摘要
agenesis is the absence of teeth by genetic alterations, single or as syndrome. agenesis of third molar is associated to malformations and is considered by diverse authors a consequence of the human evolution (larmour et al., 2005). the third molars together with second premolars and lateral incisors are the teeth with greater prevalence of agenesis (fuller %26 denehy, 1984). the prevalence var赤es between 9% and 37% (mcnamara %26 foley, 2006); arboleda et al. (2006) indicated a prevalence of 20%. literature indicate variable percentage, by gender, dental arches, side and tooth, with few arricies on original groups of chile. the population in study consisted of 33 men and 57 women between 16 and 55 years of the ethnic group of at芍camenos, without extractions of third molar ˋor orthodontic treatments and without congenital malformations. hybridism was determined by means of serum technique by blood agglutination and by application of the formula of bernstein, demonstrated a 56% of indigenous mixture. to each individual a panoramic x-ray was taken to observe presence or absence of third molars. a 26.7% of individu芍is with agenesis of one or more third molars was determined, with greater percentage among males. agenesis lower third molar predominates in the sample and in men; however in women are greater agenesis upper third molar. in addition, agenesis predominates of the left side in both sexes, while in men equal bilateral percentage is verified. agenesis of two molars predominates in both sexes. statistical analyses did not show significant differences at the 95% level, and the results, in general, agree with those in the literature. this research represents a contribution to the anthropology of the north of chile, but it is not possible to determine ethnic variables considering the small sample in study.