The Dentate Esthetic Functional Space Ruler (DEFSR) measures the vertical distance from the undisplaced vestibule to the incisal edges of the maxillary and mandibular teeth and its relationship to the lip at repose and/or smiling. The amount of tooth exposed below and above the upper and lower teeth in contrast to the facial drape at rest and smiling will provide the visible reference in planning the final prosthetic restoration.
In addition to taking measurements at rest, there is a need to measure a patient’s upper lip when smiling. By doing so, the practitioner then has information to compare to the resting lip. If a patient has a short lower lip, or a strong smiling lip, excessive and unaesthetic gingival tissue may be visible if the wrong size implant or tooth is used in the prosthesis. Understanding the spacial relationships between the maxillary ridge, resting lips, and the smiling lips will provide a predictable, esthetic prosthesis with a more natural look for each unique patient.