title: Shape Optimization for Additive Manufacturing of Removable Partial Dentures--A New Paradigm for Prosthetic CAD/CAM.
abstract: With ever-growing aging population and demand for denture treatments, pressure-induced mucosa lesion and residual ridge resorption remain main sources of clinical complications. Conventional denture design and fabrication are challenged for its labor and experience intensity, urgently necessitating an automatic procedure. This study aims to develop a fully automatic procedure enabling shape optimization and additive manufacturing of removable partial dentures (RPD), to maximize the uniformity of contact pressure distribution on the mucosa, thereby reducing associated clinical complications. A 3D heterogeneous finite element (FE) model was constructed from CT scan, and the critical tissue of mucosa was modeled as a hyperelastic material from in vivo clinical data. A contact shape optimization algorithm was developed based on the bi-directional evolutionary structural optimization (BESO) technique. Both initial and optimized dentures were prototyped by 3D printing technology and evaluated with in vitro tests. Through the optimization, the peak contact pressure was reduced by 70%, and the uniformity was improved by 63%. In vitro tests verified the effectiveness of this procedure, and the hydrostatic pressure induced in the mucosa is well below clinical pressure-pain thresholds (PPT), potentially lessening risk of residual ridge resorption. This proposed computational optimization and additive fabrication procedure provides a novel method for fast denture design and adjustment at low cost, with quantitative guidelines and computer aided design and manufacturing (CAD/CAM) for a specific patient. The integration of digitalized modeling, computational optimization, and free-form fabrication enables more efficient clinical adaptation. The customized optimal denture design is expected to minimize pain/discomfort and potentially reduce long-term residual ridge resorption.
authors.affiliation: School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Junning
authors.initials: J
authors.lastname: Chen
authors.affiliation: Unit of Prosthodontics, Faculty of Dentistry, Shah Alam & Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA, Bandar Puncak Alam, Selangor, 42300, Malaysia.
authors.forename: Rohana
authors.initials: R
authors.lastname: Ahmad
authors.affiliation: Division of Preventive Dentistry, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan.
authors.forename: Hanako
authors.initials: H
authors.lastname: Suenaga
authors.affiliation: School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Sasaki
authors.affiliation: Faculty of Dentistry, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Swain
authors.affiliation: School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
mesh_terms: D017076:Computer-Aided Design; D003779:Denture Design; D003832:Denture, Partial, Removable; D006801:Humans; D008334:Mandible / Q000473:pathology; D008422:Materials Testing; D008958:Models, Molecular; D011312:Pressure