The upper and lower front teeth tend to erupt in the mouth around the age of 7. How they decide to come in can determine whether your child will develop an underbite. I have seen many 7-9 year olds come into my office and the parents would tell me, “my child did not have this underbite before and now they do”. Although rare, it is possible that your child has a normal bite when their baby teeth are in, but as the permanent incisor start coming in an underbite can develop.
Underbites can be caused by a strong lower jaw, a setback upper jaw, lower teeth that protrude, upper teeth that are set back or any combination of the above. The best way to know what is the cause of the underbite is to visit an orthodontist. The orthodontist can take a special x-ray, called a cephalogram, and it will show the cause of the underbite. This x-ray allows the orthodontist to see how the jaws fit together and how the teeth fit together within the jaws. Finding out what caused the underbite will determine the solution.
Frequently, the underbite can be treated with orthopedics or braces. Early treatment is important as the orthodontist can take advantage of the patient’s growth and help manipulate the patient’s jaws into a more favorable relationship to eliminate the underbite. Correcting an underbite early, can prevent gum recession caused by the upper teeth biting behind the lower teeth and pushing the lower teeth forward through the jaw bone.
Even after early treatment, the patient’s underbite can return if there is a strong genetic disposition to grow that way. You may ask then why should you even bother with early treatment if the underbite will return? The severity of the underbite returning can be reduced so that when the patient is done growing and all the permanent adult teeth are in, treatment may simply involve braces or clear aligner therapy.
About 0.5% of the population is not so straightforward in their underbite correction and may require more complex treatment such as jaw surgery by an oral surgeon to establish more normal skeletal relationship between the upper and lower jaw. This population can be identified early on and if the underbite is severe, the best course of action is to wait until growth is completed so that surgery can correct the relationship of the jaws when they are adults. The jaw surgery will improve the patient’s physical appearance, speech and function during chewing. It is life changing and improves the quality of life!