Purpose: To compare the flexural strength and flexural modulus of soft liner-retained overdentures to ball-and-socket-retained overdentures, as well as to evaluate the effect of using glass fiber as a reinforcement material for soft liner-retained overdentures on such mechanical properties.
Materials and methods: A total of 80 overdenture specimens were fabricated and divided equally into four groups (n = 20 each): specimens with a metal matrix (group 1); a silicone soft liner matrix (group 2); reinforced with one bundle of unidirectional glass fiber sticks placed above the silicone soft liner matrix (group 3); and reinforced with four layers of bidirectional Stick Net glass fiber weaves placed above the silicone soft liner matrix (group 4). Half of the specimens from each group were stored in water at room temperature (23°C ± 1°C) for 24 hours, while the other half were stored in water at 37°C for 30 days before being subjected to a static 3-point loading test.
Results: After 1 day of water storage, the flexural strength and flexural modulus values of groups 1, 3, and 4 were not significantly different from each other (P = .788, P = .084), but were significantly higher than group 2 (P < .05). Water storage for 30 days significantly decreased the flexural strength and modulus values of group 1 only (P < .001) and not the other three groups (P >.05).
Conclusion: After 30 days of water storage, the flexural strength and flexural modulus values of overdentures retained with a metal housing were not significantly different from those of overdentures retained with a silicone soft liner housing. Placing uni- and bidirectional glass fiber reinforcement above soft liner matrices increases the fracture resistance of a soft liner-retained overdenture.
