A risk related to oral jewelry is jewelry swallowing.
In general, swallowed jewelry passes harmlessly through the digestive tract within a few days, although in rare cases an object can become stuck, requiring either tube removal or surgery. While not recommended, if you swallow a bead or a ring there's not really much in the way of complications — outside of anxiety — that should be expected. If the entire bar is swallowed it could in theory damage your gastrointestinal tract, but this is rare.
If you swallow a bar or larger piece of jewelry, you should check your stools to make sure it passes (to put it simply, shit in a strainer and then sift for gold) and if you don't see the jewelry in a few days, call your doctor to get their opinion. Eating a high fiber diet - whole grain breads, cereals, fresh fruits and veggies - until you pass the jewelry is helpful. However, do not take any laxatives (although milk of magnesia is OK).
If you start throwing up, gagging, choking, etc., seek medical care immediately (assuming it's not just an anxiety attack). Same goes for if you have stomach pains, bleeding from your rectum or blood in your stools, or are running a temperature.