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Effects of maxillary protraction therapy on facial soft tissue in patients with skeletal class III malocclusion

Yandong Xiao, Wei Liu, Ping Sun, Ce Xin, Yanxiao Du, Bo Ding

Objective: To explore the effects of maxillary protraction therapy on facial soft tissue in patients with skeletal class III malocclusion (Occ).

Methods: From May 2016 to March 2017, 25 patients with skeletal class III malocclusion enrolled in our hospital were chosen as the study objects. All patients were treated with rapid maxillary expansion and protraction, and changes of their facial soft tissue profile were measured and analysed before and after therapy.

Results: After treatment, distance from the nasal apex to the Y axis (Y-Prn), upper lip angle (S-Ns-Sn), the upper lip protrusion distance (UL-E), convex upper lip thickness (UL-U1), distance from upper lip concave point to Y axis (Y-As), distance from labrale superius to Y axis (Y-UL) and chin angle (LL-Bs- Pos), thickness of symphysis (Pos-Po), soft tissue under the high (Sn-Mes) and H angle were all increased. And these data contrasts were significant before and after the treatment (P<0.05). After treatment, soft tissue facial angle (FH-Ns Pos), lower lip base angle (S-Ns-Bs), and the distance from soft tissue pogonion to the Y axis (Y-Pos) were decreased. And these data contrasts were significant before and after the treatment (P<0.05).

Conclusion: Maxillary protraction therapy can improve the facial soft tissue of patients, move up the upper lip and improve mentolabial relationship.