Hi there,
For an old skull injury which is stable, the dent or defect can be filled in using various methods, including autologous tissue (your own - e.g. fat / dermal / bone grafts) or non-autologous products (manufactured - e.g. calcium hydroxyapatite, hyaluronic acid fillers).
Each of these has it's pros and cons, and involve either minimally invasive approaches or open surgical approaches. The assessment of the most appropriate treatment method/s will also depend on the extent of the defect.
It would be best to get assessed by a plastic surgeon to discuss what's best for you.
Dr Adrian Ooi
Consultant Plastic Surgeon
Polaris Plastic & Reconstructive Surgery
Illumia Medical