Thumb sucking can lead to oral and jaw changes. The level of changes could differ according to the duration, intensity, the habit’s repetition throughout the day and night, and how the thumb is placed in the mouth. The most important changes caused by thumb sucking are as follows: Anterior Open Bite (no vertical overlap of the anterior teeth): When children press their teeth on top of each other, the anterior teeth don’t reach each other. The child will therefore have issues biting on an apple or a sandwich. Increased dental overjet and protrusion of maxillary anterior teeth: Increased horizontal distance between maxillary and mandibular anterior teeth and extreme outward sloping of the maxillary teeth Posterior Crossbite: The narrowing of the maxillary dental arch and incorrect overlap of the maxillary and mandibular incisors Overall, these changes reduce the effectiveness of teeth in chewing food, aesthetically degrade the child’s teeth and face, and cause diseases and temporomandibular problems over the long-term.