Full arch dental implant restorations, often called “All-on-4” or “All-on-6” procedures, represent the pinnacle of restorative dentistry, aiming to replace an entire set of teeth with a stable, beautiful, and functional prosthesis. While surgical planning is paramount, the ultimate success is judged on the final aesthetics. This is where photometry—the science of light and color measurement—plays a critical, often underestimated, role.
The Critical Challenge: Full Arch Accuracy
When it comes to full arch dental implant restorations—the gold standard for replacing an entire set of missing teeth—the ultimate measure of success isn’t just aesthetics, but precision. A slight mismatch in the position or angle of the restoration relative to the implants can lead to a passive fit failure, causing mechanical complications and even biological problems over time.
This is where the term photometry is often used, but the more specific and accurate technology revolutionizing this step is Photogrammetry (or Stereophotogrammetry). This technique has become the digital answer to the long-standing challenge of accurately capturing the 3D coordinates of multiple implants.
In multi-implant cases like All-on-4 or All-on-6, the margin for error is microscopic. Unlike single implants, where a minor discrepancy can sometimes be forgiven, an inaccurate impression of multiple implants creates a rigid metal or zirconia framework that doesn’t seat perfectly (non-passive fit).
A non-passive fit introduces stress at the implant-abutment interface. This stress can lead to:
Screw loosening or fracture
Prosthesis fracture
Bone loss around the implants
Traditionally, clinicians relied on highly technique-sensitive conventional impressions with splinted copings or time-consuming verification jigs—methods prone to error from material shrinkage, polymerization, or human handling.
Enter Photogrammetry: The Digital Surveyor
Photogrammetry is the science of obtaining reliable information about physical objects and the environment through the process of recording, measuring, and interpreting photographic images.
In full arch implant dentistry, specialized photogrammetry systems (like PIC and iCam4D) use a multi-camera setup to digitally “survey” the implant positions with micrometer-level accuracy.
How it Works in full arch dental implants:
Coded Scan Bodies: Unique, coded markers (scan bodies) are attached to the multi-unit abutments on each implant.
Image Capture: The photogrammetry device is held extraorally and takes a rapid burst of multiple, overlapping, high-resolution photographs from various angles.
Triangulation: Specialized software uses the camera geometry and the known spatial coordinates of the coded markers to triangulate the precise 3D position and angulation of all implants simultaneously.
Digital File Creation: The output is a highly accurate digital file (STL or PICfile) that acts as a rigid, coordinate map of the entire arch, which is then sent directly to the dental lab for prosthesis fabrication.
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Streamlining the Full Digital Workflow in full arch dental implants
Photogrammetry’s value is not just in accuracy, but in workflow efficiency.
Model-Free Potential: Accurate implant position data, when combined with an IOS scan of the soft tissue (gums), allows the lab to design the prosthesis without needing a physical model.
Reduced Remakes: The high precision virtually eliminates errors in the impression stage, drastically cutting down on costly, time-consuming remakes.
Predictable Delivery: By knowing the implant positions are accurate to the micrometer, clinicians can proceed with confidence, often leading to a smoother and faster final delivery for the patient.
Photogrammetry is transforming full arch implantology, ensuring that the foundation of a new smile is built on the most reliable and precise digital data available.
