1. A method for acquiring a 3-Dimensional (3D) image of a set of teeth, comprising: acquiring 3D tooth images of respective teeth of a patient using a Computed Tomography (CT) scan; acquiring a first labial side image which is an optical image in which a set of teeth of the patient is shown; and acquiring a first 3D dentition image which includes the set of teeth of the first labial side image by integrating the 3D tooth images with the first labial side image and arranging the 3D tooth images in conformity with the set of teeth of the first labial side image.