Abstract: Objective: This study is aimed to analyze the morphology of soft tissue profile in adult skeletal Class III malocclusion. Methods: 53 adult patients (female 32, male 21) with skeletal Class III malocclusion and 53 adult patients with skeletal Class I malocclusion were taken cone beam CT (CBCT) before treatment, the lateral cephalometric radiographs were rebuilt by Dolphin imaging 11.0 and measured using soft tissue analysis of Holdaway. The results were divided into different groups based on gender and sagittal skeletal pattern. Statistical analysis was carried out with SPSS 20.0. Results: The skeletal Class III patients had sunken mid facial soft tissue (skeletal profile convexity, Sn - H line), protrusive upper lip (upper lip sulcus depth, upper lip strain measurement), protrusive lower lip (Li – H line), protrusive chin and shallow mentolabial sulcus (soft tissue facial angle, H angle, mentolabial sulcus depth, soft tissue chin thickness) compared to adult skeletal Class I malocclusion. The differences of soft tissue profile in adult skeletal Class III malocclusion between different genders were among soft tissue facial angle, upper lip sulcus depth and upper lip strain measurement. These differences revealed that females had better soft tissue compensation. Conclusion: Because of the inharmonious relationship between jaws, the soft tissue profile in adult skeletal Class III patients has remarkable different features compared with skeletal Class I patients. Orthodontists should know these features well in order to make more suitable and comprehensive treatment plan and improve the dissatisfactory soft tissue profile in skeletal Class III patients.

Key words: adult class III, soft tissue, Holdaway analyze, CBCT