3Alkhatib MN,Holt R,Bedi R.Prevalence of self-assessed tooth discelouration in the United Kingdom[J].J Dent,2004,32(7):561-566.
4Whelton HP,Ketley CE,McSweeney F,et al.A review of fluorosis in the European Union:Prevalence,risk factors and aesthetic issues[J].Community Dent Oral Epidemiol,2004,32(Suppl 1):9-18.