Your dentist needs to take an x-ray of your mouth to help with your care. There are many benefits associated with the use of x-rays, such as your dentist being able to see what their eyes cannot (such as inside your bodyto find hidden dental structures, malignant or benign masses, bone loss, and cavities). This is much safer than using invasive techniques such as surgery.
Dental x-rays are exceedingly safe, but like everything in life, there is a degree of risk involved – you will receive a negligible dose of radiation which carries a tiny (less than one in a million) chance of side effects. Furthermore, your dentist will never take an x-ray unless the benefit to you exceeds the minimal risk. To put this into context, this dose of radiation is so small that it will be equivalent to what you receive in a few days from natural background radiation that is present in the surrounding environment.