Study of the surface hardness and modulus of elasticity of conventional and microwave-cured acrylic resins

Abstract

The aim of this study was to evaluate the following acrylic resins: Clássico, QC-20 and Lucitone, recommended specifically for thermal polymerization, and Acron MC and VIPI-WAVE, made for polymerization by microwave energy. The resins were evaluated regarding their surface nanohardness and modulus of elasticity, while varying the polymerization time recommended by the manufacturer. They were also compared as to the presence of water absorbed by the samples. The technique used was nanoindentation, using the Nano Indenter XP, MTS. According to an intra-group analysis, when using the polymerization time recommended by the manufacturer, a variation of 0.14 to 0.23 GPa for nanohardness and 2.61 to 3.73 GPa for modulus of elasticity was observed for the thermally polymerized resins. The variation for the resins made for polymerization by microwave energy was 0.15 to 0.22 GPa for nanohardness and 2.94 to 3.73 GPa for modulus of elasticity. The conclusion was that the Classico resin presented higher nanohardness and higher modulus of elasticity values when compared to those of the same group, while Acron MC presented the highest values for the same characteristics when compared to those of the same group. The water absorption evaluation showed that all the thermal polymerization resins, except for Lucitone, presented significant nanohardness differences when submitted to dehydration or rehydration, while only Acron MC presented no significant differences when submitted to a double polymerization time. Regarding the modulus of elasticity, it was observed that all the tested materials and products, except for Lucitone, showed a significant increase in modulus of elasticity when submitted to a lack of hydration.

Thermoplastic acrylic resin with self‐healing properties

“…The results of reduced elastic modulus and hardness of the virgin and healed surfaces are presented in Table , and they are in accordance with literature data . The reduced modulus and hardness for the healed surface was about 79% and 75% in comparison to the virgin surface, respectively.…”

Effect of repeated disinfections by microwave energy on the physical and mechanical properties of denture base acrylic resins

“…Although classic finding has shown that hardness is not influenced by the acrylic resin type (15), in the present study, Onda-Cryl presented higher hardness, QC-20 presented lower hardness, and Clássico had intermediary Knoop hardness values in the non-disinfected condition ( Table 1). In the same way as observed in a previous study, different results of surface nanohardness were obtained when different commercial types of denture base acrylic resins were evaluated (16).…”

Micro-hardness of Acrylic Resin utilized for Provisional Crowns: Effect of different polymerization techniques and pH-Cycling

“…The option for one of these techniques is based on factors like the type or the extension of the prosthesis and the expected treatment longevity. The polymerization technique can modify the acrylic resin properties [8,9]. It may compromise the quality of the provisional crowns and can contribute to the treatment failure [1,3,10].…”