Many surgeons say that they use silicone for dorsum and autograft or Alloderm for nasal tip. But what they do is not the standard nasal tip surgery.

Most surgeons do nasal surgery like the picture putting a small piece of cartilage at the end of the silicone implant.

But the standard nasal tip surgery means that the silicone implant doesn't reach near nasal tip area.
In the right picture you can see the nasal surgery that used soft Gore-tex for dorsum and autograft for the tip. As you can see Gore-tex doesn't reach nasal tip part. Even though Gore-tex is safer than silicone autograft must be used for nasal tip.