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Many civilians as well as military personnel are familiar with the term 4-F (also called 4F). 4-F is a classification given to a new U.S. military registrant indicating that he or she is “not acceptable for service in the Armed Forces” due to medical, dental, or other reasons.

Most people do not know that the term 4-F (or 4F) originated in the Civil War and was used to disqualify army recruits who did not have four front teeth with which to tear open gunpowder packages.

History of the term 4F or 4-F

The term 4F or 4-F started in the Civil War. As both Confederate and Union soldiers were being recruited, there were very few medical or dental reasons for rejection. Quite simply, the battery of tests and screening tools available today simply did not exist back then.

It was noted, however, that in order to properly load a rifle quickly, the gun powder cartridge needed to be ripped open with the teeth. Molars and premolars in the back of the mouth were not sufficient for this task. Only the incisors and canine teeth in the front could be utilized.

Back then, routine dental care did not exist, and many people in their late teens and 20s were missing several teeth. If a recruit could not open the gun powder cartridge with his teeth, he would not be able to reload quickly, placing himself and his fellow soldiers at greater risk.

So, while evaluating new registrants, a dental exam was performed to see if each young man had at least four front teeth. The dentist would examine the young man and evaluate the front teeth (or lack thereof). Those young men without four front teeth were disqualified and not permitted to enlist.

Naturally, a “code” was needed to designate why the registrant was unfit for service. So someone (presumably a Union Officer) came up with:

4-F (lacks 4 Front Teeth)

And from that point forward, the term 4-F was used in this manner.

Use of 4-F in the Military Today

After the Civil War, the term 4-F (4F) continued to be used to disqualify possible recruits for medical, dental, or other health reasons. As time progressed and more was learned about medicine and dentistry, new screening criteria was developed. In addition, with the development of new rifle technology, one no longer needed four front teeth to efficiently fire and re-load a rifle. So the “four front teeth” criteria was eliminated. The term 4-F was used by the Selective Service System extensively in World War II and that is when it entered the vocabulary of most Americans.

As a general dentist in private practice, I have the privilege of treating all types of members of the Armed Services. Frequently I have to examine a patient and complete a Pre-Deployment Dental Screening Form and certify that the patient has no acute dental problems that would interfere with his/her ability to serve in the military. I feel honored to have this privilege and I take this responsibility quite seriously. As of this day, I have yet to see a patient about to deploy without at least 4 front teeth. But if so, it would not disqualify them from service. But I hope I never see that!