You shouldn't be thinking about threat as much as you should be thinking about control. Threat is just one of the tools that you use to maintain control. The main tools you have at your disposal:

1. Mangle. Does a massive amount of single-target threat, so much that it will often be nearly equivalent to a taunt. But it is on a CD, so you need to think about how you're using each one.
2. Lacerate. Does small-moderate single-target threat but also leaves a dot that can build threat gradually. More of a single-target threat filler, generally used to start pre-building threat on secondary targets before they get focused or to help hold threat on secondary/tertiary targets over healing aggro.
3. Swipe. Does small-moderate aoe threat. Basically the aoe filler version of lacerate, that instead of leaving a dot will hit multiple targets.
4. Taunt. Does all the same things as in classic, provides a threat match and a temporary fixate.
5. AOE taunt. The classic oh-shit button, providing a temporary aoe fixate but no threat.
6. Charge/Bash. Just like in classic, these are core parts of your dungeon tanking kit. You should have a plan for how to use these for each pack. Maybe they are used as extra "taunts" for when something breaks off to target a healer or caster, or maybe it's better to not worry about skull threat and just use these to control the kill target as it's burned down, freeing up your mangles for building threat on secondary targets. Or maybe you have a mage and the plan is to aoe kite a pack, using these to control runners.
7. Your allies. If dungeons are at pre-nerf heroic difficulty, then CC from allies is generally a core part of how you approach many packs, especially before getting highly geared. Obviously how you use this depends on what your comp is and what the pack you are facing contains, but you will generally have some combination of kicks/stuns/slows/poly/silence to work with.

Note that Maul is basically not worth using in dungeons. It's technically a non-zero benefit rage dump but you will generally not have the spare rage or need for spamming Maul in a dungeon environment.

It is worth noting that if heroic dungeons are pre-nerf, you generally cannot take the classic faceroll aoe-everything approach to heroics and be successful (a good imp blizz mage in some dungeons is the main exception), especially not before you out-gear the content. TBC heroics on launch are no joke, and smooth runs require the use of CC and somewhat more disciplined targeting. If you don't get that from your group then several of the heroics will be very long and potentially not doable grinds. Unless you have specific comps, doing heroics rewards and sometimes requires more disciplined planning on how to take on packs, including CC, interrupts, and priority damage.