Some users of extenders have reported some improvement (expressed in % ) of curvature. Nothing posted recently comes to mind.
Figure out some way to measure your curvature & record it, for a starting reference.
This is touted as a benefit on sales pages but I have yet to come across a success report that an extender can fix a curvature. Though I haven't made it a priority to search.
I have a slight curve to the left (I thought it's because I use the right hand to :wankrobably genetic though) so I will be reporting if this curve corrects itself over time in my progress thread. Should be an interesting thing to see if it does.