need first a clear and practical method of diagnosis. The main oral manifestation of ectodermal dysplasia may be expressed as hypodontia. Thus, dental professionals may be the first to diagnose ectodermal dysplasia. The present article reports one case of each of the main types (hypohidrotic and hidrotic) of ectodermal dysplasia and the authors review the literature regarding the pathogenesis, clinical features, and therapeutic management of this condition.