vbo update

I would like fast rendering and I am trying VBO but the problem is that I need to change the vertex data with some smooth algorithms and others
that can change the topology of my object varying the number faces and vertex.
This is did sometime when user use a specific plugin and modify the object. Object maybe 300k 400k triangles.
Can I use vbo for it? Alternative?

Thanks in advance.

There are many effective solutions for buffer object streaming. Pick one.