ObjectiveTo analyze the asymmetry of posterior-anterior radiograph of patients with facial asymmetry after orthodontic and surgical treatment. MethodsWe retrospectively analyzed the clinical data of 50 patients with varying degrees of facial asymmetry treated with orthodontic and surgical methods between June 2013 and June 2014. The asymmetric rate of posterior-anterior radiograph of the patients before and after treatment were compared with that of another 50 healthy subjects. ResultsMaxillary indexes including L2, L3, L4, L5, L6, L7, L8, L9, and L10 asymmetric rates of the patients were significantly different from those of the normal subjects (P < 0.05); L3, L6, L7 and L10 asymmetric rates were significantly different before and after treatment (P < 0.05). Mandibular indexes including L1, L3, L4, L5, L6, L7, L8, L9, and L10 asymmetric rates were significantly different from normal indicators (P < 0.05); L1, L3, L4, L5, L6, L7, L8, L9, and L10 asymmetric rates changed significantly after treatment (P < 0.05). ConclusionClinical facial asymmetry mainly manifests on the bottom 1/3 part of the face, and facial mandibular asymmetry is the most obvious.
Hemispheric asymmetry is a fundamental organizing principle of the human brain. Answering the genetic effects of the asymmetry is a prerequisite for elucidating developmental mechanisms of brain asymmetries. Multi-modal magnetic resonance imaging (MRI) has provided an important tool for comprehensively interpreting human brain asymmetry and its genetic mechanism. By combining MRI data, individual differences in brain structural asymmetry have been investigated with quantitative genetic brain mapping using gene-heritability. Twins provide a useful natural model for studying the effects of genetics and environment on the brain. Studies based on MRI have found that the asymmetry of human brain structure has a genetic basis. From the perspective of quantitative genetic analysis, this article reviews recent findings on the genetic effects of asymmetry and genetic covariance between hemispheres from three aspects: the asymmetry of heritability, the heritability of asymmetry and the genetic correlation. At last, the article shows the limitations and future research directions in this field. The purpose of this systematic review is to quickly guide researchers to understand the origins and genetic mechanism of interhemispheric differences, and provide a genetic basis for further understanding and exploring individual differences in laterized cognitive behavior.