Are Munchkin 360 cups bad for a baby's teeth or speech?

This is the category's biggest live disagreement. High-trust community threads (r/beyondthebump, r/NewParents) cite feeding and speech therapists who discourage the 360 because it can encourage chin-lifting and an atypical jaw motion, while other high-trust voices in r/Parenting and r/ScienceBasedParenting argue the open rim is actually better than a hard spout. The cup is wildly popular and effective at preventing spills; if oral development is your priority, straw cups are the more consensus-safe pick.