Weasis and Horos are the two free, open-source DICOM viewers that dental teams recommend most often. Both open CBCT and X-ray studies from any vendor, and both can build a panoramic-style view with cross-sections from a CBCT. The deciding differences are platform, 3D export and how actively each project ships.
The short answer: choose Weasis if any computer in your clinic runs Windows or Linux, if you connect to a PACS or DICOMweb server, or if you want a viewer that is updated several times a year. Choose Horos if everyone works on Macs and you want to export a 3D surface as STL without a second program. Neither is a certified diagnostic device, so both belong in review, referral, teaching and research work.
Side by side
| Item | Weasis | Horos |
|---|---|---|
| Licence | Free, open source (EPL 2.0 / Apache 2.0) | Free, open source (LGPL 3.0) |
| Platforms | Windows 10+, macOS (11+ Intel, 12+ Apple Silicon), Linux | macOS only (10.11 or later); Apple Silicon and Intel builds |
| Current version | 4.7.3 (August 2026) | 4.0.1 for Apple Silicon (installer from 2023); Intel build 4.0.0 RC5 |
| CBCT MPR | Oblique MPR with MIP, MinIP and mean projections | Orthogonal and oblique MPR |
| Panoramic view from CBCT | Curved MPR documented for the dental arch, with cross-sections | Curved MPR with straightened reformation and cross-sections |
| 3D | Volume rendering with presets | Volume and surface rendering |
| STL export | No (STL can only be imported and wrapped as DICOM) | Yes, plus OBJ and VRML |
| PACS | Query/retrieve (C-FIND, C-GET, C-MOVE), send, DICOMweb | Query/retrieve and send to DICOM nodes |
| Sharing | Export DICOMDIR, ZIP or ISO with the viewer embedded | Burn studies to CD/DVD |
| Regulatory | Not a certified medical device (CE or FDA), per the developers | No FDA or CE claim |
Opening a CBCT disc from another clinic
Both handle the everyday job well. Copy the disc contents to a local folder first, because reading a volume from an optical disc is slow. In Weasis, import the folder or the DICOMDIR file and open the series; Weasis reads JPEG, JPEG-LS, JPEG 2000 and JPEG-XL compressed images, which covers most vendor exports. In Horos, drag the folder into the database window, wait for the study to appear and open it in the 2D viewer. The Horos database approach suits a practice that keeps a local archive of received scans. Weasis feels closer to a simple open-and-view tool. If the disc came from a Planmeca clinic, the free Planmeca Romexis Viewer is also worth a try.
Building a panoramic view and cross-sections
This is the task that separates both tools from general viewers such as RadiAnt, which has no curved reconstruction. The workflow is almost the same in each. Pick an axial slice at root level, click points along the centre of the arch, and the viewer produces a panoramic-style reformation plus slices perpendicular to the curve. Step through the cross-sections and measure bone height and width with the length tool. Weasis documents this curved MPR specifically for tracing the dental arch on a CBCT. Horos calls it CPR and offers straightened and stretched reformations. For reviewing a site before a referral, the result is comparable. Neither tool includes implant libraries, nerve-canal tools or guide design; that belongs in implant planning software.
3D rendering and printed models
Here Horos has the clear edge. It renders both volumes and surfaces, and it exports a surface as STL, OBJ or VRML. Set a threshold that separates bone or teeth from soft tissue, export, then clean the mesh in MeshLab before printing. CBCT grey values are not calibrated like medical CT, so choose the threshold by eye and check the result. Weasis offers 3D volume rendering with presets and adjustable lookup tables, which is fine for showing a patient an impacted tooth, but it does not export STL. If you work in Weasis and need a model, add InVesalius for simple DICOM-to-STL work or 3D Slicer for automatic tooth and jaw segmentation.
PACS, referrals and sharing
Weasis is the stronger networked tool. It supports C-FIND, C-GET and C-MOVE for query/retrieve, sends studies to a PACS and speaks DICOMweb (QIDO-RS, WADO-RS, STOW-RS). For referrals, it exports a study as an ISO image with Weasis embedded, so the recipient can open it without installing vendor software. Its Dicomizer turns intraoral photos, PDF reports and STL scans into DICOM objects stored with the patient’s imaging. Horos also queries PACS and sends to other DICOM nodes, and it burns studies to CD or DVD. Purview, its chief sponsor, offers an optional paid cloud sharing and reporting service through the HorosCloud plug-in.
Mixed clinics and IT deployment
Horos runs only on macOS, with no Windows, Linux or mobile version. That alone settles the question for most mixed practices. Weasis installs as an MSI on Windows 10 or later, and IT staff can deploy it with winget install WeasisTeam.Weasis or Chocolatey. On macOS it is a PKG per processor type or brew install --cask weasis, and on Linux there are DEB, RPM, Flatpak and Snap packages. Current builds bundle their own Java. One Horos-specific warning: do not keep its database in iCloud, because the project says syncing it between Macs with the same Apple ID can corrupt the database or overwrite images.
Updates and support
Weasis ships several releases a year; 4.7.3 came out in August 2026. Horos releases are infrequent. The Apple Silicon installer dates from 2023, although the project promotes 4.0.1 for macOS 26 Tahoe and the source code received macOS build fixes in 2026. Both rely on community help. For Horos, the detailed user guide, training and direct support are paid services from Purview.
Which one should you use
- Windows or Linux anywhere in the practice: Weasis. Horos is not an option there.
- Mac-only practice that prints models: Horos, for built-in STL export.
- Clinic with a PACS or DICOMweb server: Weasis.
- Mac-only practice that just reviews referrals: either works; Weasis has the more active release cycle, Horos the local study database.
- Dental school or teaching lab with mixed computers: Weasis, so every student uses the same tool.
For more Mac options, see free DICOM viewers for Mac. For the full field, including browser-based and legacy tools, see free dental imaging software.
FAQ
Is Weasis or Horos better for dental CBCT?
Both open CBCT and build panoramic views with cross-sections. Weasis wins on platforms and PACS; Horos wins on STL export.
Is there Horos for Windows?
No. Horos runs only on macOS. On Windows, Weasis is the closest free alternative.
Are Weasis and Horos free?
Yes. Weasis is open source under EPL 2.0 and Apache 2.0, and Horos under LGPL 3.0. Horos accepts optional donations.
Can Weasis export STL?
No. Weasis can import an STL file and wrap it as DICOM, but it does not export 3D models. Use Horos, InVesalius or 3D Slicer for that.
Can I use Weasis or Horos for diagnosis?
The Weasis developers state that the open-source build is not a certified medical device, and Horos makes no FDA or CE claim. Follow your local rules for primary diagnosis.
Last updated: 26 September 2026 · DentIIT editorial team. Licence, version and platform details are checked against each developer's official documentation; none of the tools listed here should be treated as a certified medical device unless its vendor says so.
