Ortho2 Edge Cloud

Ortho2 Edge Cloud is cloud-hosted orthodontic practice management software: scheduling, contracts, reminders, insurance and dashboards. Commercial software for orthodontic practices; Ortho2 offers a free on-demand video demo and custom demos.
OpenDentalFork21.2

OpenDentalFork21.2 is an unofficial GitHub copy of the Open Dental 21.2 source code (Windows, C#), uploaded in 2021 in four commits and never updated. There is no Cloud Edition. For clinics, use the official Open Dental instead.
OpenEMR

OpenEMR is a free, open-source (GPL v3) EHR and practice management system with scheduling, clinical records, e-prescribing, billing and a patient portal. It runs in Docker, on Linux or on Windows; staff use a browser. It has no built-in dental chart.
Dental Wings DWOS

DWOS from Dental Wings (Straumann Group) is open dental CAD/CAM software for labs: crowns, bridges, abutments, bars, partials, dentures, splints and models. Windows only. Commercial, with a trial licence available on request.
Open Dental

Open Dental (originally Free Dental) is dental practice management software for Windows: scheduling, charting, treatment plans, insurance claims and imaging. Shareware (conditionally free): free evaluation version limited to 30 patients.
Dolphin Imaging

Dolphin Imaging from Patterson Dental captures and organises ortho photos and X-rays, traces cephs and analyses CBCT data. It is commercial Windows software with a demo on request; the stand-alone Dolphin Imaging Viewer for referral doctors is free.
iDentist

iDentist is a cloud-synced dental practice app for iPhone, iPad, Mac, Android and Windows: appointment calendar, online booking, reminders, dental charts and patient records. Shareware (conditionally free): free trial, then a paid plan.