Size of the Alveolar Arch of the Mandible in Relation to that of the Maxilla in 45,X Females

Length and width of the alveolar arch of the mandible and maxilla were determined from hard stone casts of 45,X females (Turner syndrome), female first-degree relatives, and population control females. Adjusted mean values (covariance adjusted for age, previous orthodontic treatment, and number of lost permanent teeth) for mandibular arch width were larger in 45,X females than in normal controls, both absolutely and, more clearly, in relation to the maxillary arch. The total absolute length of the mandibular arch was slightly reduced in 45,X females. The broader and shorter alveolar arch of the mandible in relation to the narrower but normal-length maxillary arch reflects imbalanced facial growth in subjects with one X-chromosome instead of the normal two.