Will 1/2 a syringe of Juvederm affect my smile/cover my teeth at all? Is there anything I can take beforehand for pain? (Photo)

A bit of filler in your lips will make them appear fuller which will help to cover some of your teeth but it won't affect your smile. You have a gorgeous smile so it doesn't need any help. Once the filler wears off, the lips returns to their pre-injection size. Make sure to see an experienced injector. 

Your lips look nicely volumized.  Adding more volume will not help cover your gummy smile.  However if you desire larger lips, when Juvederm wears off, the natural elasticity of the lips will not be effected and there will be no long term issue with skin quality.  Some patients who are distressed by a gummy smile can have injected,  a carefully measured amount of Botox in strategically placed locations near the upper lip to slightly weaken it, hence less of a gummy smile and less lip elevation when smiling.  If too much is injected the lip becomes temporarily too lax, a very distressing complication.  The small amount injected will likely only last several months.  Many physicians will not wish to do this as a stand alone procedure given the short longevity and possible downsides.  See only a specialist to consider this treatment.