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A randomized clinical trial of two alternative designs of Twin-block appliance
Michael John Trenouth1, Stephen Desmond
1Royal Preston Hospital Preston, Lancashire, UK. karen.pool@lthtr.nhs.uk
Objective:
To test if placing a Southend clasp on the upper and lower incisors during Twin-block appliance treatment will control their angulation and enhance skeletal correction.
Design:
Prospective, randomized, controlled clinical trial (ISRTCTN 45965219).
Setting:
Orthodontic Department, Royal Preston District General Hospital, Preston, UK.
Participants:
Fifty-two consecutive patients aged 9-30 years undergoing treatment for Class II division 1 malocclusion (ANB>5°, OJ>6 mm).
Methods:
Two alternative designs of Twin-block appliance were allocated randomly. One with a Southend clasp on the upper and lower central incisors and one without. The appliances were identical in all other aspects.
Outcomes:
Skeletal and dental changes measured on before and after treatment lateral cephalometric radiographs.
Results:
There was a statistically significant change in ANB angle between the Southend group (-3·5°) and the Non-Southend group (-2·6°) (P = 0·004). The change in upper incisor angulation was -6·1° for the Southend group and -12·0° for the Non-Southend group, which was statistically significant (P = 0·005). The change in lower incisor angulation was 3·0° for the Southend group and 6·9° for the Non-Southend group, which was statistically significant (P = 0·005).
Conclusions:
The presence of a Southend clasp on the upper and lower incisors during Twin-block treatment limited their tipping which enhanced the skeletal correction.
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