The wisdom teeth are the last set of teeth to develop, emerging in the late teenage years or early twenties. Because the jaw often lacks sufficient space, these molars frequently become impacted, trapped beneath the gum line or bone. This positioning causes the wisdom tooth to exert sustained pressure against the adjacent second molar. This force can compromise the second molar’s structure, making it highly susceptible to cracks and fractures.
The Mechanics of Impaction and Pressure
The physical process that leads to damage begins when the third molar attempts to erupt into an already crowded dental arch. The direction and angle of the impaction determine the specific force applied to the second molar. The most common types of impaction are mesioangular and horizontal, where the wisdom tooth is tilted forward or lying completely on its side, pressing directly against the back of the second molar.
In these orientations, the crown or root of the impacted tooth applies a chronic, steady mechanical force to the distal (back) surface of the second molar. This force is a constant, low-grade push that stresses the adjacent tooth structure over months or years.
Structural Damage to the Adjacent Molar
The chronic pressure from an impacted third molar often results in a condition known as external root resorption (ERR) on the second molar. Resorption is a pathological process where the tooth’s root structure is gradually dissolved or worn away. This process typically occurs on the distal root surface of the second molar, directly where the wisdom tooth makes contact.
Even slight resorption can compromise the integrity of the second molar’s root, creating a defect that weakens the overall tooth. This weakened root structure is then far less resistant to the normal forces of chewing and biting. A tooth compromised by root resorption is much more likely to develop a vertical or oblique fracture extending from the crown down into the root, which is a severe form of structural damage.
Recognizing the Symptoms of Molar Damage
Damage to the second molar caused by an impacted wisdom tooth may initially be asymptomatic, especially when the damage is limited to early root resorption below the gum line. When symptoms do appear, they often mimic other dental problems, making diagnosis difficult without imaging. Patients may notice sharp pain when biting down or chewing, particularly on hard foods.
Increased sensitivity to hot or cold temperatures is also a common indicator that the internal structure, such as the pulp, has been affected. The pain might be intermittent, occurring only when pressure is applied or relieved, which is a classic sign of a cracked tooth. Because these symptoms can be vague, a professional dental examination and diagnostic imaging, such as an X-ray or Cone Beam Computed Tomography (CBCT), are needed to definitively assess the second molar’s condition.
Treatment and Preventative Measures
Once structural damage or a high risk of damage is identified, the primary step is the extraction of the problematic wisdom tooth. Removing the source of the pressure immediately halts the destructive mechanical force and prevents further root resorption. This extraction is a preventative measure for the second molar, even if no severe damage has yet occurred.
If the second molar has only minor damage, such as shallow resorption or a small crack, it may be treated with restorative procedures like a filling or a full crown. However, if the root resorption has progressed significantly, potentially invading the pulp, the tooth may require a root canal procedure to save it. In the most severe cases of deep fracture or extensive root damage, the second molar itself may need to be extracted, necessitating the loss of two molars. Proactive monitoring through regular dental checkups and X-rays allows for early intervention, ideally before the second molar is compromised.