How long before my tooth falls out? (Photo)

It appears you have receding gum tissue with your lower front teeth probably due to thin biotype of your gum tissue which is more prone to such condition. I suggest a consultation with a periodontist to discuss possible gum tissue graft to create a thicker and more resilient gum tissue. Splinting also may be beneficial. With good diagnosis and treatment, such teeth can be maintained healthy for many years.

You should make sure your dentist checks your bite to ensure you are not hitting that particular tooth more heavily than the rest. You want to make sure you are wearing an orthodontic retainer. You might also consider the "pinhole surgical technique" to improve the gum recession.Good luck!

There is
some recession on that tooth but periapical x-rays and pocket depths are also
used to evaluate teeth. If you are really concerned, you could always see a
periodontist (gum specialist) for an evaluation.

It is common for front teeth to begin to shift and crowd beginning around age 20 years.  You may want to consider a bonded retainer wire to prevent teeth from shifting.  Also, the gum recession that I see in this photo is mild and you would likely get the same advice in my office.  However, you can certainly take a more proactive approach by removing the tight frenum attachment (that piece of tissue holding your lower lip to your gums).  In my office this is a minor procedure done with a laser.  You could even have a small gum graft to bolster the amount of gum tissue around the tooth in question.  Your dentist is correct that oral hygiene is critical to keeping a healthy mouth.  A healthy diet and healthy habits are just as important.