Teeth... hehe

The only thing with teeth in your forward gears would be the planetary gear set.
But if that went bad most gears wouldn't work.

Easiest way to do some testing would be looking at line pressures while going through the gears and comparing with OEM specs or pull off the valve body and try to engage the clutch packs with an air gun.

Since most manufacturers dont rebuild transmission anymore you are most likely looking at getting another trans or looking a huge bill from a trans shop to do a rebuild. Rebuilding an auto yourself for the first time can be a task and half the time buying a reman will be cheaper anyway.

good luck