Creases can be hard to repair with PDR:
https://www.impactdentrepair.com/3-t...emoved-by-pdr/
THE 3 TYPES OF DENTS YOU COMMONLY SEE
Car Dings – These types of dents are more common because they tend to be caused by smaller objects or pokes, and are usually easy to repair as long as no damage to the vehicles paint has occurred.
Round Dents – This type of dent can be caused from hailstones or a similarly round object (football, baseball, basketball, etc.) hitting the car and causing a dimple on the door, bumper, roof or hood.
Crease Type Dents – Crease dents usually bends and tears the car’s metal. When a vehicle is being produced, the car has its own metal memory formed; this is done by heating the metal and shaping it to the design required. When an automobile acquires a crease type dent, it is possible to lose the metal memory making it hard to repair back to original shape.
With Paintless Dent Repair (PDR) most non-collision dents, like the ding and round dents can be repaired.