Influence of High-Pressure Polymerization on Mechanical Properties of Denture Base Resins

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.

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 (σ_f ), elastic modulus (E_f ), hardness, density (ρ), flexural deformation at maximal flexural stress, flexural load energy (U_r ) and viscoelastic properties (E', E'', Tanδ, T_g ) were analyzed using one-way ANOVA (α = 0.05), Scheffé multiple means comparisons (α = 0.05) and Weibull statistics (for σ_f ). SEM images of the fractured surfaces were obtained.

E_f , E', E'' and density of HP polymerized Probase hot were significantly higher than conventional heat polymerized Probase Hot, whereas T_g was significantly lower and σ_f , Tanδ, hardness, flexural deformation at maximal flexural stress, U_r were not significantly different. The highest values for σ_f , flexural deformation at maximal flexural stress, U_r and Weibull modulus were obtained with Ivobase CAD.

HP polymerization does not significantly increase the mechanical properties of denture base resins.