The effects of modified maxillary protraction on the soft tissue profile of patients with maxillary hypoplasia during the later period of pubertal peak
Objective:To study the effects of modified maxillary protraction therapy on the changes in facial soft tissue in patients with maxillary hypoplasia using cephalometric measurements.Methods:26 cases(16 males and 10 females)of Class Ⅲ skeletal malocclu-sion with maxillary hypoplasia during the later period of pubertal peak(CVM Ⅴ to Ⅵ)were included.Treatment was carried out using modified palatal anchorage with a combination of a modified bite-jumping appliance and bilateral maxillary anterior traction.Cephalo-metric measurements were taken before and after treatment using lateral cephalograms,the changes in facial soft tissue-related parame-ters were compared.Results:(1)After treatment,the measurements of soft tissue landmarks in the midfacial region showed a signifi-cant increase(P＜0.05),with the average anterior movement exceeding 3 mm for the nasal tip,subnasale,soft tissue A point and upper lip protrusion point.(2)The changes in the G-Sn-Pos,Ns-Prn-Pos,and S-Ns-Sn were highly significant(P＜0.01),with an average increase in the G-Sn-Pos of 3.23°±3.74°,a decrease in Ns-Prn-Pos of 2.56°±4.99°,and an average increase in S-Ns-Sn of 2.63° ±3.39°.(3)Changes in soft tissue tension and facial height proportion after treatment were not statistically significant(P＞0.05).Con-clusion:The use of a modified pad type intraoral appliance in conjunction with bilateral maxillary anterior traction can effectively pro-mote the improvement of mid facial soft tissue profile in patients with maxillary underdevelopment during the peak growth and develop-ment period,and coordinate the relationship between nasal,lip and chin soft tissue.
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