Early treatment for Class II Division 1 malocclusion with the Twin-block appliance: a multi-center, randomized, controlled trial.
BACKGROUND
The aim of this study was to evaluate the effectiveness of early orthodontic treatment with the Twin-block appliance for the treatment of Class II Division 1 malocclusion. This was a multi-center, randomized, controlled trial with subjects from 14 orthodontic clinics in the United Kingdom.


METHODS
The study included 174 children aged 8 to 10 years with Class II Division 1 malocclusion; they were randomly allocated to receive treatment with a Twin-block appliance or to an initially untreated control group. The subjects were then followed until all orthodontic treatment was completed. Final skeletal pattern, number of attendances, duration of orthodontic treatment, extraction rate, cost of treatment, and the child's self-concept were considered.


RESULTS
At the end of the 10-year study, 141 patients either completed treatment or accepted their occlusion. Data analysis showed that there was no differences between those who received early Twin-block treatment and those who had 1 course of treatment in adolescence with respect to skeletal pattern, extraction rate, and self-esteem. Those who had early treatment had more attendances, received treatment for longer times, and incurred more costs than the adolescent treatment group. They also had significantly poorer final dental occlusion.


CONCLUSIONS
Twin-block treatment when a child is 8 to 9 years old has no advantages over treatment started at an average age of 12.4 years. However, the cost of early treatment to the patient in terms of attendances and length of appliance wear is increased.
O'Brien
Kevin
K
School of Dentistry, University of Manchester, Manchester, United Kingdom. Kevin.O'Brien@manchester.ac.uk
Wright
Jean
J
Conboy
Frances
F
Appelbe
Priscilla
P
Davies
Linda
L
Connolly
Ivan
I
Mitchell
Laura
L
Littlewood
Simon
S
Mandall
Nicola
N
Lewis
David
D
Sandler
Jonathan
J
Hammond
Mark
M
Chadwick
Stephen
S
O'Neill
Julian
J
McDade
Catherine
C
Oskouei
Mojtaba
M
Thiruvenkatachari
Badri
B
Read
Michael
M
Robinson
Stephen
S
Birnie
David
D
Murray
Alison
A
Shaw
Iain
I
Harradine
Nigel
N
Worthington
Helen
H
D000293:Adolescent; D000367:Age Factors; D002508:Cephalometry; D002648:Child; D003362:Cost-Benefit Analysis; D003818:Dentition, Mixed; D005260:Female; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D017289:Orthodontic Appliances, Functional; D009972:Orthodontics, Interceptive / Q000191:economics / Q000295:instrumentation*; D012649:Self Concept; D016896:Treatment Outcome; D006113:United Kingdom