Craniofacial asymmetry in development: an anatomical study

The purpose of this study was to evaluate the occurrence of craniofacial asymmetries in four areas of human skulls of various age groups to test the hypothesis that there is craniofacial symmetry before the chewing habit is established. The data were obtained from 95 skulls of fetuses, infants, children, and adults, from the collection of Federal University of São Paulo. The following measurements were taken on each skull with a digital caliper: from the infraorbital foramen to the anterior nasal spine (IOF); from the greater palatine foramen to the posterior nasal spine (GPF); from the spinous foramen to the basion (SF); and from the spinous foramen to the zygomatic arch (ZA). On different occasions, each measurement was taken three times on both sides of the skull in random order. The mean of the right-side measurements were subtracted from the mean of the left-side measurements, and the differences were transformed into percentages. Comparisons were made by analysis of variance. The presence of cranial asymmetry was statistically significant throughout the whole sample. The minimum value found was 2.8% and the maximum 6.5%. All age groups presented the same degree of asymmetry of distances IOF, GPF, and SF. The group of infants presented a higher degree of asymmetry on distance ZA, followed by the groups of fetuses, children, and adults. This study confirmed statistically significant craniofacial asymmetry in fetuses and infants (before dentition). Therefore, the hypothesis that craniofacial asymmetry only appears after establishment of the chewing habit was not supported.