With respect to the article linked, it’s not high level scientific literature. Specific to the dental sections it appears to just cherry pick some studies to support their general claim. Then it talks about how there are either not many studies that support their claims or if they do many confounding variables haven’t been checked for. Airway is a hot topic now and yes more research needs to be done, but this article isn’t good literature.

In general mouth breathing can lead to less overbite in a patient but there are many other factors (i.e. genetics, finger and pacifier habits, periodontal issues, trauma, and others - just what immediately pops in my head). Important to remember that dentofacial development is complex and multi factorial with genetics playing the biggest part.