Types of Underbites: Causes, Risk Factors & Treatment Options

What is an Underbite?

An underbite is a class III orthodontic malocclusion where the lower jaw is pushed forward. In a normal bite, the front teeth should slightly overlap the lower teeth.

An underbite is when the lower front teeth and jaw are positioned in front of the upper front teeth and jaw. An underbite can be mild or severe and requires orthodontic treatment to fix.

What Causes an Underbite?

The primary causes of an underbite include:

• Genetics (primary cause)
• Jaw malformation
• Teeth misalignment
• Tongue thrusting
• Thumb sucking as a child
• Sucking on a pacifier as a baby (more frequently and longer than normal)
• Drinking from a bottle long-term (babies)
• Facial and jaw injuries
• Jawbone tumors
• Mouth breathing

Types of Underbites 

There are two types of underbites:

1. Dental underbite — Forms due to teeth misalignment. This is particularly the case when a crossbite appears in the front of the mouth rather than the side.
2. Skeletal underbite — Caused by a deformity of the jawbone. This type of malocclusion is usually genetic (present at birth). 

Underbite Correction: Common Treatment Options

Underbites are commonly found in children and adolescents.

Although, the misalignment usually resolves once permanent teeth emerge. If you are concerned your child may have a true underbite, consult your local orthodontist to discuss your options. 

Treatment for an underbite depends on the patient’s age and the severity of misalignment.

Underbite Treatment for Children

Some underbites form due to birth defects, such as a cleft lip and palate. The earlier you seek treatment for your child’s underbite, the less likely surgery will be necessary later in life.

If a severe underbite isn’t noticeable or present at birth, orthodontists recommend waiting to start treatment until your child starts developing permanent teeth. Permanent teeth typically start growing in around age 7.

According to Dr. Nandita Lilly, one of NewMouth’s in-house dentists, “the correction methods used to treat an underbite are based on factors such as the extent of the underbite and the child’s age. So it is imperative to see your dental professional as early as possible so the child’s bones and palate can be more easily manipulated.”

Common underbite treatment for children include:

• Dental braces
• Palatal expansion
• Reverse pull headgear
• Surgery

Underbite Treatment for Adults

If an underbite is not corrected in early childhood, it is more likely that other dental conditions and jaw issues have developed into adulthood.

Treatment is still possible for adults, but choices are limited since the jaw and teeth have fully developed. Depending on the patient, surgery is usually necessary at this stage of life.

Common treatment options for adults include:

• Dental braces
• Invisalign (clear aligners)
• Jaw surgery

Complications of Untreated Underbites

Underbites and overbites should never go uncorrected. If left untreated, severe pain, jaw problems, and dental conditions can result over time. 

Underbites can also cause sleeping problems, headaches, and discomfort without proper treatment. 

Common complications of an untreated underbite include:

• Increased risk of tooth decay
• Increased snoring, sleep apnea, and mouth breathing
• Temporomandibular joint disorders (TMD)
• Difficulties speaking (lisps and slurred speech), chewing food, and swallowing
• Increased risk of gum disease
• Structural mouth and smile changes
• Irregular or crooked teeth
• Bad breath, even after brushing or rinsing with mouthwash
• Poor mental health and low self-esteem
• Increased need for invasive jaw surgery
• Headaches
• Earaches
• Cracked or worn-down teeth