After catching a random knee to the chin and chipping a tooth as a white belt, I always wear a mouth guard. With the right choice of guard, it's low cost and low inconvenience that nearly eliminates the risk of a potentially high cost accident.

I highly recommend SISU, especially the second generation (nextgen), the thinner one is fine for BJJ but too little for striking.

Pros:

• ⁠Good protection, never had a problem with them.
• ⁠Very minimal, easy to breathe and speak through.
• ⁠Because I can speak well through them, then I don’t have to take them out ever on the mats (no nasty drops)
• ⁠Fit well (see below)
• ⁠Easy to refit many many times if having difficulties (up to 20x iirc)

Cons:

• ⁠Bit more pricy than shockdocs etc.
• ⁠Can be tricky to fit (see below)
• ⁠Gen 1 could develope sharp/abrasive edges.

Fitting tips:

Don’t use scalding water, just hot enough. After the time allotted to make the guard moldable, use a mirror to make sure you are centering the guard well. Gently suck on the guard and use your tongue to hold and mold it in place, don’t bite on it, just gently squeeze your teeth together. It’s easy to suck too hard and make it too tight. It will shrink slightly as it cools to body/room temp. After a couple of attempts, you’ll probably get it very close to a good fit but a bit on the tight side. Use your hand and teeth to leverage it and bend the sides (or just the front) slightly. This process has yielded a great fit for me at least.