While a dent is unlikely of itself to cause a scratch, any deformation can trap hard dust or grit particles. These hard particles, if present may indeed cause screen damage.
It is generally recommended that you change the Pencil tip as soon as there is visible wear or damage. The Pencil tip is a consumable part that should be regularly changed. The cost of a replacement Pencil tip is negligible when compared with the very high cost of replacing an iPad screen.
Replacement Pencil tips are available from Apple in packs of four:
- Apple Pencil Tips - 4 pack
https://store.apple.com/uk/xc/product/MLUN2ZM/A
Be aware that dropping your Pencil onto its tip risks unseen damage to the transducer element that sits immediately beneath the replaceable Pencil tip. If this is damaged, the Pencil may not work reliably, if at all.