Mechanical properties of abutments: Resin-bonded glass fiber-reinforced versus titanium

Purpose: The clinical success and longevity of endosseous implants, after their prosthetic finalization, mainly depends on mechanical factors. Excessive mechanical stress has been shown to cause initial bone loss around implants in the presence of a rigid implant-prosthetic connection. The implant abutments are manufactured with high elastic modulus materials such as titanium, steel, precious alloys, or esthetic ceramics. These materials do not absorb any type of shock from the chewing loads or ensure protection of the bone-implant interface, especially when the esthetic restorative material is ceramic rather than composite resin. Materials and Methods: The mechanical resistance to cyclical load was evaluated in a tooth-colored fiber-reinforced abutment prototype (TCFRA) and compared to that of a similarly shaped titanium abutment (TA). Eight TCFRAs and eight TAs were adhesively cemented on as many titanium implants. The swinging the two types of abutments showed during the application of sinusoidal load was also analyzed. Results: In the TA group, fracture and deformation occurred in 12.5% of samples, while debonding occurred in 62.5%. In the TCFRA group, only debonding was present, in 37.5% of samples. In comparison to the TAs, the TCFRAs exhibited greater swinging during the application of sinusoidal load. In the TA group extrusion prevailed, whereas in the TCFRA group intrusion was more frequent. Conclusion: TCFRA demonstrated a greater elasticity than did TAs to the flexural load, absorbing part of the transversal load applied on the fixture during the chewing function and thus reducing the stress on the bone-implant interface.