Wisdom teeth, or third molars, are the final set of teeth to develop, typically emerging in the late teens or early twenties. Impaction occurs when there is insufficient space for the tooth to fully erupt into a functional position. A horizontal impaction is one of the most mechanically complex orientations, as the tooth grows completely sideways. Due to the high risk of damage to adjacent teeth and surrounding structures, surgical removal is often the recommended course of action.
Understanding Horizontal Impaction
A horizontal impaction is defined by the wisdom tooth growing completely sideways, or perpendicular, to the adjacent second molar. The tooth is essentially lying down within the jawbone, placing its crown directly against the roots of the second molar. This orientation creates an immediate and continuous point of pressure.
Diagnosis is usually achieved through dental imaging, most commonly a panoramic X-ray (Panorex). This image helps determine the exact angle and depth of the impacted tooth. In complex situations, especially near the mandibular nerve canal, a three-dimensional Cone Beam Computed Tomography (CBCT) scan may be used. This advanced imaging allows the surgeon to precisely map the tooth’s relationship to surrounding nerves and bone for surgical planning.
The mechanical problem created by this sideways growth is significant because the tooth cannot erupt past the second molar. As the root structure develops, the pressure exerted by the horizontal tooth can lead to a cascade of problems. This physical blockage requires a surgical approach that differs substantially from the removal of an erupted molar.
Criteria for Mandatory Extraction
The decision to remove a horizontally impacted wisdom tooth often becomes necessary to address current or impending pathology. Immediate concerns include evidence of pathology, such as pericoronitis (infection of the gum tissue) or deep decay in the wisdom tooth or adjacent second molar, as the tight space makes cleaning impossible.
Physical damage to the second molar is a strong justification for mandatory extraction. Constant pressure from the horizontal tooth can cause external root resorption, where the root structure of the healthy second molar is slowly worn away. This damage compromises the stability and long-term health of the functional tooth, potentially leading to its premature loss.
Another element is the follicular sac surrounding the wisdom tooth, which can fill with fluid and expand to form a follicular cyst. These cysts destroy surrounding jawbone and shift the position of other teeth. When a horizontal impaction is associated with uncontrolled pain, persistent infection, or structural damage, immediate removal is required. Early removal is frequently recommended even in asymptomatic cases to prevent these irreversible complications.
Risks of Retaining Impacted Teeth
Choosing to monitor an asymptomatic horizontal wisdom tooth carries a significant risk of future complications. The tight space between the third molar and the second molar creates a long-term hygiene challenge. Food debris and bacteria easily accumulate in this inaccessible area, making the second molar highly susceptible to chronic decay, often starting near the bone line.
The chronic presence of bacteria can also trigger a low-grade periodontal infection that slowly erodes the bone supporting the second molar. This bone loss is irreversible and weakens the support structure of the dentition in that area. Allowing the horizontal tooth to remain increases the likelihood that its eventual removal will be more complex and require treatment for the secondary damage it has caused.
What to Expect During Surgery and Recovery
The removal of a horizontally impacted wisdom tooth is a specialized surgical procedure typically performed by an oral and maxillofacial surgeon. Since the tooth is completely encased in bone and lying on its side, the surgeon must first make an incision in the gum tissue to gain access. A small amount of the bone surrounding the tooth is then carefully removed using a surgical drill to fully expose the crown.
The horizontally positioned tooth cannot be pulled out whole and must be cut into smaller pieces, a technique known as sectioning. The crown is typically separated from the roots and removed first, followed by the roots. This sectioning minimizes the force required for removal, reducing trauma to the surrounding bone and the adjacent second molar.
Anesthesia options range from local anesthesia, where the patient remains awake, to intravenous (IV) sedation, which induces a relaxed semi-consciousness. General anesthesia is also an option for complex cases or patients with high anxiety. After the tooth is removed and the socket is cleaned, the gum tissue is sutured closed, often with dissolvable stitches.
Recovery requires diligent post-operative care to manage swelling, pain, and prevent dry socket. Swelling is managed by applying ice packs to the cheek for 20 minutes on and 20 minutes off for the first 24 to 48 hours. Pain is controlled with prescribed or over-the-counter medication, which should be taken as directed.
To prevent dry socket, which occurs when the protective blood clot is dislodged, patients must avoid creating suction in the mouth. This means refraining from using straws or smoking for at least one week. A soft-food diet is required for several days, and patients should avoid spitting or vigorous rinsing. Starting 24 hours after surgery, gentle rinsing with warm salt water can help keep the area clean and promote healing.