Smile analysis in different facial patterns and its correlation with underlying hard tissues

BACKGROUND The subject's inherent growth pattern can be an effective factor in characteristics of smile. More vertical growth in the posterior maxilla than in the anterior maxilla could result in a changed relationship between the occlusal plane and the curvature of the lower lip upon smile. In order to broaden the understanding of how smile gets affected by growth pattern and the underlying hard tissues, the present study was undertaken to compare smile in various growth patterns, to determine sexual dimorphism, if any; as well as to correlate smile with underlying hard tissues. METHODS One hundred and fifty subjects were selected amongst the students in the Dental Institute and from the outpatient department of Department Orthodontics and Dentofacial Orthopedics. Sample selected for the study ranged in the age group of 17 to 25 years. Selected individuals were subjected to lateral head cephalometric radiography in the Department of Oral Medicine and Radiology and videography. Cephalograms were traced and the subjects were divided into horizontal, average, and vertical growth pattern on the basis of GoGn-SN, lower anterior facial height, and Jaraback's ratio. The video clip was downloaded to obtain frame of posed smile. Cephalometric and photographic measurements were recorded and subjected to statistical analysis. RESULTS The mean values of smile parameters were significantly higher in males as compared to females irrespective of the growth pattern. The mean incisal display, interlabial gap, lower lip to incisal edge distance, upper vertical lip length, and occlusal plane angle was highest in both males and females of vertical facial growth pattern group; whereas, the smile index, posterior corridor (left and right) were less in vertical facial growth pattern group in both males and females. Thus, the parameters in vertical dimension were increased in vertical growers whereas, the parameters in transverse dimension decreased. CONCLUSIONS The facial growth pattern has significant influence on the parameters of smile along with definite sexual dimorphism. The angular and linear parameters, except saddle angle and lower incisor to NB (linear and angular), influenced smile.