A palatal expander is an orthodontic appliance used to address a narrow upper jaw, known as maxillary constriction. This device applies gentle, outward pressure to the roof of the mouth, gradually widening the upper arch of the teeth and the underlying bone structure. The primary goal of this treatment is to create necessary space and correct alignment issues that affect the bite. This expansion is most effective in growing patients, typically children and adolescents, whose bones are still developing and responsive to orthopedic force. The appliance remains fixed, working continuously to reshape the maxilla.
The Purpose of Palatal Expansion
A narrow upper jaw can lead to several functional and structural problems. The most common indication for expansion is a posterior crossbite, where the upper back teeth bite inside the lower back teeth, which can cause uneven tooth wear or asymmetric jaw growth. When the upper arch is too narrow, there is insufficient space for permanent teeth to erupt correctly, leading to severe dental crowding. Widening the palate creates the room needed for teeth to align naturally, sometimes eliminating the need for future tooth extractions.
The treatment also improves the patient’s breathing capacity. Since the floor of the nasal cavity is the roof of the mouth, expanding the palate increases the width of the nasal passages. This increase in nasal airway volume can help alleviate issues such as chronic mouth breathing or snoring associated with restricted upper airways.
The Science Behind Jaw Widening
The mechanism behind true palatal expansion relies on separating the midpalatal suture, a fibrous joint that runs down the center of the roof of the mouth. In young patients, this suture has not yet fully fused, allowing the two halves of the upper jawbone (maxilla) to be physically separated. The Rapid Palatal Expander (RPE) applies a lateral, orthopedic force to this suture, causing a controlled skeletal widening of the jawbone itself, not merely tooth movement.
As the suture separates, the body’s natural healing process, known as osteogenesis, is triggered. New bone tissue gradually forms within the gap created by the separation, stabilizing the new, wider structure of the maxilla. This procedure is most successful before the late teenage years, as the suture becomes increasingly rigid and resistant to non-surgical separation as a person matures. The goal is to achieve a significant skeletal effect, which is more stable and less prone to relapse than simply tipping the teeth outward, a phenomenon called dental expansion.
Installation and Activation Timeline
The palatal expander is a custom-made appliance, typically fixed to the upper back molars using metal bands or a bonding material. Once the device is cemented into place, the active phase of treatment begins, involving daily or twice-daily activation by the patient or a guardian. A small, specialized key is inserted into a central screw mechanism and turned to advance the screw, incrementally widening the device. Each turn applies a precise amount of pressure, usually resulting in a movement of about 0.2 to 0.5 millimeters per day.
This active expansion phase typically lasts between two to four weeks, depending on the amount of widening required. A common sign that the expansion is successfully separating the suture is the appearance of a temporary gap between the two upper front teeth. Once the desired width is achieved, activation stops, but the expander remains in the mouth for a stabilization or retention phase. This phase usually lasts for about six to nine months, allowing the new bone to mineralize and permanently secure the maxilla in its corrected position.
Caring for the Expander and Post-Treatment Steps
Maintaining hygiene around a fixed expander requires careful attention. Patients must use specialized tools to clean thoroughly beneath the appliance and around the bands.
- Soft-bristled toothbrush
- Interdental brush
- Water flosser
- Rinsing the mouth vigorously after every meal to dislodge trapped food particles
This meticulous cleaning prevents plaque buildup, which could otherwise lead to gum inflammation and tooth decay.
Patients should expect a temporary adjustment period after the expander is placed. Common side effects, which subside within a few days, include increased salivation, a temporary lisp, and mild discomfort or pressure near the bridge of the nose or cheekbones. During treatment, it is important to avoid hard, sticky, or crunchy foods like nuts, caramels, or popcorn, as these can easily damage the appliance or loosen the bands. After the expander is removed, a retainer or a fixed holding arch is often placed to maintain the new width and prevent the jaw from shifting back, ensuring long-term success.