Soft tissue Cephalometric Norms for Orthognathic Surgery

Cephalometric norms are different for different ethnie groups. They help making the deformity assessment and surgical planning procedures more appropriate for a particular individual. Hence, the present study was aimed at the development of the soft tissue cephalometric norms for orthognathic surgery for north India.The study sample consisted of fifty adult males and fifty adult females. Standardized lateral cephalogram was taken, traced and analysed for each subject. The statistical analysis involved calculation of mean and standard deviation for thirteen parameters. This data was compared with that reported by Legan and co-workersl using Normal (z) test. Male and female subjects were also compared with each other.For male subjects, all the parameters except facial convexity angle, lower vertical height to depth ratio, nasolabial angle and vertical lip chin ratio; the statistical difference varied from highly significant to most highly significant.For female subjects, fïve parameters viz. facial convexity angle, maxillary prognathism, lower vertical height to depth ratio, nasolabial angle and maximum incisor exposure have not been found to be significantly different from Legan and co-worker's datai. For all the remaining parameters, the statistical difference varied from highly significant to most highly significant. Comparison between male and females also led to distinctive differences.The soft tissue cephalometric norms for orthognathic surgery were derived for the population of eastern Uttar Pradesh region of north India. Hence, while planning combined orthodontic-orthognathic surgical approach for this particular population, it appears more appropriate to use the norms as developed or modified in the present study.