Many times, the loss of a tooth is not because of bad oral hygiene, or any sort of habits, but because of a trauma. Traumas, by their very nature are accidental and thus cannot be calculated upon or somehow avoided with easy steps. But there are certain cases where you can do things to prevent these traumas form occurring. One of these instances is sports: if you are playing sports that involves a ball, or is a contact sport in any way, you should use a mouthguard to play it, in order to protect your teeth, as a just in case.
Why use them
Mouthguards provide protection for your teeth, that much must be very obvious, because they cover them in a layer of hard plastic that is much more resistant to force and pressure, not to mention flying objects and someone’s elbow or knee, and the ground than just your tooth enamel. Using them is super cheap, as a mouthguard can be bought with pocket change, but getting broken teeth replaced can be much more than anticipated. Getting a broken tooth restored means getting a root canal treatment, a dental crown, and some dental treatments to stabilise your condition, as the gums are almost invariably damaged from traumas to the mouth. And this is a best case scenario! If you really have a doozy, you will have to get a surgical extraction of the tooth and replace with a dental implant, which can end up costing you thousands of pounds. Aside from this very basic and obvious example, they can help with bruxism as well. If you tend to grind your teeth when you are concentrating or exerting effort, as most people do, then you can definitely benefit from the use of a mouthguard.
Where to get them, how to keep them clean
Mouthguards are available at all sports stores and pharmacies as well, and many other places will have them randomly, from time to time. You should buy one that you always wash out after use, so that bacteria do not start to live in it, and it does not end up infecting your mouth instead of protecting it. Soak it from time to time in mouthwash, and rinse it very thoroughly after every use, and you should have no problems with it.