Currently, concern about facial attractiveness is increasing, and this fact has led to orthodontics in adult patients being an increasingly demanded treatment, and with it, multi-disciplinary work. When it is caused by a vertical excess of the maxilla, the ideal solution is orthognathic surgery. However, in borderline cases and when the cause is hyperactivity of the upper lip levator muscle complex, alternative conservative solutions can be considered, such as the application of botulinum toxin A (BTX-A). Botulinum toxin is a protein produced by a bacterium and causes a reduction in the force of muscle contraction. The multi-factorial nature of the smile requires an individualized diagnosis in each patient, since there are multiple ways to treat the gummy smile (orthognathic surgery, gingivoplasty, orthodontic intrusion). In recent years, interest has grown in the simplest techniques that allow the patient to quickly return to their usual routine, such as lip replacement. However, this procedure shows recurrences in the first 6–8 post-operative weeks. The main objective of this systematic review and meta-analysis is to analyze the effectiveness of BTX-A in the treatment of gummy smile in the short term, to study its stability, and to evaluate potential complications. A thorough search of the PubMed, Scopus, Embase, Web of Science, and Cochrane databases and a grey literature search were conducted. The inclusion criteria were studies with a sample size greater than or equal to 10 patients with gingival exposure greater than 2 mm in smile, treated with BTX-A infiltration. Those patients whose exclusive etiology of their gummy smile was related to altered passive eruption, gingival thickening, or overeruption of upper incisors were excluded. In the qualitative analysis, the mean pre-treatment gingival exposure ranged between 3.5 and 7.2 mm, reaching a reduction of up to 6 mm after infiltration with botulinum toxin at 12 weeks. Although multiple muscles are involved in the facial expression, the muscles par excellence selected for blockade with BTX-A were levator labii superioris, levator labii superioris ala nasalis, and zygomaticus minor, infiltrating from 1.25 to 7.5 units per side. In the quantitative analysis, the difference in mean reduction between both groups was −2.51 mm at two weeks and −2.24 mm at three months. The benefit of BTX-A in terms of improvement of gummy smile is demonstrated, as a significant reduction in gummy smile is estimated by BTX-A therapy two weeks after its application. Its results gradually decrease over time, however, they stay satisfactory without returning to their initial values after 12 weeks.

Upper airway changes following bimaxillary advancement surgery to treat obstructive sleep apnea syndrome remain controversial. The main objective of this systematic review and meta-analysis was to investigate the effects of bimaxillary advancement surgery on the upper airway (UA) of obstructive sleep apnea syndrome patients through examining changes three-dimensionally in vertical and supine position and through changes in oximetric variables (AHI, RDI, O2 Sat) and in the quality of life measured by the Epworth sleepiness scale (ESS). A thorough search of the PubMed, Scopus, Embase and Cochrane databases and a grey literature search (Opengrey) were conducted. No limit was placed on publication year or language. The inclusion criteria were: adult obstructive sleep apnea patients who had undergone bimaxillary advancement surgery, three-dimensional CBCT or CT and oximetric measurements and at least six weeks follow-up. Sample sizes of under 10 patients were excluded. Finally, 26 articles were included in the qualitative review and 23 in the meta-analysis. Bimaxillary advancement surgery has been shown to be beneficial in terms of increased upper airway size, improved oximetric indicators and the quality of life measured on the Epworth sleepiness scale.

Due to its aesthetic implications, gummy smile is a common reason for consultation. When it is caused by a vertical excess of the maxilla, the ideal solution is orthognathic surgery. However, in borderline cases and when the cause is hyperactivity of the upper lip levator muscle complex, alternative conservative solutions can be considered, such as the application of botulinum toxin A (BTX-A). The main objective of this systematic review and meta-analysis is to analyze the effectiveness of BTX-A in the treatment of gummy smile in short and medium term, to study its stability and to evaluate potential complications. A thorough search of the PubMed, Scopus, Embase, Web of Science and Cochrane databases and a grey literature search were conducted. The inclusion criteria were: studies with a sample size greater than or equal to 10 patients with gingival exposure greater than 2 millimeters in smile, treated with BTX-A infiltration. The benefit of BTX-A in terms of improvement of gummy smile is demonstrated, a statistically significant reduction in gummy smile is estimated by BTX-A therapy two weeks after its application. Its results gradually decrease over time, however they remain satisfactorily without returning to their initial values ​​after 12 weeks.