Pain is not the only symptom to alert you that there may be a need for dental treatment. Crowns are used to provide strength and stability; sometimes a crown is the only effective restoration for a large cavity or weakened tooth structure. Frequently, teeth that have large silver fillings for decades begin to crack around the filling. Dentists can detect this breakdown before it becomes noticeable to you and diagnose the tooth for treatment. Cracks are a concern because the cracks allow a path for bacteria to enter the tooth and make the tooth susceptible to fracture. Depending on the situation a new filling or crown will be recommended.