Why don’t my lips close naturally? I had braces for about 4 years. (Photos)

This is best assessed by your dentist or orthodontist. Fillers can be used to improve your lip symmetry. Hope this helps. 

I recommend following up with your dentist. However, fillers (Volbella, Restylane, Juvederm) can be used to improve the symmetry and shape of your lips. Nova threads can be used to improve lift and shape. Implants or fat are alternatives. See an expert. Best, Dr. Emer

Thanks for your question. This is a good question for you dentist/ orthodontist as I suspect the reason has to do with your dental alignment. Fillers can help, but won't correct all the issues.

You have a small, recessed chin. I would see a plastic surgeon for a chin implant. Best of luck! 

There are many causes of excessive teeth show. One of the most common reasons is vertical maxillary excess. This means you have a longer midface which would require orthognathic surgery to correct (breaking your facial bones and shorting the face) and also causes chin wrinkling as you try to force your lips to close against each other. Other reasons may be a disporportionate jaw or soft tissues. The true cause can be determined by an evaluation of your facial anatomy and measurements. If you would prefer to avoid surgery. Non-surgical options can camouflage this area   such as lip filler to reduce the amount of teeth show and botox to relax the chin strain for an improved appearance. Hope this helps!Johnson C. Lee, MD
Board-Certified Plastic Surgeon
IG: @drjohnsonlee

 Hi, from the photos your chin is very weak and with history of requiring braces your occlusion (how the teeth come together) is likely the issue with not being able to close the lips together easily.Hope this helps.