Influence of high-pressure polymerization on mechanical properties of denture base resins

Abstract
Purpose: The purpose of this study was to study the influence of high-pressure (HP) polymerization
on the mechanical properties of denture base PMMA resins compared with conventional thermopolymerization and PMMA discs for digital dentures.
Materials and Methods: Three groups of blocks were prepared: Probase Hot (Ivoclar Vivadent,
Lichtenstein) conventionally heat polymerized at 100°C, Probase Hot heat polymerized at 100°C
under HP (200 MPa) and Ivobase CAD (Ivoclar Vivadent, Lichtenstein). Samples for
mechanical/physical (n=30) and samples for viscoelastic (n=10) characterizations were cut from the
blocks. Flexural strength (Vf), elastic modulus (Ef), hardness, density (ρ), flexural deformation at
maximal flexural stress, flexural load energy (Ur) and viscoelastic properties (E’, E’’, TanG, Tg) were
analyzed using one-way ANOVA (D= 0.05), Scheffé multiple means comparisons (D=0.05) and
Weibull statistics (for σf). SEM images of the fractured surfaces were obtained.
Results: Ef, E’, E’’ and density of HP polymerized Probase hot were significantly higher than
conventional heat polymerized Probase Hot, whereas Tg was significantly lower and Vf, TanG,
hardness, flexural deformation at maximal flexural stress, Ur were not significantly different. The
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highest values for Vf, flexural deformation at maximal flexural stress, Ur and Weibull modulus were
obtained with Ivobase CAD.
Conclusion: HP polymerization does not significantly increase the mechanical properties of denture
base resins