TY - JOUR ID - TI - Effects of Novel Polyetheretherketone (PEEK) Clasp Design on Retentive Force at Different Tooth Undercuts AU - Saja A. Muhsin AU - Duncan J. Wood AU - Anthony Johnson AU - NunoSereno AU - 2Paul V. Hatton PY - 2018 VL - 5 IS - 2 SP - 13 EP - 25 JO - Journal of Oral and Dental Research مجلة طب الفم والاسنان SN - 23106417 AB - Background The material characteristics of many thermoplastic materials, including PEEK, have been evaluated in vitro to investigate their mechanical and physical properties. However, all the manufacturers of thermoplastic materials and laboratories making non-metal clasp dentures still recommend the original denture design. Objectives To investigate the retentive force of a novel clasp design for PEEK thermoplastic material at 3 different undercut depths with fatigue cycling equivalent to 3 years of insertion/removal use. Materials and Methods Samples (n=10) were prepared for the test. A novel clasp designs for PEEK and conventional design for Co-Cr were created using 3D-RPD software (DWOS). PEEK-Juvora™ clasps were fabricated using a Roland 3D-milling machine; PEEK-Optima®NI1 were thermo-pressed at 200˚C mold temperature using thermopress 400 injecting unit; while Co-Cr alloy was used to cast the metal clasps. Samples were tested at tooth undercut depths of 0.25, 0.50, and 0.75 mm. They were investigated for the retentive force at the initial fabrication and after 1st, 2nd, and 3rd Year respectively of fatigue simulation. This was represented by clasp insertion and removal 3 times per day using fatigue chewing simulator machine. The data was statistically analyzed using ANOVA at 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™ exhibited the highest retention at 3 different undercut depths over 3 years followed by PEEK-Optima®NI1 at 0.75, and 0.50mm (P<0.05). However, the initial retentive force required to dislodge the PEEK-Optima®NI1 clasp processed at 200 °C was statistically non-significant (p>0.05) as the Co-Cr at 0.25 mm tooth undercut depth. Conclusion Clasps made of machined PEEK-Juvora™ and thermo-pressed PEEK-Optima®NI1 at 200 ˚C mold temperatures showed the most promising retentive force with a non-fracture tendency at deeper tooth undercut. This novel PEEK clasp design may improve the clasp retention, bracing, additionally to increase its durability comparing to Co-Crclasp.

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