A deep bite, also known as an excessive overbite, is a common form of malocclusion where the upper front teeth significantly overlap the lower front teeth when the jaw is closed. While a small amount of vertical overlap is normal, a deep bite represents a deviation from this ideal alignment. Severity varies greatly, ranging from a slight increase in overlap to cases where the lower teeth are completely hidden, sometimes contacting the gum tissue behind the upper teeth.
Identifying an Excessive Overbite
An overbite describes the vertical overlap of the upper front teeth over the lower front teeth when the back teeth are together. In an ideal bite, the upper incisors should cover approximately 20 to 40% of the height of the lower incisors, corresponding to about 1 to 3 millimeters of overlap.
A deep bite is diagnosed when this vertical overlap exceeds the normal range, typically covering more than 50% of the lower teeth, or more than 4 millimeters. Orthodontists classify bites as deep if the overlap is between 4 and 8 millimeters, and severe if it measures 9 millimeters or more. This condition can be primarily dental, relating only to the position of the teeth, or skeletal, involving a discrepancy in the size or position of the jawbones.
Health Consequences of Untreated Deep Bites
Untreated excessive overbites can lead to physical problems that extend beyond cosmetic concerns. One immediate mechanical issue is excessive wear and tear on the teeth. The lower front teeth often bite directly into the back surface of the upper front teeth, leading to premature enamel erosion and potential damage to the tooth structure. This friction increases the risk of sensitivity and decay.
Damage to the soft tissues is another serious outcome, particularly in severe cases. The lower front teeth can impinge upon the gum tissue behind the upper front teeth, causing chronic irritation, inflammation, and gingival recession. Conversely, the upper front teeth may traumatize the gums of the lower arch, leading to similar periodontal issues.
A deep bite often forces the lower jaw into an unnatural position, straining the temporomandibular joints (TMJ) and surrounding muscles. This misalignment contributes to temporomandibular joint disorders (TMD), which can cause chronic jaw pain, headaches, clicking sounds, and difficulty chewing.
Determining When Correction is Necessary
Correction is not necessary for every person with a deep bite, particularly in mild cases that do not present functional problems. Intervention is medically appropriate when the condition poses a clear risk of damage or is already causing functional impairment. Orthodontists use specific criteria to determine the necessity of treatment, focusing on evidence of physical harm.
Correction is a priority if there is existing dental or gum trauma, such as visible wear on the enamel of the lower teeth or signs of soft tissue impingement. Orthodontists perform a risk assessment, evaluating the potential for future damage if the bite is left untreated. Overlaps greater than 40% are often considered excessive due to their potential to cause deleterious effects on dental health and the TMJ. Treatment is often more straightforward and effective during the growth phases in younger patients, as jaw development can be guided to help level the bite.
Orthodontic Approaches to Deep Bite Correction
Deep bite correction fundamentally aims to level the bite plane, typically achieved by a combination of movements: intruding (pushing up) the front teeth and extruding (pulling down) the back teeth. Traditional braces are a common and effective method, using archwires and brackets to apply continuous force to shift the teeth into their correct vertical positions. Specialized components like bite pads or bite turbos are often used early in treatment to momentarily separate the bite and protect the lower brackets.
Clear aligner systems can also correct deep bites, utilizing specific techniques such as pressure-transmitting attachments and bite ramps placed on the upper anterior teeth. These ramps help disengage the back teeth, allowing them to move into a better position while applying an intrusive force to the front teeth. In younger patients, removable appliances like specialized bite plates may be employed to guide jaw growth and eruption patterns. For the most severe skeletal deep bites in adults, where the jaw structure is significantly misaligned, orthognathic surgery may be the necessary route to achieve a stable and functional correction.