A diastema is a space or gap between two teeth. It appears most often between the two upper front teeth. However, gaps can occur between any two teeth.

A mismatch between the size of the jaw bones and the size of the teeth can cause either extra space between teeth or crowding of teeth. If the teeth are too small for the jaw bone, spaces between the teeth will occur. If the teeth are too big for the jaw, teeth will be crowded.

Spaces develop for a few other reasons as well.

Sometimes some teeth are missing or undersized. This happens most often with the upper lateral incisors (the teeth next to the two upper front teeth). That can cause the upper central incisors to develop a space.

A diastema also can be caused by an oversized labial frenum. The labial frenum is the piece of tissue that normally extends from the inside of your upper lip to the gum just above your two upper front teeth. In some situations, the labial frenum continues to grow and passes between the two front teeth. If this happens, it blocks the natural closing of the space between these teeth.

Habits can also lead to gaps between the teeth. Thumb sucking tends to pull the front teeth forward, creating gaps.

Spaces can develop from an incorrect swallowing reflex. For most people, the tongue presses against the roof of the mouth (palate) during swallowing. Some people develop a different reflex known as a tongue thrust. When they swallow, the tongue presses against the front teeth. Over time the pressure will push the front teeth forward. This can cause spaces to develop.

Periodontal (gum) disease results in the loss of the bone that supports the teeth. In people who have lost a lot of bone, the teeth can become loose. This movement can result in gaps between the front teeth.

Children may have temporary gaps as their baby teeth fall out. Most of these spaces close as the permanent teeth reach their final positions.