Dentofacial and upper airway characteristics of mild and severe class II division 1 subjects

The aim of this retrospective, cross-sectional study was to assess whether mild and severe Class II division 1 subjects have craniofacial and upper airway characteristics, which relate to the severity of Class II as judged by overjet or ANB angle. The sample consisted of pre-treatment lateral cephalograms and dental casts of 131 males and 115 females (mean age 10.4 +/- 1.6). Inclusion criteria were: healthy Caucasian subjects, at least 3/4 Class II first molar relationship on both sides and overjet >= 4 mm. The cephalograms were traced and digitized. Distances and angular values were computed. Mild and severe Class II was defined by overjet (<10 mm/>= 10 mm) or by ANB angle (<7 degrees/>= 7 degrees). Statistics were performed with two-sample t-test and Pearson's correlation analysis. In the two overjet groups, significant differences were mainly found for incisor inclination while the two ANB groups differed significantly in SNA, WITS, Go-Pg, SpaSpp/MGo, SN/MGo, and Ar-Gn. The shortest airway distance between the soft palate and the posterior pharyngeal wall was significantly correlated to the NS/Ar angle. Statistical analysis revealed several significant correlations. Patients with a large overjet or ANB angle differed significantly from patients with a small overjet or ANB angle mainly in their incisor inclination. In the present sample, the overjet and to some extent also the ANB angle is determined by soft tissue or individual tooth position rather than by skeletal background. In retrognathic patients, a tendency towards smaller airway dimensions was found. However, statistical analysis did not reveal a strong connection between upper airway and dentoskeletal parameters, but a large interindividual variation.