[Sixteen keys for building a youthful smile].
The present study aims at establishing elements for diagnosis and construction of a harmonious, balanced, desirable and durably young smile. Once the importance of a harmonious smile in today's society has been studied, smile is analyzed under two aspects. One considers it in its own unitary structure, the other in its living immediate environment: the face. Sixteen key rules have been defined to characterize and analyze it. Those various "keys of smile" will enable the practitioner to construct it in positioning the maxillary teeth in a facial balance, thus meeting the criteria of esthetics and appeal so much wanted by our patients. Taking into account the criterion of general aging of the face, the smiles thus realized will remain young for a longer period of time. Three principles of analysis have been used to achieve this task: the observation in "dynamic" situation (as opposed to a "static" frozen study), the reference to particular measurements for each case (as opposed to measurements refering to statistics tables), and the evaluation of the interlabial space at rest of the case considered. This leads to the definition of the measurement of the "golden section dynamic smile" (G.S.D.S.) and a reminder of the measurement of "the constant of ideal smile" (C.I.S.). Adorned with such smiles, our patients will benefit from a real feeling of well-being which they will communicate to their circle of friends and acquaintances for their greatest delight.