Zygomatic Implants Land About 2 mm Off Plan, New Study Finds

Zygomatic implants landed 1.92 mm from their planned entry point, per a November 3, 2026 study. The apex was missed by 1.73 mm. Researchers placed 48 implants in 24 patients with severe upper jaw atrophy and compared each with its CBCT plan.

TL;DR

• Surgeons in Egypt placed 48 zygomatic implants in 24 patients with a partially guided template.

• Implants missed the plan by 1.92 mm at the head and 1.73 mm at the apex.

• The study measured short-term accuracy only, with no freehand or navigated comparison.

What Did The New Zygomatic Implant Study Investigate?

The study asked how closely a zygomatic implant ends up where the computer plan put it.

Zygomatic implants are extra-long fixtures anchored in the cheekbone, here 37.5 to 47.5 mm. All 24 patients had 4 mm or less of posterior maxillary bone. Each received two zygomatic and four anterior standard implants under general anesthesia. A fixed provisional bridge followed within 24 hours.

The surgeon planned every case in Blue Sky Plan software, following the Zygoma Anatomy-Guided Approach (ZAGA). The broader digital workflow behind this kind of surgery is covered in our guide to guided implantology.

How Did Researchers Compare Planned And Actual Implant Positions?

The method shapes how the numbers should be read.

1. A preoperative CBCT scan fed the virtual plan.

2. A 3D-printed, mucosa-supported guide with metal sleeves directed the drills.

3. The surgeon removed the guide and inserted each implant by hand.

4. A second CBCT scan was taken two weeks after surgery.

5. Mimics and 3-matic software overlaid the new scan on the plan.

6. Three blinded examiners measured the offset at the implant head and apex.

Guided drilling with freehand insertion makes this a partially guided protocol. Deviation was a straight-line distance in a horizontal plane, and no angular deviation was reported. The scans came from a Planmeca Viso G7, covered in this Viso G7 review.

How Accurate Were The Digitally Planned Zygomatic Implants?

Every implant missed its plan by a measurable amount, and the miss was consistent.

Coronal Deviation Averaged 1.92 mm

Coronal deviation is the offset at the implant entry point, where the prosthetic platform sits. No implant came within 1.46 mm of its planned entry. The authors describe a systematic shift of about 2 mm.

A consistent miss points to a fixed error source more than a shaky hand. A guide resting on soft, atrophic mucosa can settle slightly off its planned seat. One candidate was excluded because a flabby ridge could not support the guide.

Apical Deviation Averaged 1.73 mm

Apical deviation is the offset at the implant tip inside the zygoma. The apex sits near the orbit and infraorbital nerve. Its spread was wider, from 0.45 to 2.68 mm. No patient had nerve disturbance, orbital injury, or an oroantral opening at three months.

What Do These Measurements Mean Clinically?

These are averages, and a single patient can sit at the top of the range. The study does not define 2 mm as a safe limit. Angled multi-unit abutments can often absorb a 2 mm head shift. The apex has less forgiveness, since the margin to the orbit varies by patient.

Spread differed between sides, but the study did not test side as a factor.

Why Does Placement Accuracy Matter For Zygomatic Implants?

A standard implant is about 10 mm long. A zygomatic implant runs four times that distance to the cheekbone. Small angle errors at the entry grow along that path.

Accuracy also shapes the prosthesis. Here, a full-arch bridge went on within a day. An entry point 2 mm off can shift the screw channel the lab must work around.

How much guidance helps is still unsettled. The 2026 Global Consensus report reached no consensus (70.9%) that guided zygomatic surgery beats freehand. A 2026 randomized trial compared fully and partially guided templates. A 2026 template-guided case series reported deviations below 2 mm and 2°. Robotic systems are covered in our dental robotics article.

What Are The Study's Limitations?

Several limits shape how far these numbers travel.

• No freehand, fully guided, or navigated comparison group

• Only 24 patients, so the 48 implants are not independent cases

• One highly experienced surgeon performed every case

• Two-week accuracy scans and three-month clinical follow-up only

• No link tested between deviation and complications or survival

• Registration and landmark errors were not measured separately

• Retrospective trial registration, as the authors report

The registration dates also need clarification. The abstract gives March 31, 2023, before recruitment began in May 2023. The paper still calls it retrospective. This is an Article in Press, so the final version may change.

What Does This Mean For Implant Surgeons?

The study gives a realistic benchmark for a partially guided, mucosa-supported workflow. Safety margins near the orbit should allow for about 2 mm of transfer error, sometimes more.

The consistent coronal shift is the most useful clue. A fixed error can be reduced with firmer guide fixation or guidance through insertion. Teams can audit their own cases by overlaying postoperative scans on the plan. Record the guide type and any changes in the dental treatment plan. Broader CBCT workflows appear in our dental implant treatment planning guide.

Robotic guidance is reaching other complex maxillary work, such as pterygoid implant placement. That is a separate development this study does not address.

Bottom Line

This study adds clinical data on how precisely virtual plans transfer to zygomatic surgery. With a partially guided template, implants landed about 1.9 mm off at the head and 1.7 mm at the apex. No serious complications appeared within three months. The study did not compare guidance methods or track long-term outcomes. Comparative trials are still needed.