1. 1.D Locker . Aging of a Modern Population. Aging and Oral Health. An Introduction to Behavioural Science and Dentistry , 1st edn. Tavistock: Routledge, 1989 : 59 -72 .
2. 3.National Centre for Health Statistics.,Health,United States,1986 and Prevention Profile, 1986 : 13 -14 .