How to clean up meshes with the brush tools in Cympha Studio

The three Cympha Studio cleanup brushes repair one patch of a scan, such as a residual attachment bump or artefact, and leave the rest of the mesh in the dental case as it was.

Audience: Clinicians and lab designers who need targeted local cleanup — removing a residual attachment bump, a scanner artefact, an over-extension at the gingival margin, or speckle noise on a specific patch — without rebuilding the whole mesh. The classic use case is a post-treatment scan where attachments have already been clinically removed but the scan still shows the bumps.

You'll come away knowing: how to start a brush session from the mesh right-click menu, how the shared brush controls work (size, hover preview, stroke), the three brush modes (Smart cleanup…, Delete region…, Local smoothing…) and what each does differently, when to pick each one, and the typical attachment-bump removal workflow.

Time required: Two to five minutes for a single attachment bump. Longer for a full arch of attachments — each one is a separate stroke.

Before you start

You need:

A mesh already added to the scene via Add model (+), ☰ Open optical scan file…, or drag-and-drop. Formats: .stl, .ply, .obj.
No GuideMia case loaded — the brush cleanup commands appear on the right-click menu only for user-added meshes when no full .gvw case is open. Use ☰ → Clear scene if you have one open.
A desktop browser with a mouse and a scroll wheel. The brush is driven by left-drag strokes on the 3D canvas and resized with the wheel; a touchpad without a scroll wheel can do it but the wheel-based brush sizing is much faster on a real mouse.
A backup of the original file. Brush strokes are applied immediately. <kbd>Ctrl</kbd>+<kbd>Z</kbd> restores the previous geometry, but it's a one-step undo — if a stroke went wrong two edits ago, the recovery is reimporting the source mesh.

Sign into studio.cympha.com and open your mesh.

Brush vs whole-surface. Whole-surface commands like Fix model, Fill holes, and Smooth can't tell whether a spike is noise or anatomy, so they treat the entire mesh the same way. The brush exists when you can see exactly where the defect is and want to leave the rest of the surface untouched.

When to use which brush mode

Three brush modes live on the right-click menu of a user-added mesh. The shared behaviour is identical (same brush, same stroke model, same release-to-apply timing — covered in Step 2 below). What differs is what happens to the triangles you paint:

| Mode | Per-stroke behaviour | Hole fill after delete? | Best for | |---|---|---|---| | Smart cleanup… | Auto: deletes painted triangles or smooths them — Studio decides per stroke based on how much of the painted region sits on an open boundary | Yes — closes the resulting hole automatically | Mixed defects where you don't want to think about delete vs smooth | | Delete region… | Always removes the painted triangles and runs the hole fill — every stroke cuts and closes, never smooths | Yes | Forcing a cut when you already know the material must go | | Local smoothing… | Always smooths the painted region — never deletes triangles | n/a | Relaxing noise on anatomy you don't want to remove |

Pick Smart cleanup… for the everyday case — most defects are either obviously a hole edge (delete + fill) or obviously a noisy patch (smooth), and Smart cleanup classifies them correctly without you having to choose.

Pick Delete region… when you already know the painted material must go and don't want the per-stroke classification — every stroke removes what you painted and closes the opening it left.

Pick Local smoothing… when the defect is noise and you want to be sure no triangle gets deleted no matter what — for example, smoothing the surface of a tooth without risk of scraping its crown edge.

Step 1 — Start a brush session

Right-click the mesh in the main 3D view.
In the context menu, choose Smart cleanup…, Delete region…, or Local smoothing… depending on what you want to do.
The viewer enters brush mode. The positioning gizmo and the distance tool are torn down automatically so clicks go to the brush rather than to those tools.
A circular cyan ring appears around the pointer when it's over the 3D canvas — that's the brush footprint.
The status line shows readiness; for Smart cleanup it typically reads "Ready" between strokes.

The brush only works on the mesh you started it from. If you have two arches in the scene, only the mesh you right-clicked is editable in this brush session. To clean the other arch, exit (right-click on the 3D view to cancel) and start the brush again from that mesh's context menu.

Step 2 — Master the shared brush controls

These controls work the same way in all three modes.

The brush ring follows your pointer

The cyan ring is the brush footprint in screen pixels, not millimetres on the tooth. That means:

Zooming the camera closer makes the same brush cover less anatomy in mm.
Zooming out makes it cover more anatomy in mm.

For a fine touch, dolly close to the surface before painting; for a broad sweep, pull the camera back.

Resize the brush with the mouse wheel

With the brush active and the pointer over the 3D canvas (the WebGL area, not the side panels):

Roll the scroll wheel to change the ring size — one direction enlarges, the other shrinks, a small step per notch.
If your mouse or trackpad uses inverted scrolling, try both directions once to learn which way grows the brush in your setup.
The radius is clamped between a small minimum (for fine work) and a large maximum (for sweeping a wide area).
Wheel events inside the canvas are captured by the brush, so resizing takes priority over scene zoom while the pointer is in the viewport. Move the pointer outside the canvas if you want to wheel-zoom the page.

Paint a stroke

Press and hold the left mouse button on the mesh surface.
Drag along the area you want to edit. Brush discs are stamped along the path so fast cursor jumps still leave a continuous painted region.
While the button is held, a faint cyan tint shows the union of every disc painted in the current stroke — that's your preview of what's about to be edited.
Release the left button. Only on release does Studio collect the affected triangles, run the cleanup logic for the current mode, update the geometry, and persist the result.

