I have added this hook to the next beta update v15.1.22. Sadly, I can't backport the hook to a non-beta version. Hooks would require another release of a stable version and that is against our current policy.
In addition to the obvious buttons from Program Links, any number of hooks are allowed. We add them quickly and we backport them to the beta version so you can get going right away. Once we define a hook and what information it will pass, a plug-in can start to make use of it. We expect there to eventually be hooks in thousands of locations throughout the program. Almost anything can be done with hooks and plug-ins that can be done by directly altering the main program. Hooks are requested in the developer's forum. We do not add plug-ins to the OpenDentBusiness project.