You could, in PPT, hide the slides that you don't want to show in the side bar. Just leaving your "Topic" slides un-hidden will, as best as possible, create Topic options in the side bar.
But, I'm afraid that is the best answer.
For what it's worth guys,
If you have Presenter 6, you could always make an adjustment to the slide title by using the Slide Property editor in Presenter. If you open the editor, you can rename your slide titles independently and create a "chapterization" of slides that looks like they've been indented in the outline panel after the presentation is published. I have an example of this here:
Although Jorma's suggestion of hiding slides is certainly an acceptible approach, there IS one artifact of taking that approach and you'll have to account for it accordingly. Namely, hidden slides can cause completion conflicts IF your content is deployed on an LMS. What I mean by this is that if your content is set to report slide views, hidden slides are technically still part of that slide count. If your learner opts to skip hidden slides (or simply doesn't get to them if not specifically navigated to them), the LMS will always throw an "incomplete". Now there are a number of ways to overcome/circumvent that problem, but it would require a much longer response here.
I don't yet own P7, but there have been a number of folks who have complained that the above solution won't work in that environment. What I'd propose to potentially overcome that problem in P7 is to see if adding blank spaces before the title text on the actual slide will work. Either that, OR you could edit the viewer.xml file and update the slide titles there. The only real nasty artifact of that approach is that if you have to republish your work, you'd be forced to update your viewer.xml doc over again, and that's a pain for sure!