Piezo Electric units enable us to utilize ultrasonic energy in handpieces which convey high energy to very fine cutting tips of various shapes and sizes.  Unlike traditional rotary handpieces, which by comparison are much larger and uniform in shape, the ultrasonic tips are able to  access the smallest of working areas, thereby allowing us to treat problems in very inaccessible places. They are especially necessary during endodontic surgery, during which we must make very small preparations within the very tip  of a root.  Rotary handpieces never had the ability to adequately perform this function.  Lastly, ultrasonic energy is also utilized to remove posts or other obstructions within the root canal.  Our attempts to save a tooth may very often come down to this very ability.