In vitro investigation of various attachments for overdentures on osseointegrated implants.

Primary splinting of fixtures with bar attachments has proved to be clinically effective for overdentures on osseointegrated implants in the edentulous mandible. However, in vitro investigations indicate that a more favourable force transfer to the individual fixtures can be attained by secondary splinting of four implants with conical double crowns. This observation could be confirmed in the present study by measurement of implant deflection in a model of the mandible by means of interferometric optical holography. Telescope crowns with conical interface brought about functionally more even movement characteristics of the implants compared to rigid or jointed bar attachments. Moreover, the conical double crowns always ensured a stable position of the denture in contrast to jointed attachments. These results underscore the need to test conical double crowns clinically as anchors for overdentures on osseointegrated implants.