Lessons from the past.
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003695:Delivery of Health Care / Q000639:trends; D006293:Health Promotion; D006296:Health Services; D006801:Humans; D007223:Infant; D008875:Middle Aged; D009909:Oral Health; D011315:Preventive Medicine