Clear aligners are a popular orthodontic choice, offering an aesthetically pleasing way to straighten teeth without visible metal brackets and wires. A common reason people seek this treatment is to close gaps between teeth, a condition known medically as diastema. These custom-fitted trays effectively address spacing issues, from a single gap to multiple spaces throughout the dental arch. This article details the mechanics of how aligners close these spaces, the factors determining treatment success, and what a patient should expect.
How Aligners Close Gaps Between Teeth
Clear aligners operate by applying gentle, continuous force to gradually move teeth into their desired positions. The treatment begins with a precise digital map of the patient’s current tooth positions and the final, desired alignment, which is broken down into a series of incremental movements. Each aligner tray in the sequence is slightly different from the last, designed to move the teeth a fraction of a millimeter closer together.
The aligners themselves are made from thin, medical-grade plastic that fits snugly over the teeth, acting as a casing that dictates the direction of movement. To ensure necessary grip and directional force, small, tooth-colored composite shapes, called attachments, are often bonded temporarily to certain teeth. These attachments create an active surface that the aligner plastic can push against, which is especially important for closing a gap, requiring horizontal force to slide teeth along the arch.
For space closure, the attachments are strategically placed to help achieve bodily movement, preventing the teeth from simply tilting into the gap. The specific design and positioning of these attachments, often having a flat or beveled surface, ensure the aligner applies force perpendicular to that surface, maximizing the efficiency of the push. The entire process is pre-programmed digitally, allowing the orthodontist to control the movement of the crown and the root simultaneously for a stable result. This sequential application of controlled pressure systematically reduces the space until the gap is fully closed and the teeth are properly aligned.
Factors Determining Gap Treatability
The suitability of clear aligners for closing a gap depends heavily on the size of the space and its underlying cause. Aligners are highly effective for closing small to moderate gaps, typically ranging from 1 to 4 millimeters. Larger spaces or generalized spacing across the entire arch may still be treatable, but often require a longer treatment duration or the use of auxiliary orthodontic tools.
The origin of the diastema is a primary consideration because some causes require pre-treatment or concurrent auxiliary procedures. For example, a common cause of a gap between the two upper front teeth is an oversized or low-hanging labial frenum, the piece of tissue connecting the lip to the gums. In such cases, a simple surgical procedure called a frenectomy may be necessary to remove the excess tissue before or during the aligner treatment to prevent the gap from reopening.
Other factors that can complicate gap closure include missing teeth, which create large spaces, or habits like tongue thrusting, where the tongue pushes against the front teeth. Periodontal issues, such as gum disease that results in bone loss, can also cause teeth to drift apart, and these underlying conditions must be addressed before or alongside tooth movement.
In some instances, the orthodontist may recommend interproximal reduction (IPR), which involves polishing small amounts of enamel from the sides of teeth to create space elsewhere. They may also use temporary anchorage devices for more complex movements. If the issue involves skeletal misalignment or very complex movements, traditional braces might be a more predictable choice, though aligners can often be used for the majority of the treatment.
What to Expect During and After Treatment
Once the treatment plan is finalized, patients must commit to wearing the aligners for 20 to 22 hours per day, removing them only for eating, drinking anything other than water, and oral hygiene. Compliance with this wear time is the most important factor for achieving the predicted gap closure on schedule. The aligners are typically changed every one to two weeks, with each new tray causing mild pressure for the first few days, which signals that the teeth are moving.
The total treatment time for gap closure varies; mild spacing may be resolved in 6 to 8 months, while more extensive or complex cases may take 12 to 18 months or longer. The movement to close a simple gap is often faster than other types of orthodontic movement, allowing patients to see noticeable progress within weeks. Throughout the process, the patient will have check-up appointments every six to eight weeks to ensure the teeth are tracking the planned movement correctly.
The final phase is retention, as teeth have a strong tendency to shift back to their original, gapped positions, known as relapse. To maintain the closed gap, retainers must be worn as prescribed, transitioning from full-time wear immediately after treatment to nightly wear indefinitely. Retention may involve a removable retainer, like a custom-fitted clear tray, and often a fixed retainer, which is a thin wire bonded to the back surfaces of the front teeth.