Occurrence of leukoplakia and some other oral white lesions among 20,333 adult Swedish people.

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.