Hi L.,
My little girl is now 5 so I am a little out of that loop, but the one thing that I do remember is that it seems twice as hard to break them of anything; bottle, binki, finger sucking, sleeping with you or in the same room, etc. after 9mths. I would do what ever you feel is best for your child and what you are willing to take the risk of enduring or not willing to endure.
I do know that frozen or cold toys seems to help sooth gums. Maybe you should give the little guy a couple of things and see if he chooses. Change them up a few times and see if he always goes back to the same one. Experiment!
My little girl never "used" a binki, only played with it, until she had a few abrupt changes at about 18mts. At that point she quickly became addicted, on account of compfort. Then she added a thumb. The type of binki she had did affect her teeth, but not too badly. And even now, if she had a binki she would take it. She wouldn't care who was lookin! And she sucks her thumb. She would even do that all of the time if we would let her.
My friends little girl is the same age and sucks her thumb when ever she wants. She doesn't seem to want to do it at school so she chews up her shirt sleeves instead! Arg!...And who said parenting was easy anyway?!?! Good luck.
Happy Parenting!
T.