Asian nose bridge material: What would be the best option? (photo)

You have facing a very common situation where you are replacing a silicone implant with diced cartilage fascia.  I favor utilizing DC-F as this provides a more natural shape in the long term vs silicone implant and also minimizes your chances of an implant infection which can occur anytime during the lifetime of the implant.  Although it is true that you can get enough cartilage from the septum and the ear to fill the DC-F, Asian patients tend to have very little septal cartilage which may not be enough to fashion support grafts as well as enough diced cartilage for the DC-F construct.  
There are cadaver rib cartilage pieces that can be used as an alternative if you are very much against utilizing your own rib cartilage.

Using tissue from your own body will create the most permanent results in the safest manner.  The biggest risk with silicone implant long-term is the risk of extrusion through the skin.  Since Silicone is a synthetic material it will never become incorporated as a living part of the nose as your own cartilage will.   A rhinoplasty specialist experienced in autologous grafts will be able to precisely and safely augment your nose using only tissue from your own body. @asianrhinoplasty

Removing the silicone and repalcing it with autogenous rib cartilage is a common practice. Revision is better done with autogenous material and using silicone agin is not a good choice. In Asian, septum and ear cartilage does not afford enough material for dorsal augmentation. 
Megarderm will resorb slowly, and it will lose considerable amounf of volume in 1-2 years. Using diced cartilage or intact cartilage is decided considering many factors. Even with dicec cartilage, tip is done separately from the dorsal augmentation, so you need separate grafts on the tip.