Indications for Zygomatic Implants

Consensus statement 1: Zygomatic implants are indicated in cases with maxillary bone atrophy or deficiency (118 patients), unsuccessful previous treatments with grafts and/or implants (34 patients), avoidance of staged bone graft procedures (29 patients) and conditions that may complicate traditional bone grafting procedures, such as benign cysts and trauma (5 patients). This statement is supported by 10 publications reporting on 209 patients and 622 implants.

Consensus statement 2: Zygomatic implants are an alternative when the maxillary bone is completely or partially absent, secondary to resection, trauma, or congenital defects. This statement has a moderate level of evidence, it is supported by 3 papers (23 patients) reporting on the use of zygomatic implants in these situations.

Consensus statement 3: Zygomatic implants are an alternative when the maxillary bone is completely or partially absent, secondary to failure of previously placed implants and/or bone grafts. This statement is supported by six articles reporting on 34 patients utilized as a rescue alternative in cases of failure of bone grafts and previous implants, and expert opinion.

Consensus statement 5: Zygomatic implants are an evidence-based alternative to support fixed or removable prostheses to restore partially or completely edentulous maxillae, allowing high survival rates when splinted to other implants. This statement is based on data collected from the papers included in this review, that showed a mean survival rate of 97% (89–100%) in a mean follow-up period of 28.5 months (range 12–162 months).

Consensus statement 7: The quad zygomatic implant approach (two zygomatic implants bilaterally placed) can be indicated as an alternative when conventional implants cannot be placed in the posterior and anterior maxillary regions, and grafting alternatives are not feasible, predictable, or preferred by patients. In this situation all implants should be splinted. This statement is supported by 7 publications reporting on 107 patients with quad zygoma approach.

1) Who should perform zygomatic implant treatment?

Zygomatic implants are considered a complex treatment. The success of the treatment is highly dependent on the clinician skill and experience. There is a need for surgical and restorative expertise to address all potential difficulties and complications.

2) Who is a candidate for zygomatic implants?

Zygomatic implants are an evidence-based alternative to support fixed or removable prostheses to restore partially or completely edentulous maxillae, allowing high survival rates when splinted to other implants. Zygomatic implants are an alternative when the maxillary bone is completely or partially absent, secondary to resection, trauma or congenital defects. Zygomatic implants are an alternative when the maxillary bone is completely or partially absent, secondary to failure of previously placed implants and/or bone grafts.

3) What diagnostic tools are recommended to assess the surgical field?

A CT/CBCT including the mid-face, allowing for 3D assessment of the maxillary and zygomatic bone volume and sinus health should be obtained. Preoperative evaluation for a lack of existing sinus pathologies is recommended. The use of specific software for planning, including the image of the planned prostheses and 3D anatomic models is an option.

4) What is the degree of maxillary atrophy to consider zygomatic implants?

Objective criteria should be utilized to determine the amount of bone atrophy. A 3D assessment of the maxillary and zygomatic bone volume is recommended. The most cited anatomical classification is Cawood and Howell (1988), with class IV, V and VI. Each site should be individually analyzed, and treatment options should be discussed with the patients, considering the risks, benefits, the final prosthetic outcome, total treatment time, long-term outcomes and patients preference and conditions.

5) Can I consider zygomatic implants for maxillofacial defects?

Zygomatic implants in maxillofacial rehabilitation cases have additional complexity and considerations. Factors such as surveillance of malignant disease, radiation, bone and soft tissues quality and quantity, patient compliance should be considered.

6) Can I place zygomatic implants at the same time as dental extractions?

Factors such as presence of infection, hard and soft tissue quality and quantity, clinician experience and patient preference should be considered. Risks may be increased when performing zygomatic implants at the same time as tooth extractions.

What is the role of guided surgery or dynamic navigation for insertion of zygomatic implants?

Direct visualization of the surgical field is paramount to avoid disorientation and anatomical complications (f.e. to the orbital cavity or the infra-temporal fossa).

7) Should the sinus membrane be elevated (“preserved”) for insertion of zygomatic implants?

Neither the literature nor expert consensus on preserving the sinus membrane for ZI placement exists.

9) When zygomatic implants are used, what type of prosthesis can be utilized?

Once generally accepted restorative concepts for implant-supported-prosthesis are followed, removable or fixed restorations can be considered, provided that all implants are splinted. Factors to be considered include prosthetic material, esthetic factors (e.g., lip support, smile line), condition of the opposing dentition, available space for the prosthesis, planned implant distribution, presence and length of cantilever, space available for hygiene and maintenance, proper abutment selection and timing of implant platform position, patient preference and compliance.