A wisdom tooth, officially known as the third molar, is the final molar in each corner of the mouth. These teeth are the last set to develop, typically emerging through the gums during the late teenage years or early twenties. Because all other permanent teeth are usually in place by this time, the third molars often encounter a dental arch that is already full. This late arrival means their eruption process can frequently be problematic, often resulting in growth at an abnormal angle.
Defining Impaction
The dental term for a wisdom tooth failing to emerge correctly is “impaction.” An impacted tooth is prevented from erupting into its functional position by another tooth, bone, or dense gum tissue. This condition is common, and classification is based on the angle of the tooth relative to the adjacent second molar.
Types of Impaction
The four primary classifications describe the direction of improper growth. Mesial impaction, the most common, means the tooth tilts forward toward the front of the mouth. Vertical impaction means the tooth is positioned upright but is trapped beneath the gum line. Distal impaction, the least common, occurs when the tooth is angled backward.
The most severe sideways growth is horizontal impaction, where the molar lies completely flat, pushing into the neighboring tooth. Impactions are also classified by depth: fully impacted means the tooth is entirely hidden beneath the gums and bone, or partially impacted means a portion of the crown has broken through the gum tissue.
Causes of Improper Growth
The primary reason wisdom teeth frequently grow improperly is a lack of space in the jaw. As the last teeth to develop, the third molars must contend with limited room remaining at the back of the dental arch. Modern human jaws are often smaller than those of our ancestors, leading to a crowded environment.
This discrepancy between jaw size and tooth size means there is often insufficient room for the third molars to erupt cleanly. Instead, they become blocked by the bone or the second molar already in place. Genetic factors also play a part, as the size and shape of the jaw and teeth are inherited traits, predisposing some individuals to impaction.
Effects on Oral Health
Impacted wisdom teeth can lead to specific complications affecting the surrounding oral environment. Pressure from a horizontally or mesially impacted tooth pushing against the second molar can damage the adjacent tooth’s root or crown. This pressure may also lead to erosion of the second molar’s root surface, threatening its stability. Furthermore, the odd angle of emergence creates a partially exposed tooth that is difficult to clean.
This partially exposed tooth creates a small pocket under the gum tissue where food particles and bacteria become trapped. This accumulation leads to pericoronitis, which is an infection and inflammation of the gum flap covering the tooth. Symptoms include localized pain, swelling, foul taste, or bad breath. Severe infection can cause difficulty in opening the mouth or swallowing.
Impacted wisdom teeth can also contribute to the formation of cysts or tumors within the jawbone. The tissue sac surrounding the developing tooth can fill with fluid, forming a cyst that expands and destroys surrounding bone tissue. These growths can cause significant structural damage to the jawbone, nerves, and adjacent teeth if left unaddressed. Even asymptomatic impacted teeth can harbor issues like decay or gum disease that progress silently.
Extraction and Management
Management begins with a diagnostic process, often before symptoms appear. Dental X-rays, particularly panoramic images, visualize the position of the third molars relative to the jawbone and neighboring teeth. These images allow a dental professional to determine the exact angle and depth of impaction, informing the decision to monitor or remove the teeth.
Extraction is based on symptomatic necessity or prophylactic prevention. Removal is necessary if the tooth is causing active disease, such as pain, recurrent infection, or damage to the adjacent tooth. Prophylactic extraction is sometimes recommended in younger patients to avoid later problems, as surgery and healing are easier when root formation is incomplete. The procedure is typically performed as an outpatient surgery under local anesthesia, sedation, or general anesthesia.
A surgical extraction requires the surgeon to make an incision to expose the tooth and any overlying bone. The tooth may need to be divided into smaller sections for easier removal, and the site is often closed with dissolvable stitches. Recovery involves initial swelling and discomfort, managed with prescribed pain medication and cold compresses. Patients are advised to rest, avoid strenuous activity, and maintain a soft diet for several days to promote clot formation.