Long-term Treatment Outcomes with Zygomatic Implants

Consensus statement 6: The mean zygomatic implant survival was 96.2% [95% CI 93.8; 97.7] over a mean follow-up of 75.4 months (6.3 years) with a follow-up range of 36–141.6 months (3–11.8 years). This statement is based on a meta-analysis of 18 case series reports, which included a total of 1349 ZIs placed in 623 patients.

Consensus statement 8: ZI survival for immediate Loading protocols were 98.1% [95% CI 96.2; 99.0] over a mean of 73.6 months follow-up. This statement is based on a meta-analysis of 7 case series reports, which included 458 ZIs.

Consensus statement 9: Mean survival prevalence for delayed load protocols was 95% [95% CI 91.7; 97.1] over a mean of 69.3 months follow-up. This statement is based on a meta-analysis of 7 case series reports, which included 535 ZIs.

Consensus statement 12: A higher failure incidence may occur within the first year (2%) compared to that of subsequent years (0.5%/year). This statement is based on a meta-analysis of 17 case series reports, which included a total of 1247 ZIs.

Consensus statement 13: The overall annual failure incidence of ZIs was 0.7%, with follow-up times ranging from 36 to 141.6 months. This statement is based on a meta-analysis of 18 case series reports, which included a total of 1349 ZIs placed in 623 patients.

Consensus statement 14: Reasons for failure within the first year were related to a failure to integrate or subsequent loss of integration/stability. Failure within the subsequent years was related to loss caused by biological or mechanical complications. This statement is based on a meta-analysis of 18 case series reports, which included a total of 1349 ZIs placed in 623 patients.

Consensus statement 15: Sinusitis is the most commonly reported biological complication related to ZI therapy. Sinusitis is reported to be the most common complication which may lead to ZI implant loss. There is no clear relationship between sinusitis and ZI survival. Sinusitis presented with a total prevalence of 14.2% [95% CI 8.8; 22.0] over a mean of 65.4 months follow- up. The prevalence of sinusitis ranged from 2.8% [95% CI 0.1; 14.5] to 36.4% [95% CI 20.4; 54.9] from 36 to 141.6 months of mean follow-up. Disease was diagnosed clinically, radiographically, using patient-reported questionnaires, or via combined methods. This statement is based on descriptive data from 11 case series reports in 409 patients.

Consensus statement 17: Sinusitis may be successfully treated. When sinusitis was diagnosed, successful treatment with antibiotics and/or via a surgical meatotomy was reported with no further consequences. This statement is based on descriptive data from 7 case series reports in 22 patients.

Consensus statement 18: 10 of 18 studies reported factors related to the biological complications of ZI therapy. Among them, one study, investigating two groups of 10 patients (20 in total), reported a prevalence of peri-implant ZI mucositis at 13.1% (3.7–41%) within an atrophic group and 39.7% (9.7–91.7%) in an oncologic group over a group mean follow-up of 39.9 months (± 19.5). One study reported recession exposing 2–3 threads in 14% of ZI implants (n = 6 of 43) in 25 patients over 72 months of mean follow-up (48–72). One study reported infective soft tissue dehiscences affecting 6 of 67 ZI (9%) in 33 patients with a mean follow-up of 141.6 months (range 109–198).

Consensus statement 19: Technical complications for ZI supported reconstructions include fracture of the metal substructure, chipping or loss of the veneering material (ceramic or acrylic), and abutment or screw fracture and/or loosening. 3 metal framework fractures occurred in 43 prostheses. 77 episodes of veneering acrylic loss occurred in 228 prostheses. 28 episodes of veneering ceramic loss occurred in 141 prostheses. 8 episodes of prosthetic tooth loss occurred in 116 prostheses. 29 episodes of screw or abutment loosening occurred in 323 prostheses. 15 episodes of screw or abutment fracture occurred in 136 prostheses. This statement is based on descriptive data from 10 case series reports including 400 prostheses with a mean follow-up ranging from 36 to 120 months.

Consensus statement 20: The mean prosthesis survival supported by ZIs was 94% [95% CI 88.6; 96.9] at 76.0 months of mean follow-up. Prostheses constituted fixed and removable designs, with materials including resin and ceramic superstructures on metal substructures. This statement is based on a meta-analysis of 9 case series reports, which included 304 ZI supported prostheses.

Consensus statement 21: Patients reported an increase in satisfaction using a range of patient-reported outcome measures (PROMs) when rehabilitated with ZI supported reconstructions. This statement is based on descriptive data from 7 case series reports in 266 patients using OHIP14, OHIP EDENT, Likert, and subjective questioning assessment tools.

8) Do specific loading protocols have an influence on the long‑term outcomes of zygomatic implant therapy?

ZI survival rates appear to be slightly higher for immediate over delayed loading protocols subject to adequate primary implant stability. Immediate loading also confers benefits to the patient through immediate functional rehabilitation. However, delayed loading techniques are also clinically acceptable.

10) What are the long‑term therapeutic advantages of zygomatic implants?

Current survival data support the use of zygomatic implants as a long-term therapeutic option. ZIs present an opportunity to rehabilitate patients who lack either the desire to undergo extensive augmentation procedures, or lack the anatomical structures required to deliver conventional implant therapy in the maxilla. ZIs may confer treatment time benefits to patients due to the possibility of immediacy in reconstruction.

11) How does zygomatic implant survival perform long‑term when compared to conventional implants?

Survival of ZIs appear to be comparable to conventional implants when used for reconstruction of the atrophic maxilla. This includes techniques such as short implants, tilted implants, and implants placed in grafted sinuses. With this in mind, ZIs may be considered as an option to support maxillary reconstructions.

12) What is the long‑term performance of zygomatic implant‑supported reconstructions?

Within the context of long-term data survival analyses, ZI reconstructions are comparable to, and have similar survival characteristics to reconstructions supported by conventional implants. They are subject to similar mechanical complications. Although no additional technical considerations are required, ZI reconstruction should be considered as a complex procedure.

13) What are the long‑term mechanical complications associated with zygomatic implants?

The most common mechanical complications include ZI prosthesis abutment or screw fracture, abutment or screw loosening, and chipping or loss of the veneering acrylic or ceramic materials. These complications may occur whether the ZI reconstructions are splinted to conventional implants or supported by ZIs alone, through a Quad Zygomatic implant approach. ZI fracture or reconstruction framework fracture have been reported as rare complications. In light of these findings, conventional prosthetic techniques to mitigate such factors are recommended.

14) What are the long‑term biological risks associated with zygomatic implants?

The most reported long-term biological complication was sinusitis. This may be successfully treated through antibiotic and/or surgical interventions. If these therapies are unsuccessful, the ZI may be lost. Oro-antral communications, peri-implant infection of the soft tissues, peri-implant mucositis, bleeding on probing and increased probing pocket depths have also been reported. Patient education in oral hygiene maintenance is paramount.

15) How should sinus infections in relation to zygomatic implants be treated?

Sinus infections are generally treated with antibiotics with a satisfactory resolution. In the absence of resolution, refractory maxillary sinus infections may need exploration of the patency of the osteo-meatal complex and other paranasal sinuses.

16) Do patients perceive a long‑term benefit from the zygomatic implant treatment experience?

Most patients report an increase in oral health-related quality of life and satisfaction with the treatment outcome.

17) Are unique challenges faced by patients receiving zygomatic implants and their reconstructions?

Zygomatic implants and their reconstructions may require a higher level of professional maintenance. There are also limitations on the range of acceptable masticatory loads. Patients’ expectations need to be managed in line with the biological and technical complexities faced by zygomatic implant therapies.