Both the PLDD and PODT methods are used to treat herniated discs, but their mechanism of action is different. The PLDD method reduces internal disc pressure by ablation and vaporization of a small amount of tissue from the nucleus pulposus, while the PODT method shrinks the disc by oxidizing the nucleus pulposus with ozone. The PODT method is also expected to be effective for spinal canal stenosis and degenerative disc disease.