As the mom of a child who spent many, many years in speech therapy, I feel qualified to offer this tip: If your child can walk, limit pacifier use to bed only.
I see LOTS of toddlers walking around with pacifiers.
A pacifier is a great object for self-soothing, and many babies need to suck to relax themselves and soothe that instinct. However, a toddler should be replacing the pacifier with other self-soothing habits.
Walking around with a pacifier can inhibit speech, either because there is something in their mouth preventing them from speaking or because extended use of a pacifier can lock a child’s mouth into an unnatural position, making it more difficult for his tongue and mouth muscles to develop normally.
Pacifiers can also push against teeth, making them come in at an unnatural angle.
Some pediatricians recommend ridding baby of the pacifier all together by 18 months. I’ll readily admit that both of my boys used them until they were after 2, but only in bed, for naptimes and bedtimes after about 9 months. Also, our speech issues were not pacifier-related. Although, I talked to lots of moms in the speech language pathologists’ waiting room who did admit a pacifier contributed to their toddler’s speech issues.