3D Scanning and Photogrammetry: How We Record Your Mouth Digitally

For most of the last century, taking a dental impression meant a tray of setting putty held in your mouth while you tried not to gag. It worked, but it had a weakness nobody could design away: the material itself moves. It shrinks slightly as it sets, distorts a little on removal, and moves again when the plaster model is poured. Each of those steps is small. They add up.

Digital scanning removes the material from the chain. Instead of copying your mouth in putty and then copying the putty in plaster, the shape is measured directly and stored as a file. We use two different digital techniques, for two genuinely different jobs, and this guide explains what each one does and when it matters to you.

Photogrammetry solves a different problem, and it solves it in a completely different way. Rather than mapping surfaces, it measures positions.

Small coded markers — often called scan flags — are screwed onto each implant. A camera then photographs them from many angles in quick succession. Because the geometry of each marker is known exactly, software can triangulate from those images the precise three-dimensional coordinates and angulation of every implant relative to every other one.

Crucially, there is no stitching. Every implant is measured against the same single frame of reference, so error does not accumulate along the arch. Across a full jaw, photogrammetry is the more reliable of the two techniques for recording implant positions.

What photogrammetry does not capture

It records implant coordinates and nothing else — no gum contour, no soft tissue, no opposing teeth. On its own it cannot be used to make anything. In practice the two records are merged: photogrammetry supplies the implant positions, the intraoral scan supplies the soft tissue and the bite, and the laboratory designs on the combination.

The two techniques are not competitors. They answer different questions, and a full-arch case needs both answers.

From the chair, the practical differences are straightforward.

• No impression trays. Nothing sets in your mouth, so the gag reflex that makes some people dread impressions is largely avoided.
• Faster, and repeatable in seconds. If one area is unclear, that section is rescanned in moments rather than the whole impression being retaken.
• You can see it immediately. The model appears on screen as it is captured, so wear, cracks, recession and bite problems can be shown to you rather than described.
• Fewer remakes. Digital records are checked for completeness before you leave the chair, instead of a laboratory discovering a flaw days later.
• Files travel. Your scan can be sent to a laboratory or, if you are planning treatment from abroad, reviewed before you fly. Our treatment journey guide explains how this fits into the visit schedule.

One honest caveat: digital scanning is not automatically better in every situation. Deep margins sitting below the gum line, or a field that cannot be kept dry, can still defeat an optical scanner, and in those cases a conventional impression remains the right clinical choice. The technique should be chosen for the case, not for the brochure.