A deep bite is one of the most common types of dental misalignment, technically known as a malocclusion, that affects both children and adults. It refers to an excessive vertical overlap between the upper and lower front teeth when the back teeth are brought together. This condition is more than an aesthetic issue, as the improper relationship between the teeth can lead to several functional and health complications over time. Correction is often necessary for long-term oral health.
Defining Vertical Overlap
A deep bite is characterized by a significant vertical overbite, which measures how much the upper front teeth cover the lower front teeth. In a healthy bite, the upper incisors should only cover the lower incisors by a small amount. This normal overlap is considered to be about 1 to 3 millimeters, or roughly 20 to 30 percent of the height of the lower front teeth crowns.
When this vertical overlap exceeds 40 percent, or about 4 millimeters, the condition is classified as a deep bite or excessive overbite. This measurement is taken perpendicular to the plane where the teeth meet. The increased overlap means the lower front teeth are nearly or completely hidden by the upper teeth when the jaw is closed. This extensive coverage creates a closed bite, which often causes the lower teeth to contact the gum tissue behind the upper teeth or the roof of the mouth.
Common Causes of Deep Bites
The development of a deep bite is often tied to a combination of factors, including the inherited shape and size of the jawbones. A skeletal deep bite occurs when there is a short anterior face height combined with a relatively large posterior face height, sometimes related to an upward and forward rotation of the lower jaw during growth. This rotation can cause the incisors to over-erupt because they lack the proper counter-force from the opposing teeth.
Other factors relate more directly to the teeth and surrounding soft tissues, known as dentoalveolar causes. A missing posterior tooth, for example, removes the vertical support that holds the bite open, leading to the front teeth continuing to erupt to find a point of contact. Certain habits, such as prolonged thumb-sucking or a persistent tongue thrust, can also affect alignment and eruption patterns. When the lower front teeth are tipped backward, or retroclined, they contribute to the excessive vertical overlap.
Impact on Oral Health and Function
An untreated deep bite can lead to significant functional damage and long-term oral health issues. One common consequence is excessive wear, or attrition, on the chewing surfaces of the front teeth. Since the lower incisors contact the back surfaces of the upper incisors with excessive force, the enamel wears down prematurely, compromising the tooth structure and increasing sensitivity.
The severe vertical overlap can result in trauma to the gum tissue. When the lower front teeth bite too high, they impinge directly into the palate—the gum tissue behind the upper front teeth—causing irritation, inflammation, and painful sores or ulcers. This traumatic contact can lead to periodontal problems and gum recession over time.
An improper bite relationship places undue stress on the temporomandibular joint (TMJ), which connects the jawbone to the skull. The deep bite forces the jaw to function in an unnatural position, straining the supporting muscles and contributing to a temporomandibular disorder (TMD). Symptoms associated with this joint strain include jaw pain, muscle disorders, headaches, and a ringing sensation in the ears. A deep bite can also affect the smile line and facial appearance, making the face look shorter or more rounded.
Treatment Options for Correction
Correction of a deep bite focuses on reducing the vertical overlap to a healthy range through controlled tooth movement. Orthodontic treatment is the common approach, involving appliances like traditional braces or clear aligners. These systems use archwires and specific mechanics to either push the front teeth deeper into the jawbone (intrusion) or to pull the back teeth out (extrusion), or a combination of both.
Orthodontists often employ specialized devices, such as bite ramps or bite planes, designed to prevent the back teeth from meeting initially. This allows the molars and premolars to erupt further and open the bite. For adults with a severe skeletal deep bite—where the jaw structure is the primary cause—orthognathic surgery, or corrective jaw surgery, may be considered. This surgical intervention repositions the jawbones to achieve a more balanced bite, working with orthodontic treatment. Following active treatment, retainers are necessary to maintain the corrected bite position and ensure long-term stability.