A crossbite is when a tooth or teeth are abnormally closer to the buccal (cheek) region or lingual (tongue) region of the mouth than the teeth above or below them. Essentially, a crossbite occurs when any of the upper teeth fit into the wrong side of the lower teeth.
Crossbites fall into the following categories:
- Dental- crossbites that only involve teeth that are tipped lingually or buccally.
- Skeletal- caused by discrepancies in jaw size and position. Discrepancies can involve the maxilla, (upper jaw), mandible (lower jaw) or both.
- Functional- the result of an occlusal interference that causes the mandible to shift to achieve maximum occlusion. A deviation in upper and lower midline alignment is a good indication of a functional crossbite.
- Anterior–occurring in the front of the mouth. An underbite is characterized by an anterior crossbite where the lower front teeth extend farther than the upper front teeth.
- Posterior- in the back of the mouth.
- Unilateral – occurring on one side of the mouth.
- Bilateral- occurring on both sides of the mouth.
What Causes a Crossbite?
Crossbites can be inherited, functional, or caused by environmental factors. Environmental factors that cause crossbites include mouth breathing and prolonged thumb sucking or pacifier use. Because children’s jaws are still growing, they are most susceptible to environmental influences.
Crossbites are said to be functional when they are the result of an occlusal interference that causes the mandible to shift to achieve maximum occlusion.
Complications Involving Crossbites
- Facial asymmetry- If you look in the mirror and move your lower jaw to the left, right or forward until your lower teeth protrude past your upper teeth, this should give you an idea of what facial asymmetry caused by a crossbite looks like.
- Temporomandibular joint disorders – A misaligned bite can place increased pressure on one or more of your temporomandibular joints, which can lead to TMJ disorders. These disorders are characterized by pain associated with the joints and chewing muscles.
- Speech impediments- Crossbite sufferers can have difficulty pronouncing certain words and sounds.
- Enamel wear- Enamel can become worn where teeth overlap improperly.
- Receding gums- Extreme crossbites can cause teeth to press against the gum lines of the opposite jaw. This constant pressure causes the gums to recede permanently.
- Teeth grinding
After a crossbite has been diagnosed, we must determine the cause and take into account your child’s age and various environmental factors to create an appropriate treatment plan. Braces can be used to treat dental crossbites at most ages, but craniofacial appliances or surgery are required to treat problems that stem from skeletal discrepancies.
Craniofacial appliances are ideal, as they can prevent the need for invasive surgery, but are most effective when used to treat children who are 8 or younger. The American Association of Orthodontists suggests parents have their children seen by an orthodontist by age 7, or at the first sign of a problem.
Appliances Used to Treat Crossbites
Maxillary expander– These appliances are used to provide a better teeth/skeletal relationship by increasing the circumference of the maxillary arch. Maxillary expansion can improve not only bite alignment, but also chewing abilities and jaw joint symmetry.
Haas and Hyrax– These appliances are considered rapid palatal expanders, which as the name implies, are designed for fast, efficient expansion.
RPEs are placed in the roof of the mouth – also referred to as the upper palate – and secured to teeth by various means. Each appliance has a screw that when turned with a special key, gradually widens the upper arch. The widening is achieved by separating the midpalatal suture, which is the suture that runs along the middle of the upper palate. A suture is a type of interlocking, immovable joint common to the bones of the skull. We are able to widen the jaw with pressure from an RPE because the midpalatal suture does not fuse until around age 12. Once the desired width has been achieved, the appliance is left in for an average of three months to allow new bone to fill in the opened space.
Quad Helix, Porter and W arch– These appliances are all constructed with a W-shaped arch wire that spans the upper palate and attaches to the lingual- or tongue side – of molar bands. There are no screws involved with these appliances.
The Quad Helix and W arch are fixed appliances, and the Porter arch is classified as fixed-removable, which means it can be worn as a removable device, or secured as a fixed device. Although used infrequently, the Porter arch can provide more precise adjustments when used as a removable appliance.
Mandibular expanders– Unlike the maxilla, the mandible does not contain a suture that can be opened and used to widen the jaw on a skeletal level. Therefore, mandibular expanders are used to achieve dental expansion.
Lip bumpers– These appliances are used in upper and lower jaws, but are used most often in the lower jaw. They are constructed of heavy gauge wire that is inserted into tubes bonded or welded to the buccal side of the first primary molars. Lip bumpers can be fixed-removable, or fixed.
The process by which a lip bumper moves teeth is unique. It initially causes the molars to which it is attached to tip toward the cheeks, then a change in muscle balance moves the rest of the teeth. As the molars tip bucally, the force of the buccinator muscles is reduced, which increases tongue pressure, thus producing movement.
Studies have proven that posterior crossbite correction achieved with maxillary expansion has a high rate of stability, so you can be confident that your child’s smile will stay healthy and straight for years to come.
Tonsillectomy– Enlarged tonsils and adenoids can cause mouth breathing in children, which contributes to poor oral development. We may refer your child to a general physician if we determine crossbite treatment would benefit from tonsil removal.
Braces– Braces provide effective treatment of crossbites that do not include skeletal discrepancies, and are sometimes prescribed following craniofacial treatment to enhance results. We offer several types of metal and invisible braces in our Miami – based practice.
Correcting a malocclusion early, especially one that falls into the functional category, can help prevent problems and may even change your child’s facial structure for the better. Call today to schedule your child’s first orthodontic evaluation.