Conventional bridge framework of gold alloys are expensive. After in vitro investigations, materials were selected for preparing bridges from carbon/graphite reinforced poly(methyl methacrylate) on titanium implants. Fracture stress and flexural modulus were higher for the reinforced than for the unreinforced poly(methyl methacrylate) material. Absorption of water decreased the flexural properties of the materials.

Reference
Development of carbon/graphite fiber reinforced poly (methyl methacrylate) suitable for implant-fixed dental bridges.
Ruyter IE, Ekstrand K, Bjork N.
Dent Mater. 1986 Feb; 2(1): 6-9.