An overbite is one of the most common bite misalignments, or malocclusions, where the upper front teeth extend vertically over the lower front teeth. While a minor overlap is considered anatomically normal, a severe overbite can disrupt the balance of the oral and facial structure. This excessive overlap introduces forces and strain that affect both the teeth and the delicate mechanics of the jaw joint.
Defining Overbite and Jaw Mechanics
The term “overbite” refers to the vertical overlap between the upper and lower front teeth when the mouth is closed. A small overlap, typically one to two millimeters, is considered healthy alignment. When this vertical overlap exceeds three millimeters, it is classified as a deep bite or a Class II Malocclusion, where potential problems begin to arise. This condition is distinct from an “overjet,” which describes a horizontal protrusion where the upper teeth stick out too far forward over the lower teeth. The jaw is connected to the skull by the Temporomandibular Joint (TMJ), a complex structure that includes a cushioning articular disc necessary for smooth movements like chewing and speaking.
Direct Impact on Temporomandibular Joint Function
A severe overbite directly affects the jaw by forcing the lower jawbone (mandible) to settle into an incorrect position. The excessive vertical overlap often pushes the lower jaw backward, which compresses the temporomandibular joint (TMJ). This mechanical imbalance places chronic, uneven pressure on the muscles and ligaments controlling jaw movement. This sustained strain often leads to Temporomandibular Disorder (TMD).
The misalignment can cause the articular disc within the TMJ to become displaced or slip forward. When the jaw moves, the bone against the misplaced disc can produce clicking, popping, or grating sounds, medically termed crepitus. Chronic muscle tension from the misaligned bite often manifests as frequent headaches around the temples and forehead. People with TMD also experience pain or tenderness in the jaw joint, or a dull ache radiating through the face, which can limit the ability to fully open the mouth.
Related Consequences Beyond the Jaw Joint
The consequences of a deep overbite extend past the joint mechanics to affect the teeth and surrounding soft tissues. When the upper teeth significantly overlap the lower teeth, improper contact leads to excessive wear, or attrition, on the enamel of the lower front teeth. In severe cases, the lower incisors may repeatedly strike the gum tissue behind the upper front teeth. This traumatic contact can cause gum recession, inflammation, or soft tissue injury on the palate, increasing the risk of periodontal issues. Functionally, the misalignment complicates biting and chewing, making it difficult for the front teeth to shear through food and placing undue stress on the back molars.
Diagnosis and Treatment Pathways
Addressing an overbite begins with a comprehensive evaluation by a dental professional, typically an orthodontist. Diagnosis involves a thorough visual inspection of the teeth and bite relationship, often supplemented by diagnostic tools. These tools include dental impressions or digital scans to create a three-dimensional model of the teeth and jaw. To determine the underlying cause, whether dental or skeletal, X-rays are routinely used, such as panoramic films or a cephalometric analysis. The cephalometric X-ray provides a side-view of the skull to measure the precise relationship between the upper and lower jawbones.
Treatment is tailored to the patient’s age and the severity of the misalignment. Non-surgical treatments utilize orthodontic appliances like traditional braces or clear aligners to reposition the teeth over time. In growing patients, functional appliances can guide jaw growth to correct skeletal discrepancies. For adults with a severe skeletal overbite, a combination of orthodontics and orthognathic surgery may be necessary to reposition the jawbones for a lasting correction.