1Silness J. Periodontal diseases in pregnancy. Ⅱ .correlation between oral hygiene and periodontal condition [J]. Acta Odanto Scand, 1984, 24:7 47.
2Loe H.The gingival index, the plaque index and rention index system [J]. J Periondtol, 1987, 38:610.
3Atack NE, Sandy JR, Addy M. Periodontal and microbiological changes associated with the placement of orthodontic appliances: A review[J]. J Periodontal, 1996,67 (2) :78-85.
3Davies TM, Shaw WC, Worthington HV, et al, The effect of orthodontic treatment on plaque and gingivitis[J]. Am J Orthod Dentofac Orthop, 1991,99:155.
4Siegward D. Effeetives of three different types of electric toothbrushes compared with a manual technique in orthodontic patients[J]. Am J Orthod Dentofac Orthop, 1996,110:630.
