“Buck teeth” is the common term for a dental condition characterized by the forward protrusion of the upper front teeth beyond the lower teeth. This alignment issue is formally known as a malocclusion, meaning the upper and lower teeth do not meet correctly when the jaw is closed. Because the upper teeth stick out too far, this condition is one of the most frequent reasons people seek orthodontic care. The degree of this forward projection can vary widely, affecting both the appearance of the smile and the overall function of the mouth.
Defining Visual Characteristics
The defining visual characteristic of buck teeth is the horizontal distance between the upper and lower front teeth, a measurement dentists call an overjet. In a healthy bite, the upper incisors protrude horizontally past the lower incisors by only one to three millimeters. An overjet is diagnosed when this horizontal overlap exceeds the normal range, indicating a misalignment of the dental arches.
This excessive protrusion means the upper front teeth extend noticeably outward, often resting in front of the lower lip when the mouth is relaxed. In severe cases, the teeth may project outward by eight to ten millimeters or more. Visually, the upper jaw can appear far forward relative to the lower jaw.
The lower lip often rests behind the protruding upper teeth, which contributes to the characteristic appearance. This lack of support can give the lower lip a tucked-in look, while the upper teeth appear exposed and unprotected. The angle of the upper front teeth can also be tipped forward, or the entire upper jaw structure may be positioned too far ahead.
Skeletal and Habitual Factors
The development of buck teeth is typically due to a combination of inherited skeletal structure and environmental factors. Heredity plays a role, as the size and shape of the jaw are often passed down through generations. The condition often results from a mismatch in jaw size, such as an upper jaw positioned too far forward or a lower jaw that is too small. This foundational skeletal pattern dictates the underlying relationship between the dental arches.
Environmental or habitual factors also contribute by applying continuous force that gradually moves the teeth. Prolonged non-nutritive sucking behaviors, such as thumb or finger sucking and extended pacifier use, can push the developing upper teeth forward. If these habits continue past the age of three or four, the pressure exerted can permanently alter the angle at which the permanent teeth erupt.
Another common habitual cause is tongue thrusting, where the tongue presses against the back of the upper front teeth during swallowing or at rest. The repetitive force from the tongue slowly pushes the incisors outward over time. These environmental pressures work in conjunction with genetic predisposition to determine the final degree of protrusion.
Functional Considerations
Beyond the visual appearance, the excessive protrusion of buck teeth introduces several functional and health-related concerns. A primary risk is the increased susceptibility to dental trauma, such as chipped, fractured, or knocked-out teeth. Because the upper teeth project forward, they lack the protective cushioning of the lips, making them vulnerable to injury during falls or accidents. Correcting this protrusion can lower the risk of such injuries.
The misalignment can also lead to difficulty achieving complete lip closure, known as lip incompetence. This means the lips strain or cannot meet naturally when the jaw is relaxed. This often leads to chronic mouth breathing, which can dry out the mouth and affect oral health. The lack of proper alignment can interfere with the ability to bite into food effectively.
In some cases, the positioning of the teeth may affect speech articulation, potentially contributing to a lisp or difficulty pronouncing certain sounds. The jaw joint and surrounding muscles may also experience strain due to the improper bite, sometimes resulting in jaw pain or discomfort. Addressing the protrusion helps restore balance to both the appearance and the mechanical function of the mouth.