{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T21:08:27Z","timestamp":1790197707711,"version":"4.1.0"},"reference-count":31,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T00:00:00Z","timestamp":1766448000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biomimetics"],"abstract":"<jats:p>Background: Impaired mucus drainage from the paranasal sinuses is often associated with nasal obstruction and reduced airway function in growing patients. Orthopedic maxillary protraction and expansion techniques can enhance airway dynamics, but their underlying fluid\u2013structure mechanisms remain insufficiently understood. Objective: To validate that the Right Angle Maxillary Protraction Appliance (RAMPA), combined with a semi-rapid maxillary expansion (sRME) intraoral device gHu-1, improves mucus drainage by enhancing nasal airflow through nasal cavity expansion. Methods: The effects of RAMPA therapy were analyzed using computational fluid dynamics (CFD) for single-phase (air) and two-phase (air\u2013mucus) flows within the nasal cavity, employing the unsteady RANS turbulence model. Finite element method (FEM) results from prior studies were synthesized to assess changes in the center and radius of maxillary rotation induced by RAMPA-assisted sRME. A male patient (aged 8 years 7 months to 11 years 7 months) treated with extraoral RAMPA and the intraoral appliance (gHu-1) underwent pre- and post-treatment cone-beam computed tomography (CBCT) and ear, nose, and throat (ENT) evaluation. Results: FEM analysis revealed an increased radius and elevated center of maxillary rotation, producing expansion that was more parallel to the palatal plane. CFD simulations showed that nasal cavity expansion increased airflow velocity and pressure drop, enhancing the suction effect that promotes mucus clearance from the frontal sinus. Clinically, nasal passages widened, paranasal opacities resolved, and occlusal and intermolar widths improved. Conclusions: RAMPA combined with sRME improves nasal airflow and maxillary skeletal expansion, facilitating paranasal mucus clearance and offering a promising adjunctive approach for enhancing upper airway function in growing patients.<\/jats:p>","DOI":"10.3390\/biomimetics11010005","type":"journal-article","created":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T14:05:22Z","timestamp":1766498722000},"page":"5","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Impact of RAMPA Therapy on Nasal Cavity Expansion and Paranasal Drainage: Fluid Mechanics Analysis, CAE Simulation, and a Case Study"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2523-7509","authenticated-orcid":false,"given":"Mohammad","family":"Moshfeghi","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Sogang University, Seoul 04107, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yasushi","family":"Mitani","sequence":"additional","affiliation":[{"name":"Codomo Clinic, Tokyo 180-0004, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuko","family":"Okai-Kojima","sequence":"additional","affiliation":[{"name":"Children and Women Dental Clinic, Tokyo 106-0046, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bumkyoo","family":"Choi","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Sogang University, Seoul 04107, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1007\/BF02178726","article-title":"Die Gaumennahtsprengung","volume":"14","author":"Derichsweiler","year":"1953","journal-title":"Fortschr. Kieferorthop."},{"key":"ref_2","first-page":"266","article-title":"The apical base after rapid spreading of the maxillary bones","volume":"32","author":"Gerlach","year":"1956","journal-title":"Trans. Eur. Orthod. Soc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"301","DOI":"10.1038\/sj.bdj.4803996","article-title":"Semi-rapid maxillary expansion","volume":"143","author":"Mew","year":"1977","journal-title":"Br. Dent. J."},{"key":"ref_4","first-page":"71","article-title":"Semirapid maxillary expansion\u2014A study of long-term transverse effects in older adolescents and adults","volume":"74","author":"Iseri","year":"2004","journal-title":"Angle Orthod."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1016\/j.ajodo.2011.08.025","article-title":"Improvement of nasal airway ventilation after rapid maxillary expansion evaluated with computational fluid dynamics","volume":"141","author":"Iwasaki","year":"2012","journal-title":"Am. J. Orthod. Dentofac. Orthop."},{"key":"ref_6","first-page":"492","article-title":"Dimensional changes of upper airway after rapid maxillary expansion: A prospective cone-beam computed tomography study","volume":"143","author":"Yoon","year":"2013","journal-title":"Am. J. Orthod. Dentofac. Orthop."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"581","DOI":"10.1016\/j.ijom.2013.11.002","article-title":"Volumetric upper airway assessment in patients with transverse maxillary deficiency after surgically assisted rapid maxillary expansion","volume":"43","author":"Monnazzi","year":"2014","journal-title":"Int. J. Oral Maxillofac. Surg."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"139","DOI":"10.5005\/jp-journals-10005-1069","article-title":"Maxillary expansion","volume":"3","author":"Agarwal","year":"2010","journal-title":"Int. J. Clin. Pediatr. Dent."},{"key":"ref_9","first-page":"2423","article-title":"Protraction effect of RAMPA on maxillae, upper airway and hyoid bone position; finite element analysis","volume":"2","author":"Choi","year":"2018","journal-title":"Biomed. J. Sci. Tech. Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"722","DOI":"10.1080\/10255842.2018.1514498","article-title":"Anterosuperior protraction of maxillae using the extra-oral device, RAMPA; finite element method","volume":"21","author":"Mitani","year":"2018","journal-title":"Comput. Methods Biomech. Biomed. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"804","DOI":"10.2319\/020521-106.1","article-title":"Finite element simulations of the effects of an extra-oral device, RAMPA, on anterosuperior protraction of the maxilla and comparison with gHu-1 intraoral device","volume":"91","author":"Moshfeghi","year":"2021","journal-title":"Angle Orthod."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1099","DOI":"10.1080\/10255842.2021.2001803","article-title":"Finite element and clinical analyses of effects of a new intraoral device (VomPress) combined with extra-oral RAMPA on improving the overjet of craniofacial complex","volume":"25","author":"Mitani","year":"2022","journal-title":"Comput. Methods Biomech. Biomed. Eng."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Moshfeghi, M., Mitani, Y., Okai-Kojima, Y., Choi, B., and Emamy, P. (2025). RAMPA therapy: Impact of suture stiffness on the anterosuperior protraction of maxillae; finite element analysis. Oral, 5.","DOI":"10.3390\/oral5040074"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"20220028","DOI":"10.1098\/rsfs.2022.0028","article-title":"Mucus from human bronchial epithelial cultures: Rheology and adhesion across length scales","volume":"12","author":"Jory","year":"2022","journal-title":"Interface Focus"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"923","DOI":"10.4081\/mrm.2023.923","article-title":"Experimental studies and mathematical modelling of the viscoelastic rheology of tracheobronchial mucus from respiratory-healthy patients","volume":"18","author":"Tauwald","year":"2023","journal-title":"Multidiscip. Respir. Med."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"021011","DOI":"10.1115\/1.4048474","article-title":"Effect of non-Newtonian dynamics on the clearance of mucus from bifurcating lung airway models","volume":"143","author":"Rajendran","year":"2021","journal-title":"J. Biomech. Eng."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"043108","DOI":"10.1063\/5.0202508","article-title":"Highly distinctive linear and nonlinear rheological behaviours of mucin-based protein solutions as simulated normal and asthmatic human airway mucus","volume":"36","author":"Liu","year":"2024","journal-title":"Phys. Fluids"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1016\/j.jbiomech.2019.01.036","article-title":"Non-identifiability of parameters for a class of shear-thinning rheological models, with implications for haematological fluid dynamics","volume":"85","author":"Gallagher","year":"2019","journal-title":"J. Biomech."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Tretiakow, D., Witkowska, E., and Skorek, A. (2022). Maxillary sinus aeration analysis using computational fluid dynamics. PLoS ONE, 17.","DOI":"10.1038\/s41598-022-14342-3"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1343","DOI":"10.1007\/s10237-025-01971-6","article-title":"Increasing Airflow Ventilation in a nasal maxillary ostium using optimised shape and pulsating flows","volume":"24","author":"Fletcher","year":"2025","journal-title":"Biomech. Model. Mechanobiol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"253","DOI":"10.1007\/s10237-022-01645-7","article-title":"Numerical investigation of mucociliary clearance using power law and thixotropic mucus layers under discrete and continuous cilia motion","volume":"22","author":"Modaresi","year":"2023","journal-title":"Biomech. Model. Mechanobiol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"306","DOI":"10.4168\/aair.2019.11.3.306","article-title":"Influence of intranasal drugs on human nasal mucociliary clearance and ciliary beat frequency","volume":"11","author":"Jiao","year":"2019","journal-title":"Allergy Asthma Immunol. Res."},{"key":"ref_23","first-page":"663","article-title":"Effect of accessory ostia on maxillary sinus ventilation: A computational fluid dynamics analysis","volume":"76","author":"Zhu","year":"2012","journal-title":"Int. J. Pediatr. Otorhinolaryngol."},{"key":"ref_24","first-page":"15","article-title":"Stresses induced by edgewise appliances in the periodontal ligament\u2014A finite element study","volume":"62","author":"McGuinness","year":"1992","journal-title":"Angle Orthod."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"995","DOI":"10.1016\/S0142-9612(97)00021-5","article-title":"Elastic modulus of the periodontal ligament","volume":"18","author":"Rees","year":"1997","journal-title":"Biomaterials"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"531","DOI":"10.1093\/ejo\/cjs063","article-title":"Stress distribution and displacement by different bone-borne palatal expanders with micro-implants: A three-dimensional finite-element analysis","volume":"36","author":"Lee","year":"2014","journal-title":"Eur. J. Orthod."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"638","DOI":"10.1016\/j.ajodo.2013.12.029","article-title":"Effect of bone-borne rapid maxillary expanders with and without surgical assistance on the craniofacial structures using finite element analysis","volume":"145","author":"Lee","year":"2014","journal-title":"Am. J. Orthod. Dentofac. Orthop."},{"key":"ref_28","first-page":"364","article-title":"A comparative study on mechanical properties of some thermoplastic and thermoset resins used for orthodontic appliances","volume":"52","author":"Vaida","year":"2015","journal-title":"Mater. Plast."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"490","DOI":"10.1016\/j.jmps.2017.11.014","article-title":"Mechanical model of suture joints with fibrous connective layer","volume":"111","author":"Miroshnichenko","year":"2018","journal-title":"J. Mech. Phys. Solids"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1016\/j.addr.2008.09.012","article-title":"Micro- and macrorheology of mucus","volume":"61","author":"Lai","year":"2009","journal-title":"Adv. Drug Deliv. Rev."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1011","DOI":"10.1016\/S0140-6736(10)62226-X","article-title":"Normal ranges of heart rate and respiratory rate in children: A systematic review","volume":"377","author":"Fleming","year":"2011","journal-title":"Lancet"}],"container-title":["Biomimetics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2313-7673\/11\/1\/5\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T14:35:07Z","timestamp":1766500507000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2313-7673\/11\/1\/5"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,23]]},"references-count":31,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["biomimetics11010005"],"URL":"https:\/\/doi.org\/10.3390\/biomimetics11010005","relation":{},"ISSN":["2313-7673"],"issn-type":[{"value":"2313-7673","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,23]]}}}