Upper incisor to Soft Tissue Plane (UI-STP): a new reference for diagnosis and planning in dentofacial deformities

Planning in orthognathic surgery has been and still is an open issue. We have evolved from 2D classical cephalometric hard-tissue planning to 2D soft tissue planning, and finally to 3D and hard and soft tissue evaluation. This, to our knowledge, is the first description of a new Soft Tissue Plane (STP) and its relationship with the anterior position of the upper incisor (UI). Profile photographs of 110 "attractive individuals" with lips at rest or smiling and with upper incisor shown were used. The photographs used were of 65 professional models from two international agencies and 45 individuals considered most attractive in the internet forums, which included catwalk models and actors. In 86 cases (78.18 %), the incisor was located in front of the STP (A). In 15 cases (13.63%), it was on the plane (N); and in the remaining 9 cases (8.18%), it was behind (P). Despite the limitations of this study and based on our series, we can conclude that the upper incisor is located at or in front of the Soft Tissue Plane (STP) in 91.81% of the attractive facial profiles studied. On the other hand, the relative position of the upper incisor to the soft tissue plane (UI-STP) could be a useful diagnostic and planning tool in orthodontic and surgical management of dentofacial deformities.