iPhone face scan for smile design in exocad and other CAD

A smile designed only on an intraoral scan is designed without the face around it. Midline, incisal plane, lip support and tooth display all depend on the patient’s face and a 3D face scan brings that reference into the CAD. This used to require dedicated hardware. Today an iPhone app can capture a face scan that is good enough for most smile design work and this post explains how to capture it, how it is aligned with the intraoral scans and where its limits are.

What a face scan adds to smile design

In 3D, the facial midline, the interpupillary line and the smile line can be read directly instead of being estimated from a photo. Tooth length and width can be judged against the lips and the whole face. The patient sees the proposal on their own face, which makes it easier to discuss. And the technician works with the same view of the patient as the clinician.

Face scan apps for iPhone

After Bellus3D retired its dental app, other apps took its place. Qlone Dental Pro is an iPhone app focused on face scans for dental CAD. It exports OBJ, STL and PLY files and works with exocad, 3Shape, Blue Sky Plan, Medit and other software.

A phone app does not match every dedicated face scanner. It costs a fraction of one, though, and for smile design and communication its quality is often sufficient.

How to capture a usable face scan

Use even, soft light and avoid strong side light or backlight.
Keep the patient still, with eyes open and the head in a neutral posture.
Ask the patient to remove glasses and pull hair away from the forehead and ears.
Capture several expressions: at rest, a full smile and a smile with lip retractors.
Make sure the retracted scan shows the teeth clearly, since the alignment with the intraoral scan depends on it.
Check the result before the patient leaves, while a new capture is still easy.

From face scan to smile design

Export in a format that keeps the texture, OBJ or PLY.
Import the face scans into the CAD together with the intraoral scans.
Align the retracted face scan to the intraoral scan on the teeth, then align the smiling and resting scans to the retracted one.
Set the references: midline, horizontal plane and smile line.
Design the teeth in 2D and 3D against the face, then refine the anatomy on the intraoral scan.
Transfer the design to the mouth with a mock-up, so patient and clinician can verify it.

In exocad this workflow runs in the Smile Creator module, which is described in the exocad Smile Creator guide. For the lab side of the process, see digital smile design in the dental lab.

Limits of phone face scans

Scan quality varies with light, patient movement and the person holding the phone. Fine details, such as the lips during movement, are approximate. A face scan is a visual reference and should not be used as a measuring instrument for critical clinical decisions. It is also patient data, so it has to be stored and shared under the same privacy rules as any other clinical record.

Within those limits, a phone face scan is an inexpensive addition that improves most aesthetic cases. For the file formats involved, see STL vs PLY vs OBJ.

Frequently asked questions

Can an iPhone replace a dedicated face scanner?

For smile design and patient communication it is often enough. Dedicated scanners give more control and repeatability, which matters in complex rehabilitations and whenever measurements are critical.

Which file formats do face scan apps export?

Qlone Dental Pro exports OBJ, STL and PLY. OBJ and PLY keep the color texture, which is what smile design needs.

How is the face scan aligned with the intraoral scan?

Usually on the visible teeth. A face scan taken with lip retractors shows the teeth clearly and corresponding points on the teeth align it with the intraoral scan.

Which CAD software can use face scans?

exocad, 3Shape, Blue Sky Plan, Medit and Blender for Dental can all work with imported face scans. In exocad the Smile Creator module is designed for this workflow.