Crowding results in rotated or overlapping teeth and is among the most commonly treated orthodontic problems. It occurs when there is insufficient room for the teeth to erupt, caused by a discrepancy between the size of the teeth and the available space in the jaw. Crowding can lead to uneven tooth wear and can make teeth difficult to clean, leading to an increased risk of decay and gum disease.

Spacing is when gaps appear between teeth. Like crowding, it is caused by a disharmony between the size of the teeth and the available space in the jaw. Spacing may also be the result of missing teeth and is often an unwanted cosmetic issue.

Excess overjet occurs when the upper front teeth are substantially further forward than the lower front teeth. This condition is often due to a discrepancy between the position of the upper and lower jaw, but can also be caused by thumb sucking. Protruded teeth can be unattractive and are at increased risk of accidental damage. This condition may also make biting into food difficult and cause speech problems.

An under bite occurs when the lower front teeth extend beyond the upper front teeth. The facial profile frequently appears unbalanced as the lower jaw is positioned in front to the upper jaw causing the chin to protrude outward. An under bite can also cause chewing difficulties, uneven front tooth wear, and jaw joint problems.

A deep bite occurs when the upper front teeth extend over most or all of the lower front teeth. In extreme cases, the lower front teeth may even bite into the roof of the mouth. A deep bite can cause excessive wear of the front teeth and can also damage the gum tissue behind the upper front teeth.

An open bite occurs when the upper and lower front teeth do not touch. This can make biting and chewing difficult, and can lead to speech problems. Open bites can be caused by habits such as thumb sucking or tongue thrusts. They may also be genetic in origin.

The upper teeth should fit outside the lower teeth in the same way that a lid fits on a box. A cross bite occurs when the upper teeth are incorrectly positioned inside the lower teeth. This is most often caused by a narrow upper jaw, and less frequently, by an abnormally wide lower jaw. A cross bite can lead to asymmetrical jaw growth, premature tooth wear, and jaw joint problems.

Missing teeth can result in a less than ideal smile with spaces or gaps between the remaining teeth. These open spaces can allow opposing and adjacent teeth to drift, leading to chewing difficulties and other problems with the bite. Treatment for missing teeth can involve either closing the space or creating the appropriate space for prosthetic replacements.

Prolonged or persistent thumb (or finger) sucking can produce an unattractive smile and can result in various malocclusions including an open bite, cross bite, and protruded front teeth. An open bite can result because the position of the thumb prevents the upper and lower front teeth from erupting. Thumb sucking habits can lead to a narrowing of the palate, which in turn can cause a cross bite. Finally, repeated positioning of the thumb behind the front teeth can lead to protrusion of the front