Reinforcing Pourable Cold-Cured Resin (in-Vitro) with Micro-Glass Beads

Background and Objective: Weropress is a pourable auto-polymerising acrylic resin which has recently been used in making dentures. It is characterised by high colour stability and quick setting. However, it is not as strong as heat-polymerised acrylic resin. The objective of this in-vitro study is to find out the effect of adding micro-glass beads on flexural strength, hardness and surface roughness of “Weropress”. Methods: In this study, 24 65×10×3 mm specimens were produced from Weropress following the manufacturer’s instructions (casting process). The specimens were divided into 4 groups (n=6): group 1 was “control” which had no additives, group 2; 3; and 4 contained micro-glass particles at ratios 5%, 10%, and 15%. After conventional finishing and polishing procedure, all specimens were immersed in distilled water at room temperature for 2 days. Then, the surface roughness (3 times, 4mm), hardness (four times at 50 g load for 30 sec dwell time), and 3-point bending test (5mm/min speed, 50 mm heads apart) were applied on each specimen and then evaluated. Findings: Flexural strength reduced for 97 MPa when no filler was added. When 15% filler was added, it reached 75.5 MPa, which had a significant decrease (p=0.03). Other groups showed no significant difference (79.5 MPa and 81.5 MPa). Vickers hardness was fluctuating around (16 MPa) of control following the addition of fillers; however, all testing groups were not significantly different from control. Surface roughness has increased in all groups from 0.53 µm up to 0.77 µm but with no significant difference. Conclusion: According to results, the addition of micro-glass beads on Weropress powder at 5%, 10%, and 15% has no strengthening effect on Weropress with no important effect on hardness and surface roughness.