Does anyone else say it's dorky or is it just you're opinion? Ask some people who'd give you a serious answer and not be a **** about it or lie because they're afraid it'd hurt your feelings. Now, there are only 2 possible outcomes and either way it works out fine.
Outcome #1:Everyone thinks your smile is goofy and it's a universal fact. No need to panic, smile anyways. You can easily joke about it, maybe make some comparisons between you and the 'MAD' comics guy. You can get away with just about anything if you make a good joke about it. Don't bring it up out of nowhere though, just when smiles come up in conversation feel free to make a joke about it. If you are trying to pick up a girl and she turns you down because you're smile is goofy, then great, you just saved yourself wasted time in some ho who wouldn't be worth your time. The guys with the good smiles gotta find out after weeks that the girl really was some ho, you can weed them out right away though
Outcome #2:It's all in your head and you're the only who thinks your smile is goofy because you are too self-conscience. I think this is very probable, and in that case you got nothing to worry about and just got to try and get over it and try to smile more. You'll probably get alot of good comments about your smile if you smiled more often.