{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,17]],"date-time":"2026-03-17T12:03:22Z","timestamp":1773749002684,"version":"3.50.1"},"reference-count":24,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,3,17]],"date-time":"2026-03-17T00:00:00Z","timestamp":1773705600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Toxins"],"abstract":"<jats:p>Excessive gingival display (EGD) is most commonly attributed to vertical upper lip elevation, short lip length, or dentoalveolar disproportion. However, some patients exhibit gingival or mucosal visibility during smiling despite minimal vertical upper lip displacement, suggesting the presence of alternative dynamic patterns. This exploratory case series examined an inversion-dominant smile presentation and its documented modulation in association with conservative intraoral chemodenervation directed toward the marginal region of the orbicularis oris. Ninety-four patients with dynamic inversion during smiling were assessed using a qualitative rating aid (Armenti Inversion Scale, AIS) and a quantitative composite proportional measure of vermilion loss (\u0394Lv%). All patients received low-dose intraoral Onabotulinum toxin A (4\u20136 U) as part of routine aesthetic care. At Day 15 follow-up, a shift toward lower inversion grades was observed across the cohort, with a large proportion of patients showing minimal residual inversion. Quantitative \u0394Lv% values showed proportional changes that were directionally consistent with shifts in AIS grade. The functional alterations were mild, transient, and self-resolving. Preliminary inter-rater agreement for AIS and measurement repeatability for \u0394Lv% suggested acceptable internal consistency for exploratory reporting tools. These findings suggest that inward vermilion inversion may represent a potentially distinct dynamic contributor to gingival or mucosal exposure in selected individuals, and that conservative marginal chemodenervation was associated with transient modulation of this pattern with generally preserved oral competence. AIS and \u0394Lv% are preliminary documentation tools. Further studies incorporating objective neuromuscular assessment, three-dimensional imaging, and comparative designs are required to refine phenotypic characterization.<\/jats:p>","DOI":"10.3390\/toxins18030146","type":"journal-article","created":{"date-parts":[[2026,3,17]],"date-time":"2026-03-17T09:35:57Z","timestamp":1773740157000},"page":"146","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Marginal Orbicularis Oris Hyperactivity (MOOH): An Exploratory Case Series of Inversion-Dominant Upper Lip Dynamics Following Intraoral Botulinum Toxin Type A"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-8139-9169","authenticated-orcid":false,"given":"Andrea Felice","family":"Armenti","sequence":"first","affiliation":[{"name":"LA VISION Training Institute, Via Magenta, 5, 00185 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,17]]},"reference":[{"key":"ref_1","first-page":"809","article-title":"Excessive gingival display: Etiology, diagnosis, and treatment modalities","volume":"40","author":"Silberberg","year":"2009","journal-title":"Quintessence Int."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"26","DOI":"10.4067\/S0719-01072017000100026","article-title":"The treatment of gummy smile: Integrative review of literature","volume":"10","author":"Moura","year":"2017","journal-title":"Rev. Clin. Periodoncia Implantol. Rehabil. Oral"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Maleki, M., Huang, B., Mendes, V.C., Caminiti, M.F., and Finer, Y. (2024). A Systematic Review and Meta-Analysis Comparing Surgical and Nonsurgical Treatments for Excessive Gingival Display. Dent. J., 12.","DOI":"10.3390\/dj12060154"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1093\/asj\/sjv082","article-title":"Botulinum toxin for the treatment of excessive gingival display: A systematic review","volume":"36","author":"Nasr","year":"2016","journal-title":"Aesthet. Surg. J."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"432","DOI":"10.1177\/1090820X14527603","article-title":"OnabotulinumtoxinA for the treatment of a \u201cgummy smile\u201d","volume":"34","author":"Suber","year":"2014","journal-title":"Aesthet. Surg. J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"e717","DOI":"10.1016\/j.jormas.2022.05.016","article-title":"Botulinum toxin type A for the treatment of excessive gingival display: A systematic review","volume":"123","author":"Rasteau","year":"2022","journal-title":"J. Stomatol. Oral Maxillofac. Surg."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"e273","DOI":"10.1097\/SCS.0000000000007128","article-title":"Botulinum toxin type A for lip augmentation: The \u201clip flip\u201d","volume":"32","author":"Teixeira","year":"2021","journal-title":"J. Craniofac. Surg."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Hong, S.O. (2023). Cosmetic Treatment Using Botulinum Toxin in the Oral and Maxillofacial Area: A Narrative Review of Esthetic Techniques. Toxins, 15.","DOI":"10.3390\/toxins15020082"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Angulo-Manzaneque, C., Baus-Dom\u00ednguez, M., Ruiz-de-Le\u00f3n, G., Serrera-Figallo, M.-\u00c1., Aguilera, F.S., and Torres-Lagares, D. (2024). Proposal of a new therapeutic classification in gingival smiles focused on treatment with semi-permanent infiltrations. Dent. J., 12.","DOI":"10.3390\/dj12100319"},{"key":"ref_10","first-page":"110471","article-title":"A biomechanical modeling study of the orbicularis oris and jaw posture effect on lip shape","volume":"122","author":"Stavness","year":"2021","journal-title":"J. Biomech."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"429","DOI":"10.1055\/s-0045-1809151","article-title":"Impact of hyaluronic acid lip filling on the electromyographic activity of the orbicularis oris muscle in adult women","volume":"58","author":"Bettiol","year":"2025","journal-title":"Indian J. Plast. Surg."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"853","DOI":"10.5114\/ada.2019.82795","article-title":"The whole truth about botulinum toxin\u2014A review","volume":"37","author":"Witmanowski","year":"2020","journal-title":"Postepy Dermatol. Alergol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1477","DOI":"10.1589\/jpts.30.1477","article-title":"Comparison of orbicularis oris muscle strength and endurance in young and elderly adults","volume":"30","author":"Park","year":"2018","journal-title":"J. Phys. Ther. Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"e70590","DOI":"10.1111\/jocd.70590","article-title":"The aging process of facial muscles","volume":"24","author":"Yi","year":"2025","journal-title":"J. Cosmet. Dermatol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"981","DOI":"10.1185\/030079904125003962","article-title":"Safety of botulinum toxin type A: A systematic review and meta-analysis","volume":"20","author":"Naumann","year":"2004","journal-title":"Curr. Med. Res. Opin."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1097\/SAP.0000000000002994","article-title":"Long-term effects of repeated botulinum toxin injection in cosmetic therapeutics","volume":"88","author":"Crook","year":"2022","journal-title":"Ann. Plast. Surg."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1451","DOI":"10.1080\/00207450590956576","article-title":"Botulinum toxin: From spasticity reliever to a neuromotor re-learning tool","volume":"115","author":"Krishnan","year":"2005","journal-title":"Int. J. Neurosci."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Hara, T., Momosaki, R., Niimi, M., Yamada, N., Hara, H., and Abo, M. (2019). Botulinum toxin therapy combined with rehabilitation for stroke: A systematic review of effect on motor function. Toxins, 11.","DOI":"10.3390\/toxins11120707"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1016\/j.ajodo.2007.04.033","article-title":"Botulinum toxin type A (Botox) for the neuromuscular correction of excessive gingival display on smiling (gummy smile)","volume":"133","author":"Polo","year":"2008","journal-title":"Am. J. Orthod. Dentofacial Orthop."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"70","DOI":"10.2319\/091407-437.1","article-title":"Surface anatomy of the lip elevator muscles for the treatment of gummy smile using botulinum toxin","volume":"79","author":"Hwang","year":"2009","journal-title":"Angle Orthod."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1042","DOI":"10.1016\/j.jaad.2010.02.053","article-title":"Gummy smile and botulinum toxin: A new approach based on the gingival exposure area","volume":"63","author":"Mazzuco","year":"2010","journal-title":"J. Am. Acad. Dermatol."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Rojo-Sanchis, C., Montiel-Company, J.M., Tarazona-\u00c1lvarez, B., Haas-Junior, O.L., Peir\u00f3-Guijarro, M.A., Paredes-Gallardo, V., and Guijarro-Mart\u00ednez, R. (2023). Non-surgical management of the gingival smile with botulinum toxin type A: A systematic review and meta-analysis. J. Clin. Med., 12.","DOI":"10.3390\/jcm12041433"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"108058","DOI":"10.1016\/j.toxicon.2024.108058","article-title":"Dose and injection site of botulinum toxin type A for gummy smile management: A systematic review and bibliometric analysis","volume":"249","author":"Wang","year":"2024","journal-title":"Toxicon"},{"key":"ref_24","first-page":"248","article-title":"Gummy smile correction using botulinum toxin with respective gingival surgery","volume":"19","author":"Pedron","year":"2018","journal-title":"J. Dent."}],"container-title":["Toxins"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-6651\/18\/3\/146\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,17]],"date-time":"2026-03-17T11:14:36Z","timestamp":1773746076000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-6651\/18\/3\/146"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,17]]},"references-count":24,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["toxins18030146"],"URL":"https:\/\/doi.org\/10.3390\/toxins18030146","relation":{},"ISSN":["2072-6651"],"issn-type":[{"value":"2072-6651","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,17]]}}}