Background - A harmonious soft tissue profile, an important treatment goal in orthodontics, is sometimes difficult to achieve, partly because the soft tissue overlying the teeth and bones is highly variable in its thickness. Aim - The aim of this study was to determine influence of first premolar extraction on soft tissue profile in orthodontic patients and possible gender differences between pre- and post-treatment values. Method- Pre-treatment and post-treatment lateral cephalogram of 80 patients were analyzed with respect to linear parameters. A paired samples t test was carried out to know the difference in pre & post treatment measurements of the nine parameters in males and females and unpaired t test was used to know the differences in the pre-treatment & post-treatment measurements in Males & Females. Results- There was statistically significant difference between all the pre-treatment & post treatment parameters. The post-treatment measurements of H angle, soft tissue subnasale to H line, upper-lip strain, E line (Upper & Lower) & Angle of facial convexity decreased significantly (p = <0.001). The post-treatment measurements of Nose prominence, upper-lip thickness, Merrifield’s Z angle increased. Conclusion- The results of this study indicate that there is considerable effect of extraction of first premolars on the soft tissue profile, as suggested by all soft tissue parameters of current study which show significant changes in post-treatment value.
Keywords - First premolar extraction, H Angle, Merrifield’s Z angle, upper-lip thickness.