Tyga -- Drops 45 Racks on New Grill (VIDEO)

Tyga's just got a new jewelry store ... in his mouth. Celeb jeweler Ben Baller just hooked Tyga up with the chompers ... dripping in 1400 diamonds. At $45,000 and 18 carats ... it's the most expensive grill Baller's ever made. On the other hand ...…