ObjectivesTo establish the prevalence of impacted third molars in an asymptomatic population and characterize the impaction and its sub-types in this population. Material and methodsBy the analysis of orthopantomograms, and using a descriptive protocol, in witch the confidentiality of data was respected, a clinical-radiological study of individuals that have been assisted in the dental clinic of C.E.S.P.U. in Gandra, for the first time, during the year 2005 was undertaken, and data was obtained regarding the presence or absence of the third molars on the arcades. The tooth was defined as being ectopic, impacted, semi-impacted, extracted or absent. In the cases where the third molar was observed on the arcade or where an impaction or semi-impaction was detected its relative position was recorded: horizontal, vertical, mesioangular, or distoangular. ResultsWe can evidence that the ages with bigger percentages of existing individuals in the sample are: of the 16 to the 25 years. The positioning of the impacted third molars most frequent is the ones that present a normal situation of eruption with a vertical positioning. Most of the individuals does not present any complication of the inclusion. ConclusionsThe third molar ones although to be gifts in the great majority of the population, only in a small percentage if present in its all. The dental caries of the adjacent tooth is associated with the inclination and the position of the third molar ones. The relation between the third molar and inferior alveolar nerve are, in some cases, very next.