An overbite describes the vertical overlap of your upper front teeth over your lower front teeth when your mouth is closed. It is a common dental characteristic, not inherently a problem, and exists in varying degrees among most individuals. This overlap plays a role in how teeth align and function.
Understanding Overbite Measurement
Overbite is typically measured as a percentage or in millimeters. A percentage indicates how much of the lower front teeth are covered by the upper front teeth. For example, a 50% overbite means half of the lower incisor is hidden by the upper incisor when teeth are in full contact. Millimeter measurements quantify the vertical distance of this overlap. Both methods provide a clear metric for evaluation.
Defining the Normal Range
A healthy overbite is a natural and functional aspect of dental alignment, allowing for proper chewing, speech, and protection of the lower teeth. The normal range for vertical overbite is considered to be between 25% and 50% coverage of the lower teeth by the upper teeth. In terms of millimeters, this translates to an overlap of 2 to 4 millimeters. This specific range is beneficial because it enables efficient biting and chewing without undue stress on the jaw joints or excessive wear on the teeth. A normal overbite ensures the lower front teeth lightly contact the back of the upper front teeth, promoting stability and proper function.
Beyond the Normal: Types and Implications of Overbite
When the overbite falls outside the normal range, it can lead to various dental and functional concerns.
Deep Overbite
A deep overbite, also known as an excessive overbite, occurs when the upper teeth cover more than 50% of the lower teeth, or the overlap exceeds 4 millimeters. In severe cases, the lower front teeth can bite into the gum tissue behind the upper front teeth, causing irritation, damage, and potential gum recession. A deep overbite can also result in excessive wear on the lower front teeth, jaw pain, headaches, and difficulties with chewing or speech.
Insufficient Overlap
Insufficient overlap can also present issues, such as an open bite or an edge-to-edge bite. An open bite occurs when the upper and lower teeth do not meet at all, leaving a noticeable gap even when the mouth is closed. This condition can make it challenging to bite certain foods, lead to speech difficulties, and cause excessive wear on teeth that do make contact, often the molars. An edge-to-edge bite, a specific type of malocclusion, occurs when the upper and lower front teeth meet directly at their biting edges without vertical overlap. This direct contact can lead to increased tooth wear, chipping, fractures, and jaw pain due to uneven pressure distribution.