underbites

An underbite, also known as prognathism or class III malocclusion, is a dental condition in which the lower teeth and jaw extend in front of the upper teeth when the jaws close. Underbites can be categorized as dental, where the teeth are misaligned, or skeletal, where the jawbones themselves are positioned forward relative to the upper jaw. In some cases, both dental and skeletal factors contribute to an underbite.

Causes and risk factors vary. Genetic factors play a significant role in skeletal class III malocclusion. Environmental influences during growth, habits such as prolonged mouth breathing, tongue thrusting, or early loss of primary teeth can affect bite development. Weaker upper jaw growth or overgrowth of the lower jaw can also lead to an underbite. In adults, underbites are typically the result of longstanding skeletal imbalance or late orthodontic relapse.

Diagnosis typically involves a clinical examination, bite analysis, and imaging. Dentists and orthodontists assess how the upper and lower teeth meet, look for signs of jaw misalignment, and may use X-rays, cephalometric radiographs, or 3D imaging to distinguish between dental and skeletal contributions. Dental casts or digital scans may be used to plan treatment.

Treatment depends on age, severity, and whether the issue is dental or skeletal. In children with growing jaws, orthodontic appliances, such as functional appliances or palatal expanders, can guide jaw growth. Some cases require headgear to influence the bite. In growing patients, early intervention can reduce the need for surgery later. In adults, orthognathic (jaw) surgery combined with orthodontics is often recommended for substantial skeletal discrepancies. Braces or clear aligners can correct tooth alignment, and retention is important after treatment. Untreated underbites may lead to uneven wear, chipped teeth, jaw pain, TMD, speech difficulties, and cosmetic concerns.