Hello sir, It may be a cavity or stain. Just take a treatment for this as soon you can. Visit a good dentist and rule out the problem.

Yes, as u saying its since  2 years.Obviously that may be a cavity.Get it restored by any dentist.Othewise it may create more problem.

It should be a just small cavity.. It's been there now for 2yrs,dont delay much.. Just consult your dentist.. A tooth colored filling will do if there is NO pain.

Please visit your dentist..could be a cavity or just a stain. Treatment will depend accordingly.

The way you have clicked the photograph makes it difficult to read..... whenever you shoot a radiograph, it has to be done perpendicular to the film and without a flash, against decent light..... a reasonable opinion cannot be given based on the picture that you have posted..... what was the opinion given to you by the dentist who took the X-ray????? to the best of my understanding based on the picture that you have shared, I don't see a cavity in the tooth, but if you are talking about the black spot near the roots, this could be the maxillary sinus or any cystic pathology..... but these are tentative opinions.... go for an x-ray called OPG for the best valuation of the case.... Regards.....

I am not sure there is a cavity as the x ray is not clear but if u doubt for a cavity , u may visit a dentist nearby, and get a tooth colored filling done.

That spot can be a cavity. Get it filled as soon as possible. Get a check up done