Thumbsucking

Right this very moment, the baby princess is thumbsucking. She mastered this skill when she was about 2 months old. At first, it was a hit and miss thing. She'll start by looking at her hand, then slowly,deliberately the hand would come closer and closer to her mouth and shoot! Thumbsucking galore. Right now, she doesn't need to look any longer, she just puts it straight in. What do I do when she thumbsucks? Sometimes, I remove it, sometimes I just let her. I believe its a phase she has to go through and if it gives her comfort and lulls her to sleep, then well and good. There have been different opinions about thumbsucking and the most common reason used against it is that it will cause bad dentition or something. But many previous thumbsuckers, now full fledged adults would attest this to be not true at all! Some say that it would eventually cause speech problems but i also read that this is if thumbsucking persists until 5-6 yearsold. But its not really an issue for me, as I watch her fall asleep peacefully and contentedly.