Introduction:

Implant displacement into the maxillary sinus is a rare but challenging complication that can occur during second-stage surgery.

This case demonstrates the use of a bony press-fit closure technique to preserve the crestal portion of the implant site, facilitating future sinus graft re-entry and simultaneous implant placement.

Method:

45‑year‑old healthy, non‑smoking male

Reason for Consultation: Implant rehabilitation in the posterior maxilla.

At 6‑Month Re‑entry: Implant found to be unstable during second‑stage surgery.

Implant became fully mobile and was inadvertently displaced into the maxillary sinus during attempted removal.

Results:
The displaced implant was successfully retrieved without sinus complications.
The bony press-fit closure maintained the crestal portion of the implant site, facilitating flap elevation during re-entry and implant placement.
Re-entry for sinus graft and implant placement was uneventful.
The final implant achieved excellent primary stability.

Conclusion:
The bony press-fit (bony island) closure technique provides an effective and predictable approach for managing implant displacement into the sinus.
It preserves the crestal bone at the implant site, simplifies re-entry, and allows successful sinus grafting and implant placement.