A palatal expander is an orthodontic appliance designed to widen a narrow upper jaw, known as the maxilla. This device works by applying gentle, continuous pressure against the two halves of the upper jawbone, which are joined by a flexible seam called the mid-palatal suture. The primary goal of this intervention is to correct issues such as a crossbite or to create necessary space for crowded permanent teeth. While the total time the expander remains in the mouth varies, it is typically used in growing children and teens whose skeletal structures are still malleable.
The Active Expansion Period
The first phase of treatment involves the active widening of the maxilla, accomplished by incrementally turning a screw mechanism built into the expander. An orthodontist instructs the patient or a parent to turn a specific key, usually once or twice daily, applying a controlled force that slowly separates the two halves of the upper jawbone. This active phase lasts until the desired width is achieved, typically spanning between two to six weeks. A visible sign that the expansion is working is the formation of a temporary gap (diastema) between the two upper front teeth. Once the orthodontist confirms the correction is complete, the turning process stops.
The Stabilization and Retention Phase
After the active turning stops, the expander immediately enters the stabilization phase, acting as a passive retainer. The expander must remain in place to prevent the newly widened arch from collapsing, a phenomenon known as relapse. During this phase, the device holds the expanded position, allowing the body’s natural processes of bone remodeling to take place, where specialized cells deposit new bone across the separated suture. To ensure the new bone fully matures and stabilizes the maxilla, the expander is typically left in place for an additional four to six months after the last turn. This passive retention period may extend up to nine months, depending on the patient’s biological response, as premature removal risks the upper jaw shifting back toward its original, narrow state.
Variables That Determine Total Duration
The total time an expander stays in, including both the active and retention phases, generally ranges from six months to a year. Patient age is the most influential variable; the mid-palatal suture is more flexible in younger children, allowing for quicker treatment than in older adolescents whose bone structure is denser. The severity of the original jaw discrepancy also plays a substantial role. A more complex issue, such as a severe crossbite, necessitates a longer active phase and a longer retention period to ensure stability. Finally, the type of appliance used affects the total time, as fixed expanders ensure continuous compliance, leading to a more predictable and often shorter overall treatment length compared to removable options.