My dad was an orthodontist, and he said a lot of problems orginate from pacifiers which cause baby teeth to "go buck". As the baby teeth fall out, the permanent teeth come in crooked too.
Just a simple $5 item can later result in thousands of dollars in corrective orthodontics.
Use a NUK orthodontic pacifier. It looks like this:
Don't use the pacifiers that are shaped like a light bulb.