Between strokes you can keep painting more — there's no need to reopen the menu — until you exit brush mode.

Exit brush mode

Right-click anywhere on the main 3D viewer. The brush cancels and the status line shows "Clean up cancelled." The normal mesh context menu is suppressed for that click so the brush stops cleanly — right-click again afterward if you want the menu back.

Geometry note. After each painted stroke, Studio keeps only the largest connected group of triangles hit by the brush mask. That stops accidental picks on a back-facing sheet or a second shell from getting edited at the same time — so if you paint through a thin wall, only the front side is touched.

Step 3 — Mode-specific behaviour

Smart cleanup…

For each finished stroke, Studio checks how much of your painted region lies on the mesh's open boundary (edges adjacent to a hole):

If the painted region sits substantially on an open boundary, the stroke is treated as delete: those triangles are removed, then the hole-fill filter runs to close the opening.
Otherwise the stroke smooths only the painted region.

If a stroke produced nothing useful you may see "Smart cleanup: nothing to apply for this stroke …" in the status line, with a note about which path (delete vs smooth) was auto-chosen so you can adjust your next stroke. If you don't like the automatic choice, paint again or switch to Delete region… / Local smoothing… to force the behaviour you want.

Delete region…

Every stroke removes the painted triangles and runs the hole fill — the same delete path Smart cleanup takes, but unconditionally. Use it when you want every stroke to cut and close, never smooth. When you exit the tool, the largest connected piece is kept if anything became disconnected.

Local smoothing…

Every stroke only smooths the painted region (the same smoothing as Smart cleanup's smooth path). Triangles are never deleted, no matter what you paint. This is the safest mode when you only want to relax noise — there's no way to accidentally cut into anatomy.

The typical attachment-bump removal workflow

This is the most common reason designers reach for the brush: a post-debond scan still shows the bumps from clinical attachments and you want to remove them so the model reads as a clean post-treatment arch.

Add model with the post-treatment scan.
Optionally run Fix model first if the scan has small holes elsewhere — see How to repair a mesh with Fix model. Skip this if the only defect is the attachment bumps.
Dolly the camera close to the first attachment so the bump fills a comfortable fraction of the view.
Right-click the mesh → Smart cleanup….
Wheel the brush size so the ring is just large enough to cover the bump in one stroke, with a thin margin onto healthy enamel.
Press and drag across the bump in one continuous stroke; release.
Smart cleanup will typically classify this as "delete" (the bump is a raised region that the rim makes locally open after deletion) and close the resulting hole automatically. The bump should be replaced with smooth enamel.
If the first stroke didn't get all of it, paint again — incremental strokes are safer than one big stroke.
Move to the next tooth's attachment and repeat.
When all bumps are gone, right-click on the 3D view to exit brush mode.
Optional: run Fix model or Smooth at the end if you want a final polish over the whole mesh.

If a stroke leaves a visible crater or a sharp edge:

Switch modes to Local smoothing… and gently smooth the patch.
Or switch to Delete region… and trim the rim back further.

If a stroke removes too much material, stop painting. Further delete strokes will compound the loss. Press <kbd>Ctrl</kbd>+<kbd>Z</kbd> to restore the geometry before that stroke — it's a one-step undo, so use it right away — or reimport the original file and start over, this time with a smaller brush.

What success looks like

Defects you intended to remove are gone; the surrounding surface is untouched.
The status line cycles between "Ready" and per-stroke confirmation messages.
The mesh entry in Models is still present and visible.
Between strokes you can rotate the camera (right-drag and middle-drag still work in brush mode; only left button is captured for painting) to inspect from another angle before continuing.

Troubleshooting

The right-click menu doesn't show the brush options. A GuideMia case is loaded — clear the scene with ☰ → Clear scene, or you right-clicked on case geometry rather than a user-added mesh.

Status line says "Clean up: empty stroke — drag on the model with the brush." You clicked without dragging far enough for the brush to stamp any discs. Press and drag, don't just click.

Status line says "Clean up: no mesh triangles under the painted mask — paint on the surface." Your strokes happened off the mesh — for example over background or over a hole. Aim for the surface; the cyan tint preview tells you what's actually being painted.

Smart cleanup smoothed when I wanted it to delete (or vice versa). The auto rule looks at boundary triangles in your painted region. To force delete-and-fill behaviour, use Delete region…; to force smooth-only, use Local smoothing…. There's no in-mode override.

A stroke removed material I wanted to keep. Stop painting and press <kbd>Ctrl</kbd>+<kbd>Z</kbd> straight away — geometry edits keep exactly one step of undo, restoring the mesh as it was before the stroke. If you've painted again since, reimport the original mesh and restart with a smaller brush.

The brush ring jumps to a back face and edits the wrong side. The "keep largest connected group" rule usually prevents this, but on very thin walls it can pick the back face. Rotate the view so the front face is unambiguously closest before painting.

The wheel zooms the scene instead of resizing the brush. The pointer was outside the 3D canvas when you scrolled. Move the pointer into the WebGL viewport before scrolling.

The context menu won't close when I right-click on the 3D view. That's by design while brush mode is active — right-click cancels the brush rather than opening the menu. Right-click again after the "Clean up cancelled." message to get the normal context menu back.

Distance measurement or the gizmo disappeared when I started the brush. Both are torn down when brush mode starts so clicks go to the brush. They come back after you exit brush mode (right-click on the 3D view).