Developmental relationship between premaxillary-maxillary suture patency and anterior nasal spine morphology.

An important factor in determining the bony morphology of the human nasal capsule is the area of the antero-inferior region of the cartilaginous septum at the level of the anterior nasal spine (ANS). Since man is unique among mammals and the primates in developing an anterior nasal spine, the present study was designed to learn more about ANS morphology and its developmental relationships to other midfacial structures. Since well documented racial differences exist in ANS morphology and facial prognathism between black and white populations, developmental osteologic data from these groups were used to examine premaxillary morphology. Cleaned and dried skulls from 93 black and 97 white specimens, ranging in age from 8 weeks prenatally to 8 years, were examined to assess ANS morphology and premaxillary-maxillary suture status. Chi-square analysis reveals that white specimens exhibit a significantly (p less than 0.05) higher frequency of fused or fusing premaxillary-maxillary sutures and a more prominant ANS compared to black specimens by 24 weeks prenatally. Significant (p less than 0.001) relationships are also noted between the degree of suture fusion and ANS prominance. Findings from the present study suggest that the distinctive racial variations in midfacial profiles are established early in fetal development (by the second trimester) and maintained postnatally. Results from the present study also appear consonant with associations predicted by a septal-mediated traction model of midfacial growth.