Most orthodontic problems are inherited. Examples of these genetic problems are crowding, spacing, protrusion, extra or missing teeth and some jaw growth problems. Other malocclusions are acquired. In other words, they develop over time. They can be caused by thumb or finger sucking, mouth breathing, dental, disease, abnormal swallowing, poor nutrituion, or some medical problems. Sometimes, an inherited malocclusion is complicated by an acquired problem. But, whatever the cause, an orthodontist is usually able to treat most conditions successfully.