[Oral lichen planus: epidemiological observations in Argentina].

: The prevalence of the oral lichen planus and its distribution by sex, age and clinical forms was studied in population's samples and series of cases. The prevalence rates observed ranged from 0.129 to 0.38% with the highest values (0.66%) in the oldests groups of age. In the series of cases no significant differences were observed in sex distributions with increased values of prevalence, in both sexes, over 40 years of age and the highest values in the fifth decade of life. Atypical clinical forms, specially erosive forms, predominated in the series of cases but not in the population samples. Their true occurrence must be establish by epidemiological works on wider samples of people.