When we first tried the regular nipple, I just took out the rubber nipples that came with the small evenflo bottles we have.  The problem with those was that the formula was coming so fast that she was filling up before she realized she was full.  When her stomach was overfull, everything she had eaten came right back up!  So, we started limiting her feedings to 4 ounces and feeding her more often.

Next, I picked up some slow-flow regular silicone Gerber nipples at the grocery store.   These seemed to work quite well for a few days.  For the bedtime feedings (when she seemed more likely to spit up), I continued to use the rubber orthodontic nipple. 

Late in the week, though, Rebekah started to refuse to drink from these new nipples.   When I switched back to the orthodontic nipple, she seemed to drink better than ever before.  Looking back, I'm not sure if she doesn't like silicone nipples, if she doesn't like the normal nipple, or if she was just so tired that anything different than she was really used to made her excessively fussy.  Time will tell.