Measurements of lip lines while smiling

We used the preoperative and postoperative photographs of the patients while smiling to measure the difference in the vertical distance of the lips. At first, the observer adjusted the whole size of photographs according to the distant reference of CT. The photographs were collected using V-Ceph ver. 6.0 (OSSTEM IMPLANT Co., Seoul, Republic of Korea) software. The same program was used to measure the patients’ right and left lateral canthus distances (lateral intercanthus distance). The preoperative photograph was adjusted based on these distances and the lateral intercanthus distance that was measured on the preoperative CT image (Fig. 2a). At second, using the firstly revised picture, we measured the vertical distance from the line (lateral intercanthus line) that connects the right and left lateral canthus to the edge of the maxillary central incisors in V-Ceph. We also measured the vertical distance from the edge of the maxillary central incisors to the intercanthus horizontal plane on the preoperative CT. Then finally, we altered the vertical size of the smile picture (the firstly revised picture) that was adjusted using the intercanthus distance to have the same vertical distance from the lateral intercanthus line to the central incisors as those vertical distance from the intercanthus horizontal plane to the central incisors measured on the preoperative CT data (Fig. 2b). The alteration of the photograph was completed in the state of the same value of the lateral intercanthus distance and the vertical distance from incisor to the lateral intercanthus line.

Calibration of a clinical picture of a patient’s smile according to the 3D CT image (e.g., preoperative image). a 2D photograph; b 3D CT image. At first, the lateral intercanthus distance (white α) in the smile picture matched that (white α’) in the 3D CT image. The vertical ratio of the photograph was modified by adjusting the vertical distance (black β) from the lateral intercanthus line to the anterior tooth in the smile picture to match that (black β’) in the 3D CT image. The vertical distance of the lips during smiling, which is the shortest distance (blue line) from the lateral intercanthus line (red line) to the mouth corner in the photograph

We measured the vertical distance of the lips during smiling, which is the shortest distance from the lateral intercanthus line to the mouth corner. The difference between the right and left vertical distances was defined as canting. The angle between the line that connects the left and right mouth corners and the lateral intercanthus line was defined as the slope angle while smiling. We acquired preoperative and postoperative data by editing the preoperative and postoperative smile pictures via the same procedure. We also calculated the magnitude of change after surgery.