What is the best way to diagnose a cracked tooth?

One of the best diagnostic aids for determining if a tooth is cracked or not is a stick or wedge-shaped instrument that the patient can bite on to wedge the cusps apart. This will elicit pain in a cracked tooth. One new product that is very useful for this is called the e-Dx (Jordco, Inc.). It is a plastic instrument with a wedge-shaped end for bite testing and an end with pliers to hold a foam insert for cold testing. Refrigerant can be sprayed on the foam and placed directly on the tooth to test for cold sensitivity. This tool is an easy way to test for both reversible pulpitis and cracked teeth.