Functional Shift of the Mandible Clinical Trial
Official title:
Is the Quad Helix More Efficient to Correct Mandibular Asymmetry Before Age 7? A Retrospective Comparative Study
To compare the effectiveness of the Quad Helix, an orthopaedic conventional appliance, in the correction of skeletal mandibular asymmetry, on frontal x-ray, in subjects treated before or after 7 years.
Introduction : Unilateral posterior crossbite (UPCB), often from dysfunctional and
para-functional causes, leads to positional mandibular asymmetries that can develop at a very
young age into skeletal mandibular deviation; hence the interest of early maxillary
expansion. The purpose of this retrospective study was to compare the impact of maxillary
expansion by Quad Helix (QH) on mandibular skeletal asymmetry correction before and after 7
years of age.
Materials and methods : All children with UPCB and skeletal mandibular asymmetry, who were
treated by QH in the orthodontic department between February 2017 and August 2018 and who
have done a radiography file at baseline (T0) and 12 months later (T1) have been included.
The patients were divided into two groups according to age: under 7 years of age (early group
G1) with QH adjusted on second primary molars and over up to 13 years old (late group G2)
with QH adjusted on first permanent molars. The differences between the right and left sides
of the mandible in corpus length L (main eligibility criterion) and ramus height H (secondary
criterion) were compared between groups. X² test, Fisher's exact test and Wilcoxon rank-sum
tests were used for baseline comparisons. A multifactorial analysis allowing adjustment on
possible confounding factors was used with R software at a significance level of 5%.
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