title: Influence of thickness and undercut of thermoplastic resin clasps on retentive force.
abstract: Thermoplastic resin clasps have been used for esthetic denture rehabilitation. However, details of the design of the clasps have never been thoroughly clarified. This study investigated the retentive forces of thermoplastic resin clasps for non-metal clasp dentures. The retentive forces of all thermoplastic resin clasps depended on the elastic modulus of each resin, undercuts, thickness, and widths of the tested. A clasp with more than 0.5 mm undercut and 1.0 mm thickness is needed for Valplast. Similarly, more than 0.25 mm undercut and 1.0 mm thickness and 0.5 mm undercut and 0.5 mm thickness are required for Estheshot and Reigning, respectively; thus, the recommended clasp arm thickness is 1.0 mm to 1.5 mm for Valplast and Estheshot and 0.5 mm to 1.0 mm for Reigning when the width of the retentive arm is 5.0 mm.
authors.affiliation: Department of Removable Prosthodontics, Tsurumi University School of Dental Medicine, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama, Kanagawa 230- 8501, Japan. osada-hidekazu@tsurumi-u.ac.jp
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Osada
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Shimpo
authors.forename: Tohru
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Chikahiro
authors.initials: C
authors.lastname: Ohkubo
mesh_terms: D016734:Dental Clasps; D003779:Denture Design; D003781:Denture Retention; D003832:Denture, Partial, Removable; D055119:Elastic Modulus; D006358:Hot Temperature; D008422:Materials Testing; D009757:Nylons; D018583:Pliability; D011076:Polycarboxylate Cement; D011093:Polyethylene Terephthalates; D011108:Polymers; D012117:Resins, Synthetic; D013450:Sulfones
chemical_list: D009757:Nylons; D011076:Polycarboxylate Cement; D011093:Polyethylene Terephthalates; D011108:Polymers; D012117:Resins, Synthetic; D013450:Sulfones; C005506:polycarbonate; C045672:Reigning resin