What is a Scissors Bite?

If you’ve followed this blog for a while, you’ve become familiar with several types of malocclusion that can be treated through orthodontics. I’ve explained what overbite, underbite, and crossbite are, as well as approaches for treating these conditions.

Today I’m sharing information on scissors bite, a rare form of malocclusion.

Scissors bite is the term used to describe the condition when the upper molars are positioned outward, or the lower molars are positioned inward so that the molars miss each other and overlap when the mouth is closed.

It also can be accompanied by varying degrees of facial asymmetry, according to the American Journal of Orthodontics & Dentofacial Orthopedics.

This type of malocclusion may be caused by a lower dental arch that is too narrow.

It is important to treat scissors bite, because it interferes with the ability to properly chew food, since the molars don’t line up and therefore have no contact with each other. Untreated scissors bite also can cause gum recession, because the overlapping molars may rub against the gum line and apply too much pressure. Gum recession ultimately can lead to a host of other problems, including periodontal disease.

The good news is that scissors bite can be corrected in patients, regardless of whether they are children or adults. But the treatment approaches can be vastly different according to the severity of the case, and whether the patient is a growing child or an adult.

Interceptive treatment is recommended because scissors bite seldom corrects itself. Also, if a scissors bite exists while a child still has his/her baby teeth, it likely will remain present once the permanent teeth erupt. Postponing treatment could mean that more extensive, complex treatment will be required to correct the problem as the child grows older.

Common treatment approaches

Typically, patients who have a scissors bite malocclusion in which only a few teeth are out of proper alignment can be successfully treated with orthodontics, provided they have a normal overbite.

Each orthodontic case is unique, and scissors bite cases vary from patient to patient. This means there never is a one-size-fits-all approach to getting teeth into proper alignment, but following are some popular appliances used in various treatment approaches.

Intermaxillary cross-elastics- These elastics are applied to the upper teeth and connected to the lower teeth in a cross pattern. That means the elastic may connect from the tongue side of your upper arch to the cheek side of your lower arch.

Trans-palatal arch appliance- This appliance is used to maintain the upper jaw’s arch width and move molars into positions that can’t be accomplished with wires alone. We band the appliance around the first molars on each side of the mouth, and a thin wire spans the roof of the mouth.

Lingual arch appliance- This appliance acts as a space maintainer to keep molars from drifting forward, and prevents them from blocking the space where permanent teeth will eventually erupt.

Temporary anchorage devices– Use of these devices can decrease arch width and upright the molars to correct scissors bite without surgery.

The surgical approach

In orthodontic cases where multiple teeth are involved in the scissors bite and the overbite is deep, orthognathic surgery may be necessary.

In these cases, I work in collaboration with an oral surgeon to map out a treatment plan that will provide the most successful result.

Surgical correction of scissors bite could include a procedure known as dentofacial osteotomy, where jaw bone is cut, moved, modified and realigned to correct the relationship between the molars in the upper and lower jaws.

Final thoughts

The American Association of Orthodontists recommends that children be evaluated by an orthodontist at age 7. This is a good time to determine whether scissors bite exists, and to monitor a child’s growth to identify the best time to address the issue.

If you are an adult who has scissors bite, or you suspect your child has this type of malocclusion, call our office to schedule an appointment. We will conduct a complete exam, present a diagnosis and recommend a treatment plan.