An overjet is a common alignment issue where the upper front teeth noticeably protrude past the lower front teeth, a condition sometimes referred to as “buck teeth.” This dental issue is a type of malocclusion, or “bad bite,” that can affect both the appearance of a person’s smile and their oral function. While many people have some degree of overlap between their upper and lower teeth, an excessive overjet represents a dental discrepancy that may require professional correction.
Defining Overjet and Overbite
Overjet describes the horizontal overlap between the upper and lower incisors. It is measured as the distance from the back surface of the upper front teeth to the front surface of the lower front teeth. For most people, the upper teeth naturally extend slightly in front of the lower teeth by about 2 millimeters, which is considered a normal and healthy overjet. An overjet is officially diagnosed when this horizontal protrusion exceeds 2 to 3 millimeters.
The condition is frequently confused with an overbite, but they represent two different types of misalignment. Overjet is a measurement of the horizontal distance, or how far forward the upper teeth stick out. In contrast, an overbite is the vertical overlap, indicating how much the upper teeth cover the lower teeth when the mouth is closed. While a small vertical overlap is also normal, an excessive overbite means the upper teeth cover the lower teeth too much.
Factors That Contribute to Overjet Development
The development of an overjet can stem from a combination of genetic and environmental factors. Skeletal issues are a significant contributor, often involving a disproportionate jaw structure. This may manifest as a lower jaw that is underdeveloped or positioned too far back compared to the upper jaw, causing the upper teeth to appear protruded. Since jaw size and position are often hereditary, a parent or sibling with an overjet increases the likelihood of developing the condition.
Beyond inherited factors, certain prolonged childhood habits can physically push the teeth into an excessive overjet. Extended thumb or finger sucking, particularly past the age of four, applies constant pressure that forces the upper front teeth forward. A habit known as tongue thrusting, where the tongue presses against the back of the upper teeth during swallowing, and the long-term use of pacifiers or bottles past the toddler years can also influence the development of this misalignment.
Functional and Health Implications
Correcting an overjet extends beyond aesthetic improvement, as the condition can lead to several tangible health and functional problems. One of the most significant concerns is the increased risk of dental trauma, with research suggesting that an untreated overjet can raise the risk of chipping or breaking the prominent upper teeth by up to 40%. These exposed teeth are more vulnerable to injury during falls, sports, or other accidents.
The misalignment can also impair normal oral functions, making it difficult to bite or chew food effectively. Some individuals with a pronounced overjet may also experience speech impediments, such as a lisp. Furthermore, the poor alignment can put excessive stress on the jaw joints, potentially leading to chronic facial or jaw pain and contributing to temporomandibular joint (TMJ) disorders.
Methods for Correction
Treatment for an overjet is highly dependent on the patient’s age and the underlying cause of the misalignment.
Early Intervention
For children and adolescents whose jaws are still developing, early intervention often involves functional appliances. These removable or fixed devices are designed to modify jaw growth, encouraging the lower jaw to grow forward and helping to reduce the horizontal gap. Early treatment also focuses on stopping harmful habits like thumb sucking and tongue thrusting through behavioral therapy or specialized appliances.
Orthodontic Treatment
For most patients, the primary method of correction involves traditional orthodontic tools like braces or clear aligners. Braces use brackets and wires to apply gentle, continuous pressure, gradually moving the protruding upper teeth back into a proper position. Clear aligners can also be effective for correcting mild to moderate overjet cases by utilizing a series of custom-made, removable trays. These methods often require the use of elastic bands to apply specific forces that help align the bite.
Surgical Correction
In severe cases, particularly in adults where the overjet is caused by a significant skeletal discrepancy between the jaws, a combined approach is necessary. This comprehensive treatment involves orthodontics to align the teeth, followed by orthognathic surgery, commonly known as jaw surgery. The surgeon repositions the jawbones to correct the underlying skeletal imbalance, providing the most ideal long-term result for complex cases.