The gingival complex plays a major role in the overall beauty of a smile. To predictably achieve a successful aesthetic and functional result, the dentist must be able to precisely pre- dict the treatment outcome based on biologic determinants. The diagnosis and treatment of the “gummy smile” help the periodontist to provide the patients with the most beauti- ful smile possible. The nature of a high smile-line can be: dento-gingival, muscular, dento-alveolar (skeletal) or of a mixed nature. Excessive gingival display, frequently seen in adults and resul- ting in short clinical crowns, has been described in the lite- rature as “altered passive eruption”. It exists in adults when the gingival unit remains positioned on the convex promi- nence of the enamel rather than at or in proximity of the cemento-enamel junction.