Lower incisor inclination changes during Xbow treatment according to vertical facial type

To evaluate the magnitude of lower incisor inclination associated with the vertical facial type in adolescent Class II patients treated with the Xbow appliance.

A total of 172 consecutive Class II patients treated with only the Xbow appliance were used. The sample was divided into three groups based on their vertical facial type (24 short, 122 normal, and 25 long facial types). The mean age was 11.11 years at T1 with a mean active Xbow time of 4.5 months. A mean of 6.4 months passed after the Xbow deactivation before T2 radiograph.

No significant association between lower incisor proclination and vertical facial type was found. Actual differences between T1 and T2 did exist. In most cases, these differences may be considered clinically relevant, but when the large interindividual variability is considered, the differences between the groups could not be statistically supported. At T1, a distinct trend to have more proclined lower incisors in the short (100.5 degrees ) compared with the long (91.3 degrees ) facial types was found. During treatment, a trend was identified for more proclination of the lower incisor the shorter the face.

Although lower incisors do procline with the use of the Xbow appliance, facial type does not appear to affect the amount of lower incisor inclination. The magnitude of the incisor proclination can be considered not clinically relevant, but a large individual variation in the incisor response was identified.