What is the highest density you can achieve with multiple transplants? As an example, if I lost all the hair on my crown could I have it replaced to what it was before? Or to match the native density of what's left on my head?
The highest density possible will depend on the skill level of the surgeon and would need to be a progressive, multi-session approach. In all honesty, it is not something that is necessary and 45-50 grafts per/cm is enough to give the appearance of fullness. Balding only becomes apparent when you hit 50% loss on average and the average density before miniaturisation is usually around 80-90. This is why 45-50 is optimal as it reaches the goal without using up excessive grafts from a finite donor. Yes, if your donor is way above the 8000 average for FUE then in theory you can have multiple procedures building up to 70 in theory. But it's not necessary for a good result, it just takes it to another level for those who have significantly higher than average donor capacities. It all needs to be planned with the surgeon.
That makes sense. One other question. If the native hair behind the transplanted hairline is around 80 or 90 per cm how does the new hairline at 40 or 50 look or blend in? Will it make the hairline look thinner?