A cross-sectional study to correlate nasal profile and chin position with cephalometric lip profile

To determine the effect of the nose and chin on the cephalometric lip profile.

The pre-treatment lateral cephalograms of 177 adult patients with no history of orthodontic treatment were manually traced. The sample size was divided into three vertical and horizontal groups using angle ANB and MMA to assess the difference in nose and chin forms. The horizontal and vertical groups were analyzed using One-way ANOVA and Kruskal-Wallis. The Independent sample t-test and Mann-Whitney U were used for comparison between the two genders. The correlation of nose and chin with E, S line, and nasolabial angle was done using the Spearman correlation coefficient while the effect was assessed using linear regression analysis.

Among the nasal variables, columellar length inversely affects the linear position of the upper lip and this was statistically significant. The nasolabial angle is also affected by the inclination of the nasal base and this was statistically significant. The linear distance of the soft tissue chin in relation to the maxilla has the most effect on the position of the upper lip. It is notable that all hard and soft tissue chin variables inversely affected the linear position of the upper and lower lips.

The quantitative measure of the effect of the nose and chin on lips is important as it allows clinicians to determine the overall effect of adjunctive procedures at pretreatment levels. Thus, corrective procedures such as rhinoplasty or genioplasty can be done at pre-orthodontic treatment stages to create a better treatment plan for patients.