Background: The soft tissue thickness is affected by anterior posterior skeletal relationship. This study has been designed to evaluate the soft tissue thickness among different anterior posterior skeletal classifications.

Material and Methods: In this cross-sectional study, 206 digital lateral cephalometric radiographs from patients undergoing treatment at several orthodontic clinics were evaluated. The skeletal group was determined by the ANB angle. The planned points were determined on digital radiographs using the Digimizer.V4.1.1.0 and then the measurements were done. Data were analyzed by Kruskal-Wallis, Mann-Whitney, Pearson Correlation and Spearman tests.

Results: Significant difference showed between soft tissue thickness at Subnasale between class I and II, at Subnasale, Labrale Superius, Stomion Superius, Stomion Inferius between class I and III and at Subnasale, Labrale Superius, Stomion Superius, Stomion Inferius, between class II and III. Among the women, soft tissue thickness at subnasale were higher in class I group compared to class II, Subnasale, Labrale Superius, Stomion Superius, Stomion Inferius were higher in class III compared to class I and at Labrale Inferius was higher in class II compared to class III. Among the men, soft tissue thickness at Stomion Superius, Stomion Inferius and Labrale Superius were higher in class III group compared to class I and II.

Conclusion: We established that soft tissue thickness in some landmarks were significantly different between skeletal groups and gender. There is a correlation in soft tissue thickness and skeletal relationship at Stomion Inferius, Subnasale, Labrale Superius, Stomion Superius.

Keywords: Soft Tissue, Skeletal Classification, Cephalometry