The Habit by MED et al. Thumbsucking is a normal activity among children. It can be necessary for normal physiological and psychological growth.
Babies use sucking to get food, explore the world, and have pleasurable oral sensations.
Babies also learn to associate it with closeness and tenderness. As children develop, they learn new ways to explore and get emotional fulfillment. Thumb and finger sucking should be eliminated before appearance of damage to the terminal plane. Since the terminal plane begins to change at four years of age, the age of cessation should be three to four years. The elimination age of thumb and finger sucking is a most important factor.