A crossbite is a dental misalignment where one or more upper teeth fit inside the lower teeth when biting down. This contrasts with a normal bite, where the upper teeth slightly overlap the lower teeth. Crossbites are categorized as anterior (involving the front teeth) or posterior (affecting the back teeth). If left uncorrected, a crossbite can cause uneven tooth wear, gum recession, and jaw joint problems. Treatment is highly individualized, depending on the patient’s age and whether the issue is primarily skeletal (jaw size) or dental (tooth position).
Early Treatment Using Expansion Devices
The most effective time for treating skeletal posterior crossbites is during childhood, when the jawbones are still growing and pliable. This method targets the upper jaw (maxilla), which consists of two halves joined by an unfused suture in the center of the palate. The goal is to widen the upper arch to match the lower arch, correcting the skeletal discrepancy.
Orthodontists typically use a fixed appliance called a Rapid Palatal Expander (RPE). The RPE is cemented to the back upper molars and uses a screw mechanism activated by a small key. Turning the key applies a gentle, continuous force, gradually pushing the two halves of the maxilla apart. The active expansion phase usually lasts three to six weeks, achieving a widening rate of about 0.5 millimeters per day.
After achieving the desired width, the expander remains in place for a retention period of five to six months. This retention allows new bone to form and solidify in the gap along the midpalatal suture, preventing the jaw from collapsing back. The RPE is highly successful in young patients because it addresses the underlying skeletal issue before the growth plates fully fuse around puberty.
Orthodontic Methods for Tooth Repositioning
After skeletal correction, or when the crossbite is purely dental, the next phase involves precisely moving individual teeth.
Traditional Braces
Traditional braces use brackets bonded to the teeth, connected by archwires that apply consistent pressure to guide alignment. For crossbite correction, these fixed appliances are often paired with orthodontic elastics (rubber bands). These elastics run from the upper arch to the lower arch to pull misaligned teeth into their proper position.
Clear Aligners
Clear aligner systems, such as Invisalign, offer a discreet alternative for correcting mild to moderate dental crossbites. These custom-made, removable plastic trays apply controlled forces to shift teeth over time. A new set of aligners is worn every one to two weeks. Aligners can push upper teeth forward or outward, correcting both anterior and posterior dental crossbites. Both braces and aligners are effective for repositioning teeth to achieve a final, stable bite.
Advanced Solutions for Adult and Severe Cases
In adult patients, the midpalatal suture is fully fused, meaning a standard RPE cannot achieve skeletal expansion alone. Severe crossbites caused by a significant jaw size mismatch require a more complex approach.
Surgical Options
Orthognathic surgery, or corrective jaw surgery, physically repositions the upper jaw, lower jaw, or both into a functional, aligned relationship. This procedure typically takes two to three years, combining surgery with orthodontics to move the teeth before and after the operation. An alternative for adults needing upper jaw widening is Surgically Assisted Rapid Palatal Expansion (SARPE). SARPE involves a surgeon weakening the jawbone structure to allow the RPE to effectively separate the fused suture.
Camouflage Treatment
For patients with moderate skeletal issues, an orthodontist may recommend camouflage treatment. This involves moving the teeth to mask the underlying jaw discrepancy, potentially avoiding surgery entirely.
Maintaining Correction After Treatment
The final phase of crossbite correction is retention, which is necessary because teeth have a natural tendency to drift back toward their original positions, a phenomenon known as relapse. Retainers are custom-made devices designed to hold the teeth firmly in their new positions while the surrounding bone and ligaments stabilize. Orthodontists prescribe two main types of retainers:
- Fixed retainers: These consist of a thin, braided wire that is permanently bonded to the tongue-side surface of the front teeth, offering continuous stability.
- Removable retainers: These include the classic Hawley retainer (metal wires and acrylic) or clear plastic trays, known as Essix retainers, which fit snugly over the entire arch.
Long-term, consistent use of a retainer, often nightly for years or indefinitely, is the most important factor in ensuring the crossbite correction remains stable and permanent.