Most of the literature regarding osseointegrated implantation for hearing rehabilitation focuses on the 5.5 mm abutment. This study aimed to add to the data available on the survival of the 8.5 mm abutment, and to describe its utility in obese patients.

To review the outcomes of patients who received a bone-anchored hearing aid implant, and create a model comparing the mechanical forces acting upon combinations of fixture and abutment lengths.

Retrospective chart review and mathematical modelling.

In this retrospective cohort study comprising 25 patients, less abutment overgrowth was observed in the 8.5 mm abutment recipients versus recipients of the 5.5 mm abutment. When the principle of equilibrium of a rigid body was applied, the 8.5 mm abutment was at a calculated mechanical disadvantage compared with the 5.5 mm abutment.

The 8.5 mm abutment may be useful in patients with copious subcutaneous soft tissue as in the obese population. The 8.5 mm abutment has a calculated mechanical disadvantage, potentially putting the implant under greater mechanical stress; however, the clinical relevance of this is unclear.