Gummy Smile: Comparison Between Botulinum Toxin, Lip Repositioning Surgery and Combined Techniques in Cases of Lip Hypermobility—A Systematic Review

Background: Excessive gingival display is frequently associated with upper lip hypermobility and represents a common aesthetic concern. Several therapeutic approaches have been proposed, including botulinum toxin type A injections, lip repositioning surgery (LRS), and combined techniques; however, no clear consensus exists regarding the most effective and stable treatment option. Methods: A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA) guidelines. A comprehensive search of multiple electronic databases was performed, leading to the inclusion of 17 human studies that met predefined PICOS criteria. The review protocol was registered in PROSPERO (CRD420261281920). Results: Most included studies reported favorable outcomes in terms of reduction in gingival display, improvement in smile aesthetics, and patient satisfaction. No major adverse effects were reported, suggesting acceptable safety profiles for all therapeutic modalities. Outcomes varied depending on the type of intervention, surgical technique, botulinum toxin dosage and injection protocol, and the initial severity of upper lip hypermobility. Conclusions: Both botulinum toxin injections and LRS demonstrated effectiveness in reducing excessive gingival display. Botulinum toxin provided a rapid but temporary improvement, whereas modified LRS showed greater stability over time. Combined approaches appeared to offer the most consistent long-term results by limiting postoperative relapse. Further standardized protocols and long-term clinical studies are needed to confirm these findings and support evidence-based clinical decision-making.