title: The natural history of periodontal disease in man. Changes in gingival health and oral hygiene before 40 years of age.
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D003773:Dental Plaque / Q000453:epidemiology / Q000209:etiology; D005260:Female; D005891:Gingivitis / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D008297:Male; D009664:Norway; D009909:Oral Health; D009910:Oral Hygiene; D010510:Periodontal Diseases / Q000453:epidemiology* / Q000209:etiology; D010512:Periodontal Index; D013188:Sri Lanka