Many people question whether their bite is aligned correctly, often based on the visual appearance of their front teeth. Occlusion, or how the upper and lower teeth meet, involves a complex relationship between teeth, jaws, and muscles. Confusion often arises between a normal overlap and a problematic misalignment. To understand what constitutes a healthy bite, it is important to first clarify the specific terms used by dental professionals.
Defining Dental Terminology
The term “occlusion” describes the physical contact between the teeth of the upper and lower jaws when the mouth is closed. A healthy occlusion allows for efficient chewing and speaking while protecting the soft tissues of the mouth. When the bite is misaligned, it is referred to as a malocclusion.
The public often uses “overbite” to describe any protrusion of the upper teeth, but dental professionals distinguish between two measurements. Overbite, technically known as vertical overlap, is the extent to which the upper front teeth cover the lower front teeth vertically. This measurement is typically expressed in millimeters or as a percentage of the lower tooth crown height.
Overjet refers to the horizontal protrusion, which is the distance between the upper and lower front teeth in the horizontal plane. Overjet is what people often mean when they describe “buck teeth.” Understanding this difference is important, as excessive vertical overlap (overbite) and excessive horizontal protrusion (overjet) can occur independently or together.
The Ideal Bite: The Standard for Vertical Overlap
A slight overbite is acceptable and is considered the standard for a healthy, functional bite, known as Class I occlusion. This small degree of vertical overlap is necessary for the front teeth to properly shear food and protect the gum tissue of the lower jaw. The upper teeth act as a protective shield for the lower arch.
For most adults, the ideal vertical overlap is approximately 1 to 3 millimeters when the back teeth are closed. Measured as a percentage of the lower incisor’s height, this range corresponds to the upper teeth covering about 20% to 30% of the lower teeth. The lower front teeth should lightly touch the back surface of the upper front teeth for optimal function.
This slight overlap provides stability to the bite, allowing the upper and lower arches to function in harmony without excessive wear. A healthy overbite ensures that chewing forces are distributed correctly across all teeth, supporting the long-term health of the jaw joints. If the overlap is less than this range, or there is no overlap at all, it can lead to an open bite, which is a different form of malocclusion.
When Vertical Overlap Becomes a Malocclusion
The slight overlap transitions into a malocclusion when vertical coverage exceeds the accepted standard, resulting in a condition called a deep bite or excessive overbite. This problem is diagnosed when the upper teeth cover more than 50% of the height of the lower front teeth. A deep bite is defined as an overlap greater than 4 millimeters.
This excessive vertical overlap can lead to several complications beyond aesthetics. A deep bite can cause the lower front teeth to bite directly into the gum tissue behind the upper front teeth, leading to chronic irritation and damage. Conversely, the upper teeth may wear down the front surfaces of the lower teeth at an accelerated rate.
The constant, abnormal contact caused by a deep bite can also affect the temporomandibular joints (TMJ), potentially leading to pain or dysfunction. The causes of a deep bite can be skeletal, involving a discrepancy in the size or position of the upper and lower jaws, or dental, caused by the over-eruption of the front teeth or the under-eruption of the back teeth.
Corrective Measures for Excessive Overbite
Treatment for an excessive overbite depends on the underlying cause, whether it is dental (tooth position) or skeletal (jaw size). For cases that are mainly dental, standard orthodontic treatments are effective. Traditional metal braces and clear aligners are used to precisely move the teeth into a healthier alignment.
These methods adjust the vertical dimension of the bite. This often involves “intruding” the upper or lower front teeth, pushing them slightly back into the jawbone, or “extruding” the back teeth to open the bite in the front. Functional appliances, like the Herbst appliance, are sometimes used in growing patients to encourage the forward growth of the lower jaw.
For severe skeletal discrepancies, where the jawbones are significantly misaligned, a combination of orthodontics and orthognathic surgery may be necessary. Jaw surgery is performed by an oral and maxillofacial surgeon to physically reposition the upper and/or lower jaw to achieve proper alignment. This approach is reserved for complex cases to ensure a stable, functional, and healthy bite.