Past infection with hepatitis B virus in patients at a dental school

Samples of blood from 327 new patients at a dental school were tested by radioimmunoassay for the presence of hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody (anti-HBs). The data were compared to the patients' histories of hepatitis. Through a statistical analysis, it was indicated that significant numbers of patients with no history of hepatitis had been infected with hepatitis B virus.