Skeletal analysis of craniofacial deformities in brachycephaly: Comparisonwith craniofacial deformities in plagiocephaly

The deformities of craniofacial bones in brachycephaly (n = 2) and plagioce phaly (n = 2) were compared using three-dimensional skull replicas. In brac hycephaly the bilateral deformities of the cranial base were similar to the unilateral deformities on the affected side in plagiocephaly. Shortening o f the anterior-middle cranial fossas and expansion of the middle cranial fo ssas suggest downward and anterior displacement of both temporomandibular ( TM) joints resulting in the underdevelopment of the middle-inferior facial bones, though this is less conspicuous in brachycephaly for three reasons. The most important one is that the patients have an imposing facial morphol ogy characterised by high, protruding facial bones, as found on the affecte d side in plagiocephaly. Secondly, the frontal bones are flattened and posi tioned posteriorly in the anteroposterior direction, which also helps to ma sk the underdevelopment of the middle-inferior facial bones. Finally, as bo ny deformities are symmetrical in brachycephaly, they are not as obvious as they would be if they were unilateral.