How to simulate lateral excursion in Cympha Studio

Articulation simulation in Cympha Studio plays a lateral excursion from paired upper and lower scans, so you can check the contacts on the dental case in the browser.

Audience: Orthodontists, prosthodontists, and lab designers who want a quick visual check of how the mandible moves laterally relative to the maxilla — for consult discussions, plan sanity-checks, or occlusal clearance review.

You'll come away knowing: how to start an articulation session from either a loaded OrthoPlus case or two standalone jaw scans, how to position the occlusal reference plane, how to scrub the simulation, and how to read the clearance / collision graph at a high level.

Time required: Around five to ten minutes once your scans are loaded. Loading and registering the scans is what takes time — the articulation itself is fast.

Before you start

Studio's lateral excursion is a visual review tool, not a TMJ diagnostic or a substitute for a physical articulator. It animates a lateral mandibular path against a translucent occlusal plane and shows a small graph of penetration / left gap / right gap as the simulation plays.

You need one of these starting conditions:

An OrthoPlus plan (.gvw) loaded in Studio. Both upper and lower teeth are already part of the case, so no extra scan files are needed.
Two jaw mesh files — typically an upper arch and a lower arch from the same patient, taken in occlusion or close to it.

Open studio.cympha.com. No account or sign-in is needed for anything in this workflow.

Path A — Articulation from an OrthoPlus case

This is the fastest path. The case already contains upper and lower tooth meshes in the same coordinate frame.

Load the case: ☰ → Open OrthoPlus plan…, pick a .gvw file. Wait for the case to finish loading; the arch toolbar and the floating case bar appear once it's ready.
Make sure both jaws are visible (Both arches on the arch toolbar at the top-center, not just Upper or Lower).
Click the articulation icon (the jaw icon) on the top toolbar.
Studio prepares the case session — it merges the upper and lower tooth surfaces and computes a default occlusal reference plane. The plane appears in the 3D view as a translucent rectangle with a normal arrow and drag handles.
The Simulate articulation dock opens, with a graph (collision / left gap / right gap), a lateral limit field in millimetres, and Run / Stop buttons.

The icon never opens a file picker. With a .gvw case loaded it always uses the case. With no case loaded and no stored mesh pair, the icon shows a hint on the status line explaining what to do — that's normal, not an error.

Path B — Articulation from two standalone jaw scans

Use this when you have an upper and a lower arch scan but no full OrthoPlus case. These are the only two ways into a simulation — a .gvw case, or exactly two meshes loaded through this menu item.

☰ → Simulate articulation….
The file picker opens. Select exactly two mesh files (upper and lower jaw scans). Three is too many, one is too few — Studio rejects other counts with a status-line message.
Both meshes load into the scene. Studio remembers them as the articulation pair for the rest of the session.
The occlusal reference plane appears and the Simulate articulation dock opens, same as in Path A.

Later in the same session, if you close the dock or do other work, you can click the articulation icon on the top toolbar to reopen the simulation without the file picker — Studio uses the stored pair as long as both meshes are still present.

Step — Position the occlusal reference plane

The translucent plane defines the occlusal reference for the simulation. Get its position and orientation roughly right before pressing Run.

The arrow on the plane is its normal vector. It must point toward the upper jaw. Follow the in-app hints if you're unsure which side the arrow is on.
Drag the plane handles to translate or tilt it. For an OrthoPlus case, default placement follows the app's case rules and is usually close enough that only minor adjustment is needed.
For two standalone scans, the default plane is computed from the meshes' bounds — you may need to tilt it to match the patient's natural occlusal plane (roughly the line from the incisal edges to the molar cusps, parallel to Camper's plane in most patients).
User adjustments are kept for the rest of that case session.

Step — Set the lateral limit and run

In the Simulate articulation dock:

Set Lateral limit in millimetres — how far the lateral excursion sweeps.
Click Run. Playback begins from the centric (approximately zero lateral excursion) frame along the path.
Watch the 3D view as the lower jaw sweeps laterally against the plane. The graph in the dock updates as it plays — showing collision (negative clearance — tooth-on-tooth interference), left gap, and right gap as the excursion progresses.
Click Stop when you've seen what you need to see.

How to read the graph

The graph is a high-level summary, not a precise contact map.

Collision (red region in the convention shown) indicates interpenetration between the upper and lower surfaces at that lateral position — i.e., tooth-on-tooth interference.
Left gap and right gap are clearance values on the working and non-working sides. A clean lateral excursion in clear-aligner or balanced-occlusion plans shows non-zero gap on the balancing side as the excursion progresses.
A spike in collision near centric usually means the plane isn't quite right or the bite registration on the source scans is off. Adjust the plane and re-run, or re-articulate the source scans.

What success looks like

The simulation plays smoothly from one lateral extreme to the other and back, without the lower mesh visibly clipping through the plane.
The collision trace is reasonable for what you'd expect clinically — close-to-zero at centric (or showing only the contacts the plan calls for), increasing on the working side as the excursion progresses through canine-protected occlusion.
You can stop at any point in the excursion and inspect the contact geometry in 3D (rotate the camera with left-drag; pan with middle-drag; zoom with right-drag or scroll wheel).

Capturing what you found

Once you've found the view that shows the contact you want to discuss, click the camera icon (Screen capture) on the top toolbar. Studio captures the current viewer column as a PNG and prompts for an optional comment. The image lands in the Media gallery and travels with the project when you save as .cyp.

For a more complete record, save the whole project: ☰ → Save project as… writes a .cyp + asset folder including the meshes, the plane state, and any gallery captures.

Troubleshooting

The articulation icon does nothing — only a status-line hint. No .gvw case is loaded and no stored articulation pair is available. Use ☰ → Simulate articulation… to load two jaw files, or load an OrthoPlus case.

The plane arrow points the wrong way. Drag the plane handles to flip it so the normal arrow points toward the upper jaw. The in-app hints reinforce this — read them before Run.

Run does nothing, or the simulation jumps but doesn't animate. Usually the meshes are too far apart for the configured lateral limit, or the plane is positioned far from the occlusion. Bring the plane into the occlusal region and confirm the two meshes are actually in or near occlusion (use the gizmo on the moving mesh if needed).

Collision is enormous and constant. The two meshes are interpenetrating before the simulation even starts. Double-click the lower mesh and hinge it open with the gizmo until centric is clean, then re-run. Articulation expects a roughly closed bite as the starting pose.

The picker rejected my files. Simulate articulation… accepts exactly two mesh files in the same selection. One file or three files won't work — reselect exactly the upper and lower jaw scans.

I want to articulate a .pac step archive. .pac archives can drive the case bar's step playback but don't drive the same articulation path as .gvw. Convert the underlying case to .gvw if you need full articulation, or use Path B with the upper/lower meshes exported from the step archive.