Crowded teeth, the opposite of spacing, is caused when there just isn't enough space in the mouth for all those teeth. Crowding just gets worse over time as one tooth pushes over the other, leading to overlapping teeth. Crowded teeth are harder to clean then straight teeth, which will lead to cavities and tooth decay. Crowding can often be corrected by expansion so as to avoid tooth removal.
In an underbite, the lower jaw is longer than the upper which causes the lower teeth to protrude in front of the upper teeth. It is best to diagnose the problem early.
An overbite, or deep bite is when the front teeth cover the lower teeth too much. An excessive overbite leads to wearing down of the teeth and even may cause the bottom teeth to bite into the roof of the mouth.
A cross bite is when the upper back teeth erupt and function inside or outside the arch of the lower teeth or when the lower front teeth erupt and function in front of the upper front teeth. A cross bite can be individual teeth or a group of teeth.
When the upper front teeth stick out too far forward, or the lower teeth don't extend enough, this is called protrusion. Because of the abnormal contact between the upper and lower front teeth, it could cause injury to the lower teeth. It also causes poor bites and may even be from uneven jaw growth. This problem can be caused by thumb and finger sucking.
Mid Lines Off
In a perfectly aligned face, there should be a straight line from the bridge of the nose to the bottom teeth...all should be lined up. If they are not and the bottom teeth are actually misaligned from the top teeth, then your midlines are off. When your midlines are off your teeth could be drifted or your lower jaw could be shifted, which would result in an improper bite.
The common result of thumb sucking or tongue thrusting, an open bite is when you can actually stick your tongue between your teeth while biting down.