Very unusual indeed...
You don't need to brush them... But they usually do need their teeth filed down on an increasing basis as they age... maybe every year as they get older. Bay has his done once a year, Cyn hasn't had hers done yet, and pony had hers done once since I've had her but hasn't needed it again yet.
Normally, the teeth continue to grow their whole lives, and if they had a perfect bite, they'd wear evenly, but they don't have a perfect bite, as you can see there ;~D
It usually isn't the front ones that cause painful problems, it's the back molars that you can barely see or feel to check out. Your vet can, and can tell you if and when to file that one. It doesn't look sharp edged... the back molars can develop really sharp points that scratch and scar up the inside of their cheek.