WHY DO I HAVE GAPS BETWEEN MY TEETH? Search Results Featured snippet from the web Gaps may form when a person's teeth are too small for the jaw bone. As a result, teeth are spaced too far apart. ... Certain bad habits may also trigger a gap between the teeth. Children who suck their thumb may form a gap because the sucking motion puts pressure on the front teeth, causing them to pull forward. Why are my teeth spreading apart? Teeth can spread apart when a muscle in the front of the mouth relaxes as we age. Periodontal disease, caused by bacteria living under gum tissue, can also lead to spreading