What's the best temporary solution for filling in a gap between my upper canine tooth and the first premolar? (photo)

Based on your photos and the fact that your wedding is coming up, I would highly recommend getting dental bonding on several of the teeth in the photograph.  It would really do a lot for your smile.  The main problem with dental bonding on anterior teeth is that it easily stains, so it should always be considered temporary.  If you have a wedding coming up in July, bonding can provide that temporary appearance to of cosmetically perfect teeth.  If you are looking for a permanent result, you should get porcelain veneers.  Veneers last about 30 years when done properly and proper oral hygiene is maintained, but can be more costly, depending on the region of the country you live in.   Good luck and I hope this helps. Follow me if you have more questions.Sarah Thompson, DMD

Certainly bonding can be done.  However, it depends on how the lower tooth fits against your upper space to a large degree.  It is a pretty large space for bonding, and your two teeth will look larger than normal.  As a temporary fix the bonding should be Okay, but the orthodontics is the best solution to correcting that problem, with porcelain veneering another choice to consider.