Effects of 1% Micro-silicone Dioxide Filler on Soft Liner Mechanical Properties

Objectives: Denture lining material has a key role in modern prosthodontics due to restoring health of inflamed and distorted mucosa. The soft lining ability to resist plastic deformation under load is of practical importance. Therefore, this study aims to investigate the effect of micro-silicone dioxide filler on the surface hardness and transverse strength of soft denture liner material.
Methods: Samples (n=10) were prepared for surface hardness test according to ANSI/ADA Specification (No.12); and transverse strength test ADA (No.57&12). Specimens prepared using old denture mould technique. The respectable thickness of old hard resin denture was 2mm, while the relining layer was 1mm in thickness (Vertex-Germany). 1% micro-silicone dioxide particles (USA) of 0.01-0.04µm by weight were added to the reline powder and settled homogenously by mixing together for 1min. Then, the special liquid added according to the manufacturer and mix for 30sec. The curing process was carried out using water-bath technique starting at room temperature to set up at 70˚C for 90min, and then at 100˚C for 30min. Sample left to cool at room temperature, finished, polished and stored in distilled water (48h). Surface hardness specimens tested using (Shore A, Italy) tester device with indenter cone diameter of 0.79mm. While the transverse specimens tested using Universal Instron machine (Germany) with cross-head speed of 1mm/min.
Results: There was statistical significant difference in the mechanical properties of the soft denture liner with micro-silicone dioxide particles (P<0.05). Denture soft liner with 1% micro-silicone dioxide particles had surface hardness of 79(±2) Shore A, while that liner without filler had 64(±1) Shore A. The transverse strength of lining resin has been improved from 43(±5)N/mm² without filler to 75(±3)N/mm² with 1% micro-silicone dioxide particles.
Conclusions: 1% of micro-silicone dioxide particles as reline filler could improve the mechanical properties of soft denture liner material giving a promise to superior resist to plastic deformation under load.