At Paul R. Downing, DMD, PC, our team often recommends a dental filling to repair damage to you tooth caused by decay. Frequently referred to as a cavity, this decay can be extremely difficult to detect in its early stages. For example, a dental probe often cannot access the area where a cavity is growing, and this type of cavity cannot be detected by an X-ray. To further complicate the situation, forming cavities typically cannot be seen by the naked eye.