Is there something I can have done to fix this "dent" on my jaw line, left after the removal of an abcess? (Photo)

YES! Try HA fillers or fat grafting options. Might take many syringes or fat graft sessions to obtain a great result....

Sometimes filler products may do the trick to improve your dent(?).  Best to be seen in person to be properly evaluated.

Yes, I would recommend trying a Hyaluronic Acid filler in the area to fill the dent in, such as Juvederm, Restylane, Voluma etc. These are non-permanent fillers, which will give you a very nice results. These are also reversible if you do not like the result. You could also try a semi-permanent filler such as Radiesse to the area which will stimulate collagen production. I would recommend using a HA filler first to see if you like the result before advancing to something like Radiesse. Make sure you go to a board certified dermatologist or Plastic Surgeon who is experienced in injections.  

I  have had very good success with Fillers. They do require more than one treatment, but produce very natural results.

Hi.  The white bump based on these photos (which are not very clear) appears to be a "standing cone" also known as a "dog ear."  You can google those terms to learn more.  As far as the dent, it can be easily filled with Juvederm Ultra Plus or Voluma.  Fat injections are also an option.  

The dent can be filled with dermal fillers or with fat grafts depending on its depth and location. Don't worry it can be fixed! See a board certified plastic surgeon to help you.