Long-term Stability, Survival, and Tolerability of a Novel Osseointegrated Implant for Bone Conduction Hearing: 3-year Data from a Multicenter, Randomized, Controlled, Clinical Investigation

Objective: To compare the 3-year stability, survival, and tolerability of 2 osseointegrated implants for bone conduction hearing: a wide 4.5-mm-diameter moderately roughened implant with a rounded 6-mm abutment (test) and a 3.75-mm diameter as-machined implant with a conically shaped 5.5-mm abutment (control).

Study Design: In this randomized, prospective, controlled, multicenter clinical study, 77 adult patients were included. Test and control implants were randomly assigned in proportions of 2:1. The implants were loaded with the sound processor from 6 weeks postimplantation. Follow-up after surgery was conducted at 10 days; at 4, 6, 8, and 12 weeks; and at 6, 12, 24, and 36 months after surgery. At every visit, implant stability quotient (ISQ) values were recorded by means of resonance frequency analysis (RFA), and skin reactions were evaluated according to Holgers' classification.

Results: Statistically significantly higher mean ISQ values were recorded for the test implant compared with the control implant at each evaluation time point. Between 2 and 3 years after surgery, ISQ values decreased but remained above baseline values. Implant survival was high for both implants: 96.2% of the test implants and 100% of the control implants survived these 3 years. Statistically significantly improved soft tissue outcomes were observed in the test implant group.

Conclusion: This extensive long-term clinical investigation demonstrated that the test implant is more stable in terms of ISQ-values and provides high tolerability for the soft tissue. The results show that implant loading at 6 weeks is safe.