Developmental Relationship Between Premaxillary-Maxillary Suture Patency and Anterior Nasal Spine Morphology

Abstract

An important factor in determining the bony morphology of the human nasal capsule is the area of the antero-inferior region of the car-tilaginous 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 midfa-cial 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 < 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 < 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 midfa-cial growth. Among the proposed mechanisms for early midfacial growth (i.e. , advancement), a traction hypothesis involving the septal cartilage and the septo—premaxillary ligament (SPL) has been suggested (Scott, 1953; Sarnat and Wexler, 1966; Latham, 1970; Gange and Johnson, 1974; Sie— gel et a1, 1985). Previous work with histologi-cal preparations of human cleft and normal fetuses suggests a relation between the lack of prenatal midfacial advancement and the disrup— tion of both the septo-premaxillary ligament and the labio—septo-premaxillary (LSP) regions (in— Mr.