The history of orthodontics has been intimately linked with the history of dentistry for more than 2000 years. Dentistry had its origins as a part of medicine.
Addressing an envelope to a post office box address is just like addressing envelopes to any other type of address. Of course, before you can address the envelope, you need the name of the recipient, the post office box number and the city, state and ZIP code.
The basic format consists of five decimal numerical digits. An extended ZIP+4 code, introduced in 1983, includes the five digits of the ZIP code, a hyphen, and four additional digits that determine a more specific location within a given ZIP code. The USPS provides a free online lookup tool for ZIP codes.