Plane Crashes and Investigations

I watched a show on the TWA 800(?) plane crash and the total reconstrucion of the plane that took place during the investigation. It was pretty clear that such a thorough reconstruction took place after every air accident.
However, in the 5 years since 9/11 I have never heard of any results or even an investigation of this type on the planes involved. Am I to assume that for the first, second, third, and fourth time in the history of aviation, a plane has vaporized to dust upon impact? Is this even feasible?

Can someone who believes in the Arab terrorist theory please explain why there was no investigation and reconstruction of the planes?

[edit on 7-9-2006 by TheComte]

This is a good question, especially for Flight 93.

For Flight 77, I can see how an excuse can be made on account of the plane allegedly being vaporized.

For flights 11 and 175, parts of planes were photographed, ie the ones that emerged from the buildings during the impacts, but the majority of the masses must have been utterly destroyed during the collapses. Everything else, besides the steel, was destroyed during the collapses. I have heard a firefighter attest to finding no non-steel debris bigger than part of a key pad for a telephone. Some 1000 people vanished in the collapses, with not so much as a finger ever found or identified. There was total and utter destruction of most everything in those buildings during the collapses.