A wisdom tooth is usually the last type of tooth to erupt in the mouth and thus has a narrow amount of space to grow into. When a wisdom tooth starts erupting out of position, the tooth is impacted. There are different types of impaction, but one of the most common types is a mesial impaction, which happens when the tooth starts to grow in tilted too far forwards.
A mesial impaction doesn't necessarily require extracting the wisdom tooth. But the impaction can lead to some complications that might make an extraction a good idea.
The mesial impacted tooth trajectory means that the tooth will start to press against the molar that is already in the rear of your mouth. If the impacted tooth continues on its course, the pressure of the erupting tooth can start to shift the existing molar out of place. The shift can cause bite issues or crowding if the tooth shifts past the tooth ahead of it.
This potential shifting is especially risky if you are missing a tooth on that side of your mouth. The shifting can start a chain reaction that can cause the teeth to all shift out of position, which may cause such severe bite issues that orthodontics might be required.
Pericoronitis is a soft tissue infection that can occur over the partially erupted mesial impacted tooth. The partial eruption leaves a skin flap in the area of the tooth, which can collect bacteria that form the infection. The tissue can become painful, swollen, and start to emit a foul-smelling discharge.
Your dentist can treat pericoronitis with antibiotics and saline rinses. But if the flap remains—meaning, the tooth never fully erupts—there's a high chance of recurrence. If you have already had recurring infections, your dentist might want to schedule a wisdom tooth extraction.
The wisdom tooth erupts through a hollow cavity or sac that travels through the jawbone and gums. If the tooth fails to erupt properly, this passageway is vulnerable to fluid buildups that can create a cyst. This cyst can cause symptoms similar to a soft tissue infection, but the infectious material can also start to eat away at the gums and jawbone. Left untreated, the material can open a new passageway called a fistula and travel elsewhere in the body.
Cysts can be lanced and treated with both oral and topical antibiotics. Your dentