Abstract
Among 20,333 people aged 15 yr or above, the prevalences of oral white lesions were calculated based on a partly new classification. The total prevalences were: cheek and lip biting 5.1%, smoker''s palate 1.1%, frictional white lesion 5.5%, snuff dipper''s lesion 8.0%, preleukoplakia 6.4% and leukoplakia 3.6%. If all these lesions were pooled, the prevalence was 24.8% and if only the entities cheek and lip biting and smoker''s palate were excluded it became 20.1%. If weak "preleukoplakic" lesions were excluded from the latter figure the prevalence for marked whitish lesions was 13.8%. Etiologic and clinical subgroups of leukoplakia showed the following prevalences: using the etiologic subgroups, idiopathic leukoplakia 0.7% and tobacco-associated leukoplakia 2.9%; using the clinical subgroups, homogeneous leukoplakia 3.5% and non-homogeneous leukoplakia 0.3%. The intraoral location pattern of leukoplakias was preponderant in the commissural and buccal areas. However, the idiopathic leukoplakias showed a somewhat more even distribution and thus a more similar distribution to that of oral cancer.