330 cases of impacted mandibular third molar were divided into 3 groups,A:younger than 18 years,B:18-25-year-old,C:ol-der than 25-year.Operation time(min)of group A,B and C was 21.95 ±5.86,6.45 ±4.92 and 18.77 ±9.64(B vs A or C,P <0.01), intraoperative complication rates were 2.73%,6.36% and 30.91%(P <0.01),postoperative complication rates were 51.82%,23.64%and 66.36%(P <0.05),respectively.18-25 year-old is the suitable age for removal of impacted mandibular third molars.

To study the therapeutic effect of the combination of orthodontics and fixed denture renovation preliminary in treating consecutive teeth loss. Before the fixing denture renovation,12 cases of consecutive teeth loss were treated to become interval teeth loss by using the orthodontic treatment. All patients received simultaneous functional and cosmetic restoration. The abutment teeth were healthy and the renovational teeth were stable. The combination of orthodontics and fixed denture renovation showed good effect in treating the consecutive teeth loss. It is a good clinical renovation. It is worthy to apply in clinic.