The Vertical Changes of Lip and Perioral Soft Tissue Following Orthognathic Surgery in Skeletal Class III Patients by a Cephalometric Analysis of Cone Beam Computed Tomography

ABSTRACT

PURPOSE: The aim of this study is to evaluate the vertical changes of the lip and perioral soft tissue, following orthognathic surgery in skeletal class III patients by a cephalometric analysis of a cone beam computed tomography (CBCT).METHODS: A total of 20 skeletal class III patients, who had bimaxillary surgery with Le Fort 1 osteotomy and bilateral sagittal split ramus osteotomy, were included in this study. The surgical plan for maxilla was posterosuperior impaction with the anterior nasal spine, as the rotation center. Further, the surgical plan for mandible was also posterosuperior movement. The soft tissue changes between lateral cephalogram and CBCT were compared. And the correlations between independent variables and dependent variables were evaluated.RESULTS: There were no significant differences of the soft tissues changes between lateral cephalogram and CBCT. Upper lip philtrum length (SnLs), nasolabial angle increased and upper lip vermilion length (LsStms), lower lip length (StmiB'), lower lip vermilion length (StmiLi), lower lip philtrum length (LiB') and soft tissue lower facial height (SnMe') decreased after surgery. Change of SnLs (DeltaSnLs) was influenced by vertical change of menton (DeltaMeV), and change of LsStms (DeltaLsStms) was influenced by upper lip thickness (ULT). Change of StmiLi' (DeltaStmiLi') were influenced by preoperative overjet. Change of StmiB' (DeltaStmiB') were influenced by preoperative overjet, vertical change of lower incisor (DeltaL1V) and horizontal change of posterior nasal spine (DeltaPNSH). Change of LiB' (DeltaLiB') was influenced by DeltaL1V and DeltaPNSH. Change of SnMe' (DeltaSnMe') was influenced by DeltaMeV, horizontal change of upper incisor (DeltaU1H) and horizontal change of lower incisor (DeltaL1H). DeltaNasolabial angle was influenced by change of ULT (DeltaULT).CONCLUSION: Both soft tissues and hard tissues can be evaluated by CBCT. Posterosuperior rotation of maxillomandibular complex resulted in increase of upper lip philtrum length and nasolabial angle, while the upper lip vermilion length, lower lip philtrum length, lower lip vermilion length, and soft tissue lower facial height showed a decrease.