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

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