[A study on the extraoral cervical traction in the treatment of skeletal Class II division 1 malocclusion in mixed dentition].
OBJECTIVE
To evaluate the effects of extraoral cervical traction on skeletal Class II division 1 malocclusion of early or late mixed dentition and discuss the optimal treatment timing.


METHODS
The sample consisted of two groups of skeletal Class II division 1 malocclusion. One group with 11 cases was treated started in early mixed dentition while the other with 15 cases in late mixed dentition. All cases were treated with extraoral cervical traction headgear. Cephalometric analysis was conducted to evaluate the treatment effects. Student's t test was applied for statistical analysis.


RESULTS
SNA, ANB and the length of maxilla (A-Ptm) were reduced and the inclination of maxillary incisor was decreased in both two groups. When comparing the two groups, it was found that the reduction of SNA was more notable, which means the inhibition of the maxilla was more evident in late mixed dentition. The difference was statistically significant (P<0.01). There was no significant difference on the distalization of the first upper molar between two groups (P<0.01).


CONCLUSIONS
The extraoral cervical traction might be more effective in late mixed dentition to restrain maxillary growth in the treatment of skeletal Class II division 1 malocclusion.
Sun
Yan
Y
Department of Orthodontics, Ninth People's Hospital, School of Stomatology, Shanghai Second Medical University, China. sunyan173@msn.com
Liu
Hong-hu
HH
Cao
Hui-ju
HJ
D003818:Dentition, Mixed; D005115:Extraoral Traction Appliances; D006801:Humans; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008437:Maxilla / Q000254:growth & development; D014143:Traction / Q000379:methods*