I was bottle fed and used a nuk type nipple. I would turn this Orthodontic nipple upside down every time. To spite my mother continuously turning it over. I was also given the nuk pacifier and would only suck in the flipped backwards position. As I grew you could see the effects. Bugs bunny had nothing on me! I wore braces (not the usual but ones that banded each tooth completely....industrial strength!) for 5 1/2 years. The teeth are straight and I am very thankful. Now, we joke about the money she could have saved from Formula, Dr. Visits (I was always ill) and Braces she could have taken two trips around the world. Michelle Ramsey