Written for dentists and dental technicians, based on the clinical meeting between Khai Nguyen Dental Lab and Vien Dong Dental Clinic (October 2025), the seminar with Viet Dang (March 2026) and the full-arch cases the lab produces.
Recording implant positions for a full arch is the step where most cases go wrong. With four to six implants in one arch, a single abutment misplaced by a few tens of microns leaves the framework without passive fit, and all the esthetic work that follows becomes pointless. Intraoral photogrammetry (IPG) is the approach increasingly used to solve this, and it is the topic Khai Nguyen discussed with the clinicians of Vien Dong Dental Clinic and brought into the March 2026 seminar.
Three ways to record a full arch, and the limits of each
| Method | Principle | Limitations |
|---|---|---|
| Conventional splinted impression | Copings screwed to the abutments, splinted with resin or a metal bar, impressed in silicone | Resin shrinks, the impression distorts on removal, results depend heavily on technique; a model must be poured and verified at the lab |
| Intraoral scan with scan bodies | The scanner captures the scan bodies and stitches them into implant positions | Error accumulates with distance: excellent for one to three adjacent implants, less reliable across a long arch with no anatomical reference points in a fully edentulous patient |
| Intraoral photogrammetry (IPG) | A dedicated camera takes many images of markers screwed to the abutments from different angles; software computes the three-dimensional position of each abutment | Gives implant positions only, not soft-tissue contour or the opposing arch; requires dedicated equipment and must be combined with a soft-tissue scan |
Photo above: Clinical meeting on photogrammetry for full-arch implant restorations with Vien Dong Dental Clinic, October 2025.
What IPG solves
The strength of photogrammetry is that accuracy does not degrade with the distance between abutments. Because the system computes each marker’s position by intersection from images taken at different angles, error does not accumulate along the arch as it does when consecutive scan frames are stitched. In a fully edentulous arch, where no natural teeth provide stitching references, this is the decisive difference.
For the lab, IPG data means implant positions arrive digitally and already verified, so verification-jig checks on the model shorten considerably or need not be repeated. That is why cases such as the full-arch zirconia overlay on a titanium iBar or upper and lower All-on-X can go straight into design instead of waiting through several framework try-ins.
Clinic and lab workflow
- Remove the provisional and attach photogrammetry markers to the multi-unit abutments. Check they are fully tightened and do not obscure one another at the capture angles.
- Capture with the photogrammetry device. It computes the three-dimensional position of each abutment and exports an implant position file.
- Scan the soft tissue and the opposing arch. This step cannot be skipped: IPG gives abutment positions, while gingival contour, ridge form and the opposing arch must come from an intraoral scan.
- Scan the provisional if the patient is wearing one comfortably; it is the most valuable data on vertical dimension, smile line and lip support.
- Send the lab three data sets plus facial photos: the implant position file, the soft-tissue and opposing scans, and the provisional scan.
- The lab merges the data, aligning implant positions to the soft-tissue scan, designs the teeth first, then reduces to a framework or bar, mills and checks passive fit.
What IPG does not replace
- It does not replace the soft-tissue scan. Many cases arrive without it, leaving the lab with abutment positions but no gingival contour for designing the tissue surface.
- It does not replace a clinical fit check. For a full-arch bridge, an intraoral single-screw test remains the final check before the ceramic work is completed.
- It does not replace esthetic information. Vertical dimension, midline and lip support still have to be established by the dentist, usually through provisionals.
If you do not have photogrammetry equipment
Full-arch cases are entirely feasible without it. Khai Nguyen accepts all three data types: conventional splinted impressions, intraoral scans with scan bodies, and IPG files. For the first two the lab will propose a verification jig for an intraoral check before the framework is milled, and this step is worth keeping: a verification jig costs far less than re-milling a titanium bar.
To discuss the data workflow for a full-arch case, contact us on WhatsApp +84 902 945 585. See also bar-supported full-arch restorations and the scan file formats we accept.
Source: Khai Nguyen Dental Lab Facebook page, posts of 3 October 2025 and 28 February 2026.
