What do results of a dental transillumination test mean?

Possible fractures. Often transillumination is used to diagnose internal fractures or cracks internal in a tooth. X-rays only are a two dimensional view and are of little diagnostic help for stress fractures. Other symptoms such as sensitivity while chewing can help confirm a fracture.
Tooth defects. Dental transillumination test highlights the defects that are not easily seen inside the tooth.The results help the dentist do a better job in treating the patient.