The symptoms for a cracked tooth can be pain on chewing (especially grainy food) or on releasing the biting pressure. Cold or hot food can cause discomfort as can sweet foods. A crack may not be visible to the eye or even on an x-ray and pinpointing the problem tooth can be problematic for you. Clenching or grinding can cause a crack to appear due to the pressure exerted but a tooth that has been extensively filled can over time crack. We keep our teeth for longer now and simple wear and tear can also see the crack begin and slowly work down the length of the tooth.