Granted Patent
Utility
US 4,115,921 · App. 05/794,407
Extraoral force-applying orthodontic appliance
Inventor:
Maclay M. Armstrong
Patented Case
View Patent ↗
Granted: Sep 26, 1978
Filed: May 6, 1977
Inventor
Maclay M. Armstrong
Assignee (at issue)
Northwest Orthodontics, Inc.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.