3Hattab FN.Positional changes and eruption of impacted mandibular third molars in young adults:A radiographic 4-year follow -up study[J].Oral Surg Oral Med Oral Pathol Oral Radiol Endod,1997,84:604 -612
4Richardson ME.The role of the third molar in the course of late lower arch crowding.A review[J].Am J Orthod.Dentofacial Orthop,1989,95-79
5Lindquist B.Thilander B.Extraction of third molars in cases of auticipated crowding in the lower jaw[J].Am J orthod,1982
6Hunt EE.Malocclusion and civilization[J].Am J Orthid,1961,47:406 -22
7Odusanya SA,Abayomi IO.Third molar eruption among rural Nigerians[J].Oral Srug Oral Med Oral Pathol,1991,71:151 -4