An overbite is the vertical overlap of the upper front teeth over the lower front teeth, a common trait in human dental anatomy. The term describes a component of dental occlusion, which is how the upper and lower teeth meet. While a slight degree of overlap is standard and necessary for proper function, an excessive overlap becomes a clinical issue known as a deep bite or malocclusion. Understanding the difference between a normal, functional overlap and a problematic deep bite is the first step toward maintaining optimal oral health.
Defining the Overbite Spectrum
The overbite measures the vertical distance the upper incisors cover the lower incisors when the back teeth are closed. A functional and healthy bite requires a small vertical overlap to protect the soft tissues of the mouth and ensure efficient chewing. This normal range is defined as the upper teeth covering approximately one-quarter to one-third of the lower teeth, equating to about 1 to 3 millimeters (mm) of vertical overlap.
When the overlap exceeds this range, it is classified as an excessive overbite or a deep bite, which is considered a malocclusion. A deep bite often means the upper teeth cover the lower teeth by 4 mm or more, or by over 50% of the lower incisor height. It is important to distinguish the overbite (vertical overlap) from the overjet, which refers to the horizontal protrusion, or how far the upper front teeth stick out in front of the lower teeth. Both measurements are used by orthodontists to determine the alignment and stability of the bite.
Primary Factors Contributing to Overbite
The development of an overbite stems from inherited and environmental influences that affect jaw growth and tooth positioning. One major category is skeletal, relating to the size and shape of the jawbones. A common skeletal factor involves a discrepancy where the lower jaw is positioned slightly behind the upper jaw, or is simply smaller. This structural difference is often inherited and influences the vertical relationship between the dental arches.
Environmental or habitual factors, particularly those present during childhood development, also play a significant role. Prolonged habits such as thumb sucking or pacifier use past the toddler years can push the front teeth out of alignment. Additionally, a persistent tongue thrust, where the tongue pushes against the back of the front teeth during swallowing, can contribute to incorrect positioning. These acquired habits can worsen an existing slight overbite or contribute to the formation of a deep bite.
Functional and Health Issues of Severe Overbites
A deep bite, which extends beyond the normal range, can lead to several functional and health complications. One common issue is excessive wear on the teeth, particularly the lower front teeth. The constant friction between the upper and lower teeth can cause the enamel to erode prematurely, leading to sensitivity and an increased risk of chipping or fracture.
Severe overlap can also cause soft tissue damage, where the lower incisors bite directly into the gum tissue behind the upper front teeth (the palate). This trauma can result in painful sores, gum recession, and other periodontal problems. Furthermore, the misalignment can strain the temporomandibular joints (TMJ), potentially causing jaw pain, chronic headaches, and difficulty chewing.
Orthodontic Correction Methods
When an overbite is determined to be a deep bite requiring correction, a range of orthodontic treatment options are available. The goal of treatment is to reduce the vertical overlap, often by intruding (pushing up) the upper front teeth or extruding (pulling down) the back teeth to open the bite. Traditional fixed braces are a reliable method, using brackets and wires to apply continuous, precise pressure to reposition the teeth.
Clear aligner systems, such as Invisalign, can also be effective for mild to moderate deep bites by guiding the teeth into better vertical alignment. Orthodontists may also use specialized appliances, like bite turbos or bite pads. These small ramps are placed on the back of the front teeth to temporarily prevent the lower teeth from fully engaging the upper teeth, allowing the back teeth to move into a more stable position. For the most severe cases, particularly those involving significant skeletal discrepancies in adults, orthognathic surgery (jaw surgery) may be necessary to reposition the jawbones for a stable, functional bite.