Is this like head protection, where it's a necessary evil that no one tolerates?
I don't think a mouth guard can be compared to a helmet. I think it make a lot of sense to push for figure skaters to wear helmets. It is sad that the sport seems to discourage wearing a helmet, except at the very lowest (snowplow) levels.
On the other side, except in very special cases, it makes very little sense for a figure skater to wear a mouth guard. A large number of injuries in skating could be prevented with a helmet, very few would be prevented with a mouth guard. To me, it is just too rare to take a precaution against- there is some risk in every sport, you can't wrap yourself in bubble wrap, if you want to do that- you just can't participate. Sports are risky, it is their nature.
I asked my husband about mouth guards (I've never worn them) and he said the problem with them is they make it very difficult to breathe. The sports that wear them generally have quick action, and then a break- and you often see the players spitting them out as soon as they can. He said as a wrestler some people wore them, but he chose not too because of the inability to breathe, wrestling, like a figure skating long program, is constant action. You don't get the chance to remove it, swallow all the excess spit, take a deep breath and start again.
Because I read this thread last night, but hadn't replied yet, I watched for mouth guards at the hockey game I went to last night. I only saw visibly about 5 players who were wearing them. I imagine a few more had them in, but it looked like the vast majority did not. I actually looked today at the rules (wondering if I missed them) and they are NOT required as a piece of equipment for professionals. (Kids and college do require them.) This is a CONTACT sport (where I think it is kind of crazy not to wear them...) Again though, it wasn't constant action- the game moved continually, but they shuffled people in and out at an amazing rate, and the guys wearing the guards spit them out as soon as they were near the wall.
Figure skating is NOT a contact sport. Yes, there are some falls a mouth guard would have helped, but those falls are rare. I can understand an individual choosing to wear one, but unlike helmets, I don't think this is something that figure skating needs a big push to accept.
For someone with a special risk, like your implant, I could see it for a short period of time- but even still, I'm not sure the cost is worth the small chance of protection.