How can I get my buckteeth overbite fixed without braces?

Not easily. Orthodontic Care will put your teeth into place. If your overbite is mild, it may be possible to reshape your teeth, but not if you have a severe skeletal component...can't "straighten" teeth on jaws that don't match. Also know that braces require postRx retention. Restorations require periodic repair/replacement. See both Orthodontic Specialist & Cosmetic Dentist for consultations.
Overbite. In layman's terms, an "overbite" typically refers to the upper front teeth sticking out horizontally, further than the lower front teeth. Get an opinion from an orthodontic specialist regarding the best option (it depends highly on the severity of your own problem) as there are clear braces, invisible braces, or possibly clear aligners that may be options.
Cosmetic dentist. There are several cosmetic dental proceedures which canbe used to correct your "buckteethoverbite". The first step would be to get a consultation with a cosmetic dentist to go over your options.
Gererally. You cannot. I would suggest that you find an orthodontist who is accomplished in invisalign and or one who uses suresmile. Sursmile will decrease the treatment time by 1/3.