Occult peri-implant oroantral fistulae: posterior maxillary peri-implantitis/sinusitis of zygomatic or dental implant origin. Treatment and prevention with bone morphogenetic protein-2/absorbable collagen sponge sinus grafting.

Sinus floor grafting with bone morphogenetic protein-2 for transsinus implant placement or as a salvage technique for sinus-involved peri-implantitis has been found to be successful. Transsinus implants for All-on-Four treatment, zygomatic implants including quad zygomatics, and infected transsinus implants underwent peri-implant grafting, which was found to seal off the sinus cavity from the oral cavity in an effort to prevent or treat sinusitis/peri-implantitis.