I honestly don't know. I don't have young children so the issue has never been discussed. But I am sure that if you wanted that kind of information, they would be more than happy to discuss it with you.
Sorry but I'm not a authority on that but my best guess is unfortunately they should wear them, no I'm not a fan believe kids and adults should enjoy the warmth of a smile but go with what you believe or feel, hope that helps as I work security I'm no doctor though I have slept in a Holiday Inn lol.
Thanks! Your answer is awaiting moderation.