How to

Trace the dental arch for a panoramic view

After this page you will be able to draw your own arch on an axial slice, rebuild the panoramic view from it, and move a cross-section along the arch to see any tooth in its buccolingual plane.

What the Pano stage does

The Pano stage takes a curve you draw on an axial slice and samples the volume along that curve, averaging a thin slab, to produce a panoramic image. Below it sits a perpendicular cross-section driven by a yellow scout line. The demo scan ships with a default arch, so you can explore first and trace later. The imaging principle is explained in CBCT panoramic reconstruction; this page is about the hands-on part.

The curve is stored with the case, so once you are happy with it, it stays. Retrace whenever the curve misses the arch on a new scan.

Dragging the scout line, then retracing the arch with seven taps and tapping "Show panoramic".

Steps

Open a case and choose Pano. Use the segmented control at the top of the case (3D, MPR, Pano, Slice). The panoramic view appears on top, labelled "Panoramic" with edge labels R, L, H and F, and the cross-section below it.
Tap "Edit arch". The button sits at the bottom right of the cross-section pane. The stage switches to an axial slice with the edge labels R, L, A and P, and a hint asks you to tap along the dental arch with at least 4 points.
Tap your points from one molar region to the other. Start behind the last molar on one side, follow the centre of the alveolar process through the canine and incisor region, and finish behind the last molar on the other side. Four points is the minimum; six or seven give a smoother curve. Keep each tap on the arch itself, not on the buccal cortex.
Fix mistakes with Undo or Clear. "Undo" removes the last tap. "Clear" removes all of them so you can start over. Neither touches the stored arch until you confirm.
Tap "Show panoramic". The button becomes active once four points are placed. The panoramic view is rebuilt on the GPU and the cross-section reappears below it.
Drag the yellow scout line. Drag anywhere across the panoramic image, left or right. The cross-section follows and its label reads, for example, "Cross-section · 45 mm along arch". The number is the distance along the curve from its first point, so it increases from the patient's right side toward the left, following the OPG convention.

Reading the cross-section

The cross-section is cut perpendicular to the arch at the scout position. Buccal is on one side and lingual on the other, with the alveolar crest at the top and the inferior border of the mandible at the bottom. A scale ruler at the bottom left gives you a reference in millimetres. This is the view in which the mandibular canal is easiest to follow: move the scout line in small steps from the ramus forward and watch the round low-density canal travel from lingual to buccal before it reaches the mental foramen.

If you want to keep a particular cross-section, save it as a moment with "Save this view"; the moment stores the exact cut and replays in the Slice stage. See Save and replay moments.

If it does not work

"Show panoramic" stays greyed out. You have fewer than four points. Tap at least one more on the arch.

The panoramic view shows teeth cut off or doubled. The curve runs buccal or lingual of the roots. Tap "Edit arch", "Clear", and retrace with the points on the centre of the alveolar process. A slice at mid-root level helps.

One side of the arch is missing. Your first or last tap was too far forward. Start and end behind the last molars, even on an edentulous side like the left posterior region of the demo scan.

The scout line will not move. You are in arch editing mode. Finish with "Show panoramic" first, then drag on the panoramic image.

The companion page CBCT versus panoramic radiograph explains why a reconstructed panoramic image and a true OPG are not interchangeable.

Questions students ask

How many points do I need to trace the dental arch?

At least four. JawAtlas fits a smooth curve through your taps, so four to seven well-placed points from one molar region around the front to the other side are enough. More points do not make the panoramic view sharper; placing them on the arch does.

Which axial slice should I trace on?

One where you can see the roots of most teeth at once, roughly mid-root level. The curve is sampled through the full height of the volume, so a slice that shows the arch shape clearly matters more than any exact level.

Why does the panoramic view look different from a real OPG?

A panoramic radiograph is made by a moving tube and detector with a focal trough; the JawAtlas view is a slab sampled from the CBCT volume along your curve. Magnification and ghost images are absent, and the thickness of the slab is fixed. Both use the same OPG convention, patient right on the viewer's left.

JawAtlas is an education and training aid. It is not a medical device and must not be used for diagnosis, treatment planning or any clinical decision.

Last reviewed 2026-10-13