I think that teethers are mainly used for comfort. Dirk, my oldest, never used a teether. He wasn't interested in them.
There are many options outside of traditional teethers found out Walmart, Target, Kmart, and etc.
There are teething tablets:
http://www.hylands.com/products/teething.phpHazel wood necklances that are supposed to be good for colic also:
http://www.purnoisetier.com/Teething amber necklaces:
If you are breastfeeding you can make "momsicles" that would feel good on a teething baby's gums. Cold vegies when your baby is old may also feel good.
For directions:
http://www.mother-2-mother.com/momsicles.htm