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Keywords:

  • denture rebasing;
  • material resistance;
  • denture bases;
  • denture liner

Background:  It has been suggested that microwave irradiation and prosthesis immersion in hot water after its polymerization may improve mechanical and viscoelastic properties of acrylic resins.

Purpose:  This study was proposed to verify the influence of microwave post-polymerization (PP) treatment over the flexural strength of thermo-polymerizing acrylic resin specimens (QC-20) relined or not with two different composition hard chairside auto-polymerizing reliners [Kooliner (K) and New Truliner (NT)].

Materials and Methods:  For this study, 50 specimens of 64 × 10 × 3.3 mm were polymerized and distributed into five groups. G1 (control) specimens without relining and PP; G2 specimens relined with K, without PP; G3 specimens relined with NT, without PP; G4 specimens relined with K, with PP (microwave irradiation with 650 W for 5 min); G5 specimens relined with NT, with PP. Tests were performed on a universal testing machine Instron 4411 with compression speed of 5 mm/min.

Results:  Specimens of K without PP did not show statistically different results (p < 0.05) when compared with control. However, when submitted to PP these specimens showed a significant increase in flexural strength. Specimens of NT showed the lowest flexural strength of all groups, with or without PP when compared with control and K groups.

Conclusion:  Microwave PP (650 W for 5 min) proved to be an effective method of improving the flexural strength of K relined prosthesis. However, it did not seem to affect NT specimens.