[Soft tissue linear evaluation of fixed Twin-block appliance treatment and tooth extraction in skeletal Class II malocclusion].
OBJECTIVE
This cephalometric study was designed to evaluate the soft tissue profile effects of Twin-block combined with straight wire appliances to treat growing adolescents with skeletal Class II malocclusion and mandibular retrognathia.


METHODS
The samples comprised 31 growing individuals with skeletal Class II and mandibular retrognathia. They were divided into 2 groups. The study group (18 patients) was treated with fixed Twin-block combined with fixed appliance, while the control group (13 patients) was only treated with fixed appliance after tooth extraction. Pretreatment and posttreatment lateral cephalograms were taken before and after Twin-block treatment and after all the fixed appliance treatment. Linear cephalometric measurements of soft tissue were analyzed statistically. Intragroup and intergroup changes of the 2 groups were evaluated using SPSS 15.0 software package.


RESULTS
Significant changes of G'-Pg', Li-1, Si-B and Ls-E line between before and after treatment were found in the study group, while Li-1, Ls-E line and Li-E line changed significantly in control group. The change of Li-E line was different between the 2 groups.


CONCLUSIONS
Twin-block combined with fixed appliance treatment is better than extraction with fixed appliance treatment in promoting lower facial profile in cases of skeletal Class II malocclusion and mandibular retrognathia with growth potentials.
Department of Orthodontics,Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; Shanghai Key Laboratory of Stomatology. Shanghai 200011, China.E-mail:gongyao0328@hotmail.com.
Yao
Y
Gong
Pei-lun
PL
Li
Hong-hong
HH
Wang
Quan
Q
Yu
Bin
B
Wei
Gang
G
Shen
D000293:Adolescent; D002508:Cephalometry; D006801:Humans; D008312:Malocclusion, Angle Class II; D008334:Mandible; D017289:Orthodontic Appliances, Functional; D009969:Orthodontic Wires; D063173:Retrognathia; D014081:Tooth Extraction