According to US Baby experts:

Using a soothing pacifier in the right time will not induce fetishism. Blindly prohibit a baby from using the soothing pacifier will impact their physical and mental development, thus resulting in pessimism and wincing behavior. If your baby gets used to sucking fingers at the oral stage, the bacteria in fingers are prone to influence the development of upper and lower jaws, even the shape of finger, skin and nail will deform due to long-term sucking.