Babies use sucking to calm and settle themselves.
Children usually give up thumb-sucking when they develop other ways to calm down and comfort themselves, usually by age 4 to 5, although many children suck their thumbs at night or occasionally, when stresses become too much, for many years beyond that. It's unlikely that your child will continue sucking her pacifier well into the childhood years when it might threaten proper dental development. You're unlikely to be successful, and it will only lead to unnecessary struggles and frustration for both of you. If you decide to restrict her access to a pacifier, help her find her thumb, or offer her a blanket or a soft toy to comfort herself instead. As with any source of medical or health care information, you should as a preliminary matter satisfy yourself that the credentials and experience of the source are suitable.