The role of botulinum toxin A in the management of different types of excessive gingival display: a systematic review.

Background An aesthetic smile displays a symmetrical 2 mm or less of gingival tissue. A smile with over 3 mm of gingival display can be deemed socially unaesthetic, impacting on a patient's psychosocial status. This literature review aimed to explore the role of botulinum toxin A as a treatment modality for different types of excessive gingival display (EGD) and appropriate treatment protocols.Methods A systematic search of the literature dating from 1980 onwards was conducted using electronic databases (Medline, Scopus and Web of Science). The Fowkes and Fulton quality assessment was undertaken to review the level of bias.Results Nine prospective studies were assessed for the number and site of injections, the unit dosage, the reconstitution and the improvement of EGD. Guidelines for treatment of EGD were constructed for operator consideration.Conclusions The data from this study elucidated that botulinum toxin is an effective treatment for all types of EGD caused by hyperfunctional smile muscles. It can be regarded as a safe treatment that reversibly improves facial aesthetics in patients suffering from gummy smile due to hyperactive musculature. Botulinum toxin was confirmed to be useful as a diagnostic tool and palliative treatment, as well as an adjunctive therapy in the treatment of a gummy smile.