Pacifiers are actually good for preventing SIDS "Sudden Infant Death Syndrome" Pacifiers are good for baby as long as you wean them off the pacifier before they get old enough for the pacifier to affect their teeth.
Once your child turns 2 years old you should start limiting the use of the pacifier and completely get rid of the pacifier by age 4 as once they get to 4 and beyond it can affect the child's teeth.