Hi,
My first child never used anything at all. My second daughter was VERY fussy for the first three months so I reluctantly offered a pacifier, but only at bedtimes until around twelve months when she had to have a surgery and needed it for comfort. My third loves his pacifier and unfortunately uses it ALL of the time. Babies suck for comfort it's one of their first reflexes, so most likely he's not hungry just self comforting which is a good thing. My pediatrician said not to worry about problems with their teeth until around 1.5.
Amazing story, like I said my second was OBSESSED with her baba after a year old and her teeth were a mess at age two, pointing many different directions (I was very upset about the whole thing, as I swore that none of my children would ever have one of those things hanging out of their mouths all of the time) ha! Famous last words. When she was two she and her older sis were running around and kind of crashed into each other. Needless to say, my two year old ended up getting stitches in her lower lip, due to upper teeth biting through the lower lip. The ER doc put three extra stitches in her lip begrudgingly due to pacifier use. Well, we just never offered it again and fortunately she asked for it only a couple of times, but the miraculous thing was within two months of this incident her teeth began to straighten out and now two and a half years later it's not even an issue, she's got nice (mostly straight) teeth. One bit of advice if you can get your baby to take a pacifier it's MUCH easier to take that away then get him to stop sucking thumb. My sis sucked her two fingers until she was NINE!!!! My husband says we're going to stop letting our little boy use the binky around one, but I don't think we're going to be able to do that, he's SO attached to it, it's almost like a blanky. Whatever you do, good luck.