One of the most frustrating problems that occurs during orthodontic treatment (or reappears afterwards) is space between the teeth that just won’t close. This may be due the teeth themselves, the bone around the teeth, or interference from teeth in the other arch. Let’s look at each of these possible causes.
The sizes and shapes of your teeth may be the cause
The most common reason spaces don’t close (or stay closed) is the size, shape, or position of the teeth themselves. A tooth may be too narrow at the top, too narrow at the bottom, or just too small overall. Such a tooth just can’t fill the entire space between two normal sized, correctly positioned teeth. If a tooth is too small or is shaped funny, it must be resized or reshaped. Removing tooth structure or adding restorative material (composite or porcelain) may be performed by your orthodontist or your general dentist.
The angulation of the teeth can prevent space closure
Sometimes the angulation of the teeth can also prevent full space closure. If the roots of two adjacent teeth are touching beneath the bone, it may prevent the crowns from being brought together fully. If the teeth are tipped towards each other, bringing the tops of the crowns together may leave a “space” below the contact point that looks like a triangular space just above the gums. Evaluating the position of your teeth with an x-ray helps the orthodontist know whether he needs to move a tooth or reshape it to eliminate the space.
The gums, bones, and ligaments around the teeth may contribute
Sometimes the teeth are normal but there are issues with the surrounding structures. If there is a problem with the ligaments around the root of a tooth (known as ankylosis), it may be impossible to move that tooth to close a space. In this case veneers or crowns may be necessary to make the tooth wider. In some patients the tissue between two teeth may be too thick or dense to allow full space closure (like the frenum between the upper central incisors). The cure for this is to remove the extra tissue in a procedure known as a frenectomy or a gingivectomy.
Tongue posture or pathology may also prevent space closure
Patients with tongue posturing issues (commonly referred to as “tongue thrust”) may also develop spaces between the teeth that are difficult to close and keep closed. Some patients have success performing tongue exercises (myofunctional therapy), while others require “tongue spurs” during treatment and permanent retention afterwards. Lastly, in rare cases, a patient may have a cyst or growth in the bone between the roots of the teeth that create a space or prevent one from being closed. The remedy for this is the removal of the pathology by an oral surgeon.
Teeth in opposite arch (the bite) may keep spaces from closing
Finally, if there are stubborn spaces that either just won’t close or immediately reopen after they are closed, and none of the above mentioned reasons seem to be the cause, the problem may be the teeth in the other arch (the bite). The lower front teeth can push against the backs of the upper front teeth and create spaces. Similarly, a cuspid or bicuspid in one arch can wedge between two teeth in the other arch to create a space or prevent one from closing. Spaces created by the opposing occlusion can be closed only if the teeth involved are moved or reshaped.