I took of my braces on dec 2012. my last tooth, 2nd molar had decay. i don't want to do a root canal. if i extract it, will it affect anything?

Save your tooth.: Inspite of all you have heard about root canals, they are not bad at all. It is better to save this tooth of you can. Teeth can shift when one is removed. One option that you mat want to talk to your orthodontist about is to move the wisdom tooth into the position of your second molar. Sometimes that can be done. Good luck.

Yes: You will lose around 5-6% of chewing efficiency by having it extracted. You may not even notice it. Depending on the extent of the decay it might be best long term to have it extracted and if you notice decreased chewing efficiency you can look into replacing the tooth with a dental implant in the future.

Yes: You will loose some chewing efficiency. I would recommend that you keep the tooth especially since you are so young. If you have it removed replacing it with an implant may not be possible depending on your sinus anatomy (how much bone is available) and the bone in the back portion of the upper jaw is not always dense enough for an implant.

Yes: Removing the tooth will allow opposing molar to over-erupt, which may cause functional interferences. Sounds like you need to see an endodontist.

Yes: You spent all this time and money to have orthodontics and now you are thinking about extraction rather than a root canal? Makes no sense! see an endodontist, your root canal wii be un eventful.