Complications and risk factors associated with zygomatic implants: retrospective analysis with 73 consecutive patients followed for 3.5 years

Objectives: This retrospective study analyzed zygomatic implant survival and implant success (based on ORIS criteria) in patients treated for maxilla atrophy or after reconstruction failure.
Method and materials: Implants were placed as quads (four zygomatic implants) or hybrids (zygomatic implants and conventional implants in premaxilla) in edentulous patients using various surgical approaches, evolving from the sinus slot to Chow extended sinus elevation technique with or without Bichat fat pad. The procedure was followed by immediate loading, while clinical and radiographic evaluations spanned at least 1 year after implantation. The primary outcome was the implant survival at follow-up, and the secondary outcome was the implant success, assessed as complications according to ORIS criteria: prosthetic offset, sinus status, peri-implant soft tissue health, and implant stability.
Results: A total of 73 consecutive patients, treated with 217 zygomatic implants and 76 conventional implants, were included, with mean follow-up of 3.5 years (range 1.0 to 9.8 years). Four zygomatic implants failed in three patients, including one patient with a zygomatic bone fracture. The cumulative survival rate was 98.16%. Although in two additional cases, implants lost stability, they achieved delayed osseointegration. Other complications included 21 sinus reactions (excluding the four failures) and 28 peri-implant inflammatory reactions.
Conclusion: Zygomatic implants offered a predictable treatment option for extreme maxillary jawbone atrophy with a relatively low complication rate and no severe injuries. The Chow technique with the Bichat fat pad positively impacted zygomatic implant success and survival, whereas smoking, implantation in fresh sockets, and the limited experience of the surgeon negatively affected the outcomes.