The investigation of third molar eruption space after treatment of non-extraction or premolar extraction

Objective:To discuss the feasibility of reservation 28 teeth through investigation of third molar eruption spaces after treatment of non-extraction or premolar extraction.Method:Samples were from orthodontic department of Shenzhen Children's Hospital,132 males and 165 females,of which 201 youth group,96 adult group.All samples were treated with non-extraction or premolar extraction.The post-treatment panoramic radiographs were analyzed.The eruption spaces and crown width of third molars were measured.Result:The absent eruption spaces of third molars showed that non-extraction group was larger than premolar extraction group,maxillary jaw was larger than lower jaw,youth group was larger than adult group.The difference was significant;In the adult group,70 % of patients could be treated by non-extraction or molar extraction to obtain the purpose of reservation 28 teeth.Conclusion:Premolar extraction can not statistically solve third molar eruption spaces.Design of molar extraction was feasible for most orthodontic patients to obtain the purpose of reservation 28 teeth.It is a great probability event,scientific and rational.