Overcoming challenges with navigation in edentulous maxilla

Overcoming Challenges with Navigation in the Edentulous Maxilla

Introduction

This webinar, presented by Dr. Fan Shengchi and moderated by Dr. James Chow, explores one of the most complex frontiers in implant dentistry: navigation in the fully edentulous maxilla. As edentulous cases become increasingly common with aging populations and the demand for predictable full-arch rehabilitation continues to grow, clinicians are challenged by reduced anatomical landmarks, severe bone resorption, and the need for prosthetically driven accuracy.

Through a combination of evidence, clinical protocols, and real-world cases, this session highlights how dynamic navigation and emerging robotic systems can enhance implant placement accuracy, improve patient outcomes, and reduce surgical complications. The presentation is anchored in clinical science but also provides a practical roadmap for clinicians who wish to integrate navigation into their own practice.

The Unique Challenge of the Edentulous Maxilla

The maxilla, particularly in fully edentulous patients, represents one of the most difficult surgical environments for implant placement. Unlike dentate or partially edentulous cases, there are no remaining teeth to serve as reference points for intraoral registration. Bone resorption patterns further complicate stability, with thin cortical walls and proximity to the maxillary sinus limiting available anchorage.

Traditional freehand approaches in this context often suffer from significant positional deviations, particularly in angulation, leading to biomechanical compromise, prosthetic misfit, or even sinus complications. Static guides improve precision, but they lack flexibility during surgery and can be difficult to stabilize in a resorbed ridge. This sets the stage for dynamic navigation and robotic technologies, which promise real-time control and adaptive planning even in the most compromised anatomy.

Dynamic Navigation Workflow

Dr. Fan outlined a standardized navigation workflow for edentulous maxilla cases:

1. CBCT acquisition

   A high-resolution CBCT scan provides volumetric data on residual bone, sinus morphology, and anatomical safety zones.

2. Prosthetically driven planning

   Digital wax-ups are integrated with the CBCT dataset to ensure implants are placed in harmony with the final restoration. This “prosthesis-first” mindset is essential for esthetics, occlusion, and long-term function.

3. Registration and fiducial markers

   Since teeth are absent, registration is achieved using bone-anchored fiducial markers or mini-screws placed in strategic positions. These provide a stable reference for tracking systems.

4. Calibration and instrument tracking

   The drill handpiece is calibrated against the navigation system. Reflective markers or optical trackers ensure that every movement is captured in real time.

5. Implant site preparation

   Under navigation, the surgeon can visualize the entry point, angulation, and depth relative to the prosthetic plan. Deviations are immediately visible and corrected on the spot.

6. Implant insertion

   The final implant is placed with guidance, achieving accuracy often within 1 mm at the entry point and 2–3° angulation deviation, well within clinically acceptable thresholds.

This workflow, though technically demanding, provides unparalleled adaptability compared with static guides, particularly when intraoperative changes are required.

Robotic-Assisted Navigation

A major highlight of the session was the introduction of robotic systems for implant placement. Unlike dynamic navigation, where the surgeon manually controls the drill while being guided visually, robotic platforms allow semi-autonomous or fully autonomous drilling under the surgeon’s supervision.

Robotic systems bring potential benefits:

• Stability: robotic arms eliminate micro-tremors and hand fatigue.
• Precision: deviations can be kept below 0.5 mm, even in long drilling trajectories such as zygomatic implants.
• Safety: haptic feedback and motion constraints prevent drilling outside the planned trajectory.

While robotic navigation is still in early adoption, Dr. Fan emphasized its potential to transform implant surgery into a more standardized and reproducible discipline.

Clinical Case: Posterior Maxilla

A representative case was presented involving a severely resorbed posterior maxilla. Freehand placement would have risked sinus perforation and poor primary stability. Using navigation:

• Implants were angulated palatally to maximize bone engagement.
• Autogenous grafting was minimized as the navigation system allowed safe exploitation of available native bone.
• Postoperative CBCT confirmed deviation of less than 1 mm from the planned path.

This case underlined how navigation not only improves safety but also reduces invasiveness by optimizing native bone utilization.

Zygomatic Implants

Perhaps the most demanding indication for navigation is the placement of zygomatic implants. Freehand techniques are associated with significant risk due to the complex three-dimensional anatomy of the zygoma, orbit, and sinus. Dr. Fan demonstrated how navigation provides real-time visualization of the implant trajectory, ensuring:

• Safe emergence in the prosthetic zone,
• Avoidance of orbital or infraorbital nerve injury,
• Greater predictability in double or quad zygoma protocols.

Studies cited during the session confirm that navigation reduces major complications in zygomatic implant surgery, while maintaining comparable survival rates.

Accuracy, Deviations, and Outcomes

Quantitative results were presented on accuracy:

• Entry point deviation: typically <1 mm with navigation, compared with 2–3 mm freehand.
• Apex deviation: ~1.5 mm with navigation, compared with >3 mm freehand.
• Angular deviation: 2–3°, compared with up to 10° freehand.

These improvements translate directly into prosthetic precision, reduced chairside adjustments, and improved patient satisfaction. Importantly, navigation also shortens the learning curve for less experienced surgeons, standardizing outcomes across operators.

Complications and Troubleshooting

Despite its advantages, navigation is not without challenges. Common issues discussed included:

• Tracking errors due to reflective marker obstruction or patient movement.
• Calibration drift, requiring recalibration mid-surgery.
• Loss of registration if fiducial screws loosen during drilling.

Dr. Fan provided troubleshooting tips, such as double-checking calibration with a test drill, ensuring clear line of sight for optical trackers, and securing fiducial screws with bicortical purchase. With proper workflow discipline, most issues can be corrected without compromising the procedure.

Q&A Session

In the discussion moderated by Dr. James Chow, participants raised questions regarding:

• The learning curve of navigation systems.
• Cost considerations versus static guides.
• Applicability in resource-limited settings.
• Future integration with artificial intelligence for automated planning.

The consensus was that while initial investment is significant, the long-term benefits in accuracy, reduced complications, and clinical reputation justify adoption in full-arch and complex maxillary cases.

Conclusion and Take-Home Messages

The session concluded with several key insights:

1. Navigation transforms the predictability of implant placement in the edentulous maxilla.
2. Prosthetically driven planning ensures functional and esthetic success.
3. Robotic systems are emerging as the next frontier, offering unmatched precision.
4. Clinical evidence supports significant improvements in accuracy, safety, and patient outcomes.
5. Adoption requires training, workflow discipline, and investment but yields sustainable benefits for both clinician and patient.