I can't bite with my front teeth. They don't seem to touch each other.

The type of bite you referred to is called an open bite, meaning that your upper and lower front teeth do not touch when biting down. All the chewing pressure is then placed on the back teeth and this excessive biting pressure and rubbing of the back teeth may make chewing less efficient and contribute to significant tooth wear. Many people have this problem without noticing it, whereas others elect to correct their open bite, so as to save their back teeth from excessive wearing.