Talk to Pediatrician on Sucking Finger

Salam, my 3 year old daughter sucks knuckles of her right hand index finger . Her habit is since she has born. During pregnancy Once my doctor also told me during ultrasound that she is sucking finger. She sucks her finger alot when she is sleeping. I try to take her finger out of her mouth she starts crying. I also tried to put saniplast on that specific finger but that also fails she wakeup take it off and start sucking again. Due to this habit her front teeth are of not same size means they r small as compare to other teeths. And secondly her finger skin is damaged badly. Please doctor can u advise how to get rid off this habit. Thanks in advance