Flexural strength and flexural modulus of fiber-reinforced, soft-liner retained implant overdenture.

PURPOSE: To compare the flexural strength and modulus of ball-soft liner­retained overdentures vs ballsocket­ retained overdentures, as well as to evaluate the effect of using glass fiber reinforcement on the mechanical properties of ball-soft liner­retained overdentures. MATERIALS AND METHODS: A total of 80 overdenture specimens were fabricated and divided equally into four groups (n = 20/group): specimens with a metal matrix (group 1); a silicone soft liner matrix (group 2); reinforced with one bundle of unidirectional Stick glass fiber placed above the silicone soft liner matrix (group 3); and reinforced with four weaves of bidirectional Stick Net glass fibers 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 three-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 of group 1 only (P < .001) and not the other three groups (P >.05). CONCLUSION: Overdentures retained with a metal matrix were not significantly different from those retained with a silicone soft liner matrix in terms of flexural strength and modulus after 30 days of water storage. Placing unidirectional and bidirectional glass-fiber reinforcement above soft liner matrices can increase the flexural strength of ball-soft liner­retained overdentures.