Though overjet and overbite may sound similar, they are distinct conditions involving different types of misalignments. While both affect the relationship between the upper and lower teeth, the key difference lies in the direction and nature of the misalignment.
What is an overjet?
An overjet is a type of malocclusion, or misalignment, where the upper front teeth stick out farther than they should.1 This occurs when the upper teeth protrude outward and sit over the lower teeth, often giving the appearance of “buck teeth.2
What is an overbite?
An overbite, sometimes called a “deep bite,” occurs when your upper front teeth overlap your lower front teeth more than they should.1 A small overbite is normal, with an overlap of 2 to 4 millimeters.1 However, when your upper teeth cover more than 30% of your lower teeth, or about 4 to 6 millimeters, it is considered an overbite.1
Key differences between overjet and overbite
The key difference between overjet and overbite lies in the direction of the misalignment. Overjet refers to a horizontal misalignment where the upper teeth protrude diagonally beyond the lower front teeth.3 In contrast, overbite is a vertical misalignment, where the upper teeth overlap the lower teeth more than what is typical.3
In both conditions, the upper teeth protrude over or in front of the lower teeth.4 However, with an overjet, the upper teeth extend past the lower teeth at an angle, while with an overbite, the upper teeth simply overlap the lower teeth in a straight or downward position without any angle.4
Causes of overjet and overbite
Overjet and overbite are both types of malocclusions, but they develop for different reasons. Understanding the specific causes of each condition can help identify the best approach for treatment.
Causes of overjet
An overjet can be caused by several factors. Some of the most common causes include:
Genetics: An overjet can be passed down from your parents, often due to the size or shape of the jaw.5
Underdeveloped lower jawbone: A smaller lower jaw can result in the upper teeth protruding.5
Poor oral habits: Thumb sucking, tongue thrusting, and overuse of pacifiers during childhood can contribute to an overjet.5
Causes of overbite
Several factors can contribute to the development of an overbite. These often involve habits or behaviors that put pressure on the teeth and jaw over time, such as:
Excessive nail biting: Repeatedly biting your nails can affect the alignment of your teeth.3
Teeth grinding (bruxism): Clenching or grinding your teeth, especially at night, may cause an overbite to develop or worsen.3
Tongue-thrusting: This occurs when your tongue presses too far forward against your teeth, influencing their position.3
Thumb-sucking or pacifier use: Prolonged use of pacifiers or thumb-sucking habits beyond age three can lead to misalignments, including an overbite.3
