Abstract
ObjectivesTo examine the retention force of removable dental prosthesis (RDP) clasps made from polyetheretherketone (PEEK) and cobalt-chrome-molybdenum (CoCrMo, control group) after storage in water and artificial aging.Materials and methodsFor each material, 15 Bonwill clasps with retentive buccal and reciprocal lingual arms situated between the second pre- and first molar were manufactured by milling (Dentokeep [PEEKmilled1], NT digital implant technology; breCAM BioHPP Blank [PEEKmilled2], bredent), pressing (BioHPP Granulat for 2 press [PEEKpressed], bredent), or casting (remanium GM 800+ [CoCrMo], Dentaurum); N = 60, n = 15/subgroup. A total of 50 retention force measurements were performed for each specimen per aging level (initial; after storage [30 days, 37 °C] and 10,000 thermal cycles; after storage [60 days, 37 °C] and 20,000 thermal cycles) in a pull-off test. Data were statistically analyzed using one-way ANOVA, post hoc Scheffé and mixed models (p < 0.05).ResultsInitial, PEEKpressed (80.2 ± 35.2) and PEEKmilled1 (98.9 ± 40.3) presented the lowest results, while PEEKmilled2 (170.2 ± 51.8) showed the highest values. After artificial aging, the highest retention force was observed for the control group (131.4 ± 56.8). The influence of artificial aging was significantly higher for PEEK-based materials. While PEEKmilled2 and PEEKpressed showed an initial decline in retention force, all other groups presented no impact or an increase in retention force over a repetitive insertion and removal of the clasps.ConclusionsWithin the tested PEEK materials, PEEKmilled2 presented superior results than PEEKpressed. Although CoCrMo showed higher values after artificial aging, all materials exhibited sufficient retention to recommend usage under clinical conditions.Clinical relevanceAs RDPs are still employed for a wide range of indications, esthetic alternatives to conventional CoCrMo clasps are sought.
Highlights
Felicitas Mayinger and Danka Micovic contributed to this work.Removable dental prostheses (RDPs) are commonly used to treat patients with large or multiple edentulous areas
Patients have specified a metallic taste in connection with a new removable prosthesis manufactured of CoCrMo or shown allergic reactions of the oral mucosa [9,10,11], These disadvantages called for the implementation of new dental compositions such as high-performance thermoplastic polymers as clasp materials in the treatment with RDPs
To reduce extensive surgical procedures for fixed dental prostheses (FDPs) treatment of patients presenting with deficiencies of soft and hard tissues in the esthetic zone and enable RDPs to be manufactured solely from PEEK, a pale-pink shade option has been developed to imitate the color of the gum
Summary
Felicitas Mayinger and Danka Micovic contributed to this work.Removable dental prostheses (RDPs) are commonly used to treat patients with large or multiple edentulous areas. Non-precious metals like CoCrMo can cause galvanic corrosions as metallic ions solved in saliva interact with amalgam or gold restorations [12] In this context, patients have specified a metallic taste in connection with a new removable prosthesis manufactured of CoCrMo or shown allergic reactions of the oral mucosa [9,10,11], These disadvantages called for the implementation of new dental compositions such as high-performance thermoplastic polymers as clasp materials in the treatment with RDPs. Polyetheretherketone (PEEK), a member of the polyaryletherketone (PAEK) family, possesses a high biocompatibility, excellent mechanical characteristics, a high chemical stability, and a high temperature resistance [13,14,15,16]. The use of CAD/CAM allows for a fully digital workflow that entails numerous advantages like an increased material homogeneity and the ability to reproduce restorations, for example, when elderly patients misplace their prostheses
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