IADR Abstract Archives
Retentive Force of Novel Polyetheretherketone (PEEK) Clasp Design
Objectives: The mechanical properties of Cobalt-Chromium (Co-Cr) enable removable partial dentures (RPDs) to be designed incorporating retentive clasps. With the advent of high performance polymer materials for RPDs which exhibit significantly different mechanical properties to that of Co-Cr, the aim of this study was to evaluate the retentive force of a novel clasp design made from PEEK thermoplastic material compared to conventional Co-Cr alloy at different undercut depths, and after being subjected to fatigue cycling simulating 3years use.
Methods: Samples (n=10) were prepared for each material. A novel clasp design for PEEK polymer and a conventional design for Co-Cr were created using CAD software system (DWOS). PEEK-Juvora™ clasps were fabricated from the design file using a milling machine (Roland-DWX-50,USA); PEEK-Optima®NI1 clasps thermo-pressed at 200°C mould temperature (Invibio Ltd.) using a Thermopress-400 injecting unit (Bredent,Germany). Co-Cr alloy was used to cast the metal clasps (Wironit-Bego,Germany). Samples were produced for 0.25, 0.50, and 0.75mm of tooth undercut. The retentive force was recorded using universal-testing machine (Lloyd-England) immediately after fabrication and subsequently following simulation of 1, 2, and 3years of use. This simulation aimed to reproduce the clasp insertion and removal 3times/day using fatigue chewing simulator machine (England). The data was statistically analyzed (ANOVA,P<0.05).
Results: There was a statistically significant difference (P<0.05) between the retentive force of the PEEK compared to Co-Cr clasps. PEEK-Juvora™ clasps exhibited the highest retention force at 3different undercuts over 3years followed by PEEK-Optima® at 0.50, and 0.75mm (P<0.05). However, the initial retentive force required to dislodge the PEEK-Optima® clasp was statistically non-significant (P>0.05) to the Co-Cr at 0.25mm and 0.75mm undercut, figure (1).
Conclusions: Clasps made of PEEK-Juvora™ and thermo-pressed PEEK-Optima®NI1 showed the most promising retentive force and fracture resistance at deeper tooth undercut. This novel PEEK clasp design may improve the clasp retention, bracing, additionally increased durability compared to Co-Cr clasps.
Methods: Samples (n=10) were prepared for each material. A novel clasp design for PEEK polymer and a conventional design for Co-Cr were created using CAD software system (DWOS). PEEK-Juvora™ clasps were fabricated from the design file using a milling machine (Roland-DWX-50,USA); PEEK-Optima®NI1 clasps thermo-pressed at 200°C mould temperature (Invibio Ltd.) using a Thermopress-400 injecting unit (Bredent,Germany). Co-Cr alloy was used to cast the metal clasps (Wironit-Bego,Germany). Samples were produced for 0.25, 0.50, and 0.75mm of tooth undercut. The retentive force was recorded using universal-testing machine (Lloyd-England) immediately after fabrication and subsequently following simulation of 1, 2, and 3years of use. This simulation aimed to reproduce the clasp insertion and removal 3times/day using fatigue chewing simulator machine (England). The data was statistically analyzed (ANOVA,P<0.05).
Results: There was a statistically significant difference (P<0.05) between the retentive force of the PEEK compared to Co-Cr clasps. PEEK-Juvora™ clasps exhibited the highest retention force at 3different undercuts over 3years followed by PEEK-Optima® at 0.50, and 0.75mm (P<0.05). However, the initial retentive force required to dislodge the PEEK-Optima® clasp was statistically non-significant (P>0.05) to the Co-Cr at 0.25mm and 0.75mm undercut, figure (1).
Conclusions: Clasps made of PEEK-Juvora™ and thermo-pressed PEEK-Optima®NI1 showed the most promising retentive force and fracture resistance at deeper tooth undercut. This novel PEEK clasp design may improve the clasp retention, bracing, additionally increased durability compared to Co-Cr clasps.
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