A.J.
If it's not broke, don't fix it. ;) I think it is a little to early to worry about the teeth thing yet. If you are even brushing gums or teeth in the mornings that is enough for him at this age. I just think about the sleep problems that will come from this which are going to be way larger than teeth could be at this point. Sorry!
If it helps, my daughter has a little toothbrush that we keep in the bathtub and she loves to use it over her mouth in the tub at night before bed(kinda like a toy). I still give her a bottle at night(8 months now) and am going to start changing the daytime bottles to sippy cups soon. Then the bedtime bottle I will probably wein last more around one year or so, depending on how she acts.
Good luck :)