| Summary: | 碩士 === 高雄醫學大學 === 牙醫學研究所 === 99 === Introduction: The aim of this retrospective study was to compare the effects of various anchorage setups, and also compare the treatment outcomes of orthodontic treatment and anterior segmental osteotomy for correction of bimaxillary protrusion. The difference of pre-treatment cephalomatric characteristics was also investigated.
Methods: The sample consisted of 75 non-growing patients with Angle Class I bimaxillary protrusion who received extraction treatment and were divide into 5 groups. Group 1 (n=19) received traditional anchorage preparation without headgear ; Group 2 (n=10) received traditional anchorage preparation with high pull headgear; Group 3 (n=19) received upper bilateral posterior skeletal anchorage; Group 4 (n=9) received upper and lower bilateral posterior skeletal anchorage; Group 5 (n=18) received upper and lower modified anterior segmental osteotomy(ASO) plus genioplasty. Pretreatment and posttreatment lateral cephalograms were superimposed. One-way ANOVA and Tukey HSD tests were utilized to compare the pretreatment morphological characteristics and treatment changes among the 5 groups. ANCOVA was used to compare the treatment changes among the 5 groups after pre-treatment value adjusted.
Results:
Comparison of cephalometric variables before treatment
1. Before treatment, the incisors were protrued and proclined among the 5 groups, but in group 5, the incisors showed more uprighted than in the other groups.
Comparison of treatment changes in cephalometric variables
1.After treatment, group 5 showed largest advancement of the retrued chin among the 5 groups.
2.The improvement of skeletal horizontal discrepancy was greatest in group 5.
3.Group 5 showed a decreased upper nasolabial angle.
4.The change in facial divergence had no significant difference among group 1, 2, 3, and 4.
5.Group 2, 3 and 4 had maximal retraction of upper incisors, and there was no significant difference among group 2, 3, and 4.
6.There was greater retraction of upper incisors in group 4 than in group 1, but after pre-treatment value adjusted, the result presented no significant difference.
7.The improvement of anterior teeth proclination was greater in group 3 and group 4 than in group 5.
8.The treatment duration of group 2 was longer than group1, 3, 4, and 5.
Conclusions:
1.The group treated with modified Wunderer’s technique of anterior segmental osteotomy presented more uprighted incisors before treatment.
2.Anterior segmental osteotomy combined with genioplasty apparently improved retrued chin and skeletal horizontal discrepancy.
3.The modified technique may decrease the upper nasolabial angle but further investigations were needed to prove it.
4.There was no significant different change in the facial divergence between skeletal anchorage groups and traditional anchorage groups.
5.Anterior teeth had maximal retraction both in the group with skeletal anchorage and with high pull headgear, but treatment duration was longer in the group with high-pull headgear.
6.When using skeletal anchorage for anterior teeth retraction, we must control anterior torque carefully.
7.The retraction of upper and lower lips was not significant different among the skeletal anchorage groups and the traditional anchorage groups. Lip structure seemed to have an influence on lip response to incisor retraction and it is necessary to find the reason in future studies.
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