Why do I always have smile lines? Is over jet teeth the cause? Can it be fixed? (Photo)

Pls pardon my English and lack of knowledge. I'm 19 years old. I almost always have these lines around my mouth. Like smile lines. I don't know how to describe this, but my mouth almost kind of bulges forward. I look terrible. I always look like I've food in my mouth or something. What condition can be the cause? Over jet teeth? Uneven teeth? Gum related problem? Can it be fixed? How much will it cost me?

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