The observation that lower teeth appear suddenly longer is a common concern that rarely means the teeth are actually growing. Human teeth stop growing in adulthood, meaning any perceived increase in length is an illusion caused by changes to the surrounding oral structures. This visual change is primarily the result of soft tissue migration or mechanical wear, each of which affects the visible portion of the tooth crown or root. Understanding the specific cause is the first step toward protecting the health and appearance of the lower front teeth.
Gum Recession: Exposing the Root
The most frequent reason for teeth appearing longer is the movement of the gum tissue away from the tooth’s surface, known as gum recession. The gum line normally covers and protects the tooth root, but when it pulls back, the root’s surface becomes exposed and visible. This exposure makes the entire tooth look elongated.
A major cause of this recession is mechanical trauma, frequently resulting from aggressive horizontal brushing or using a hard-bristled toothbrush. Another significant factor is periodontal disease, a bacterial infection that causes inflammation and gradual destruction of the supporting bone structure. As the underlying bone is lost, the gum tissue naturally follows the bone level, moving down to expose the root.
Bite Misalignment and Differential Wear
Another mechanism that contributes to the altered appearance of tooth length involves mechanical forces and the way the upper and lower teeth meet, known as occlusion. In cases of a deep overbite, the upper front teeth significantly overlap the lower front teeth vertically. This excessive overlap can cause the biting edges of the lower teeth to continually scrape against the gum tissue or the back surfaces of the upper teeth.
This constant friction leads to premature wear, or abrasion, on the enamel of the upper teeth, making them shorter over time. Conversely, the lower teeth may be subject to a process called “super-eruption,” or they may simply look more prominent and longer because the upper teeth, which normally conceal them, have worn down. Misalignment or crowding can also place undue force on certain teeth, contributing to localized recession.
Why Increased Length Matters
The appearance of increased tooth length is not just a cosmetic issue; it signals that the protective anatomy of the tooth has been compromised. The root surface, visible due to recession, is covered in cementum, which is much softer than the enamel covering the crown. This softer material is highly susceptible to root decay, increasing the risk of cavities below the normal gum line.
The dentin within the root contains channels called dentinal tubules that lead directly to the tooth’s nerve. When the gum tissue and cementum are gone, external stimuli like hot, cold, or sweet foods can travel through these exposed tubules, causing tooth sensitivity. If the underlying issue is advanced periodontal disease, the long-term risk includes bone support loss, which can lead to tooth mobility and eventual tooth loss.
Treatment and Prevention Strategies
Addressing the underlying causes of the perceived increased tooth length requires both professional intervention and changes to daily habits.
Professional Treatment
For cases caused by tissue loss, professional treatments include soft tissue grafting, where tissue is surgically placed to cover the exposed root surface. Dental bonding or composite resin can also be applied to the exposed root to mask the length and create a protected surface. If the cause is bite-related, orthodontic treatment, such as braces or clear aligners, can correct the misalignment and reduce the excessive vertical overlap causing wear.
Prevention
To stop further progression, prevention centers on modifying oral hygiene habits. This involves switching to a soft-bristled brush and using a gentle, rolling motion instead of aggressive horizontal scrubbing. For patients who grind their teeth, a custom nightguard is often recommended to cushion the bite and protect the tooth structure.