Well in the beginning of this year-around January, I was really sick and I fainted and fell on the floor. My front tooh hit against the floor and died because of trauma and sometime around feb I had my root canal done. I had permanent retainers on, so those had to be removed. My dentist didn't complete my root canal treatment (the permanent filling) because after that I noticed my front tooth was darkening a bit.
So in mid-march I started a internal bleaching treatment. I was made a tray and told to put the gel on that tooth on the tray and wear it every night. I had a temporairly filling in my rooth canal tooth at this point.
It took A lot of time to whiten my tooth. In fact, I haven't even gone back for a follow-up (actually I missed my appt but she had told me she wanted to see me when the gel would get over-the gel was still there)
Now the thing is- I'm still doing my internal bleaching treatment. My tooth shade is not matching the rest. I have very little gel left and probably sometime at the end of this week will I go and visit her. I have been doing my internal bleaching treatment since 3 months. She said my tooth was strong and it was only the nerve that died inside because I didn't have a really bad fall.
I don't know what to do. My tooth is not even whitening.. it looks OK but it sometimes can be gray and I have no clue what to do. I'm really upset about all of this.. I really wish I didn't have to fall sick. My friend told me that my root canal tooth is transparent. But my mom says there is 90% improvement in the dark shade.
How long will the new shade last?What should I do about my whitening problem?

Great questions for your dentist who you should have been going to see and not waiting at home. It is possible that the gel will not do it, the dentist has other options that you need to discuss with them.

I recently had the pleasure of a root canal and during my treatment I overheard another endodontist discussing front teeth.

He said that is was very difficult to match color on teeth and it is very apparent on the front teeth. Even if you do match the color, it may change over time. Eventually, you could consider a visit to a specialist in cosmetic dentistry.

You are probably very sensitive to the difference in your teeth color. Most people may not even notice the tooth that is a different shade than the other teeth. For now, I would be patient, listen to the dentist, and take care of the tooth. When everything has settled down, you can worry about the color of the tooth. Otherwise you are talking about an extraction and a fake tooth and you really don't want to take that option.

Ask your dentist to see if she/he can bleach the tooth from inside.

The gel you are using isn't really meant to change the colour of a root canalled tooth. The dentist will have to remove the plastic filling material she/he put inside the root and place a bleaching agent. This may have to be repeated a few times until it matches the teeth on either side of the tooth that had the root canal.

The permanent way to whiten the tooth is with a veneer or a crown.