Incisor position objective for favorable profile in orthodontic camouflage treatment of skeletal class II cases.

Background: This study aimed to screen favorable and unfavorable profile outcomes in orthodontic camouflage treatment of skeletal Class II cases, based on which to identify the reference line and the associated value for the optimal incisor position objective (IPO) in such cases.

Methods: A total of 140 Chinese adult skeletal Class II cases were included, who finished orthodontic camouflage treatment with anterior retraction following premolars extraction. Post-treatment lateral cephalograms were trimmed and converted into silhouettes, rated by a panel of orthodontists. The top 30% and bottom 30% ranked cases were included as the favorable and unfavorable profile group respectively. The distances of U1 anterior to the GALL line (U1-GALL), point A vertical (U1-Av), and ANS-Pog line (U1-ANPo) were measured as IPO indicators.

Results: U1-ANPo in the favorable profile group was 4.74 ± 1.65 mm, significantly different from that in the unfavorable profile group (6.02 ± 3.61 mm). U1-GALL was -2.68 ± 2.30 mm and -1.12 ± 2.02 mm, and U1-Av was 4.49 ± 3.97 mm and 6.22 ± 4.42 mm, in the favorable and unfavorable profile group respectively, neither showing significant difference. Among three indicators, only U1-ANPo had a significant discriminatory capacity (AUC = 0.74, P = 0.007) for differentiating between the favorable and unfavorable profile group.

Conclusions: In skeletal Class II orthodontic camouflage treatment, the relatively favorable post-treatment profiles are associated with the U1 position anterior to the ANS-Pog line. U1-ANPo of around 4.7 mm could be tentatively proposed as a practical IPO reference in treatment planning for such cases.