Trees vs. Tables

[Syl X]

Good Day All !

I haven't really had any experience with Trees.  And, I've got a
problem that I see can be tackled in either one of two ways - using
Trees or Tables in the DB.

Here's the problem:  I've got a threaded list, but it can only go two
deep.  Here's what it looks like :

--> AD 1
------> Question 1
-----------> Answer 1
-----------> Answer 2
------> Question 2
--> AD 2
--> AD 3

Essentially, people either ask a question or respond to a question.
And, that's as far as it goes.  I've implemented it using Threads, and
I'm querying the DB with findAllThreaded().

I'm looking for some advice from those of you who've worked with this
kind of thing more.  Would it be wiser/more efficient/easier to
implement this using a three table model ?
1) ADs
2) Questions
3) Answers

When I display them, the appropriate Ads, Questions, and Answers must
be visually connected.

Here is some extra info..... both questions and answers have only 3
fields in common with the 15 fields in my ADs table.  I've been sitting
on the fence on this one.

Thoughts anyone ?
Thanks all !

Syl