Relations of laterality and chewing sidedness in twins

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p><em>Objectives:</em> To study, whether there are associations between chewing side preference and other lateralities, whether there is a genetic origin for preferred chewing side (PCS), relations to sex, birth order and orthodontic treatment.</p><p><em>Materials and Methods:</em> The study included 113 twin pairs, 57 pairs monozygotic, 47 pairs same sex dizygotic and 9 pairs of opposite sex. The lateralities of preferred chewing side, footedness and eyedness were assessed by functional tests and handedness was checked by asking.</p><p><em>Results:</em> Right-handed, -footed and -eyed as separated groups, and true-right sided (combined), were evenly distributed by preferred chewing side. By contrast, left-handed, -footed, -eyed and non-right sided used more left or both sides when chewing. Birth order affected preferred chewing side among monozygotic: the first-born twin was more likely to have the preferred chewing side on the non-right, whereas second-born twins used right side. Gender, zygosity and orthodontic treatment were not statistically significant factors.</p><p><em>Limitations:</em> Examination of chewing sidedness could have been done in several different ways to provide a definite result. Sample size of opposite sex twins was very small.</p><p><em>Conclusions:</em> Preferred chewing side generally seemed to follow the side where other lateralities occur; however, monozygotic twins seemed to be more receptive to it. True-right sided were more evenly distributed than non-right sided by the preferred chewing side.</p></div>