What are signs i need a root canal?

[honeybee91]

Hi can a dentist on here tell me what are symptoms I would need a root canal?

I had a nasty abscess a few years ago. The molar was super sensitive a few weeks before it showed up. I ask because I can't tell if this swollen gum is gingivitis or an abscess. It's near my bottom tooth. No pain at all. I have an appointment next month (no sooner avaibility) the gum is lighter there and that's what bothers me. Everywhere else is the normal gum color (minus my red swollen gums) it doesn't look like puss but what do I know. It doesn't look like the abscess I had before either, that one was quite large and red. I'm just a very anxious mess over this.

 

[Gordon]

If it's an acute abscess, then usually there will be pain on biting, pain on eating hot food that tends to linger, the tooth might be a bit loose in the socket and or feel a bit "high" compared to the others. Occasionally it'll "point" out through the boney plate above the root and you'll get a sort of zit on the gum.
Sometimes you get a chronic abscess where the tooth just feels a bit "off" but mostly shows up on x-rays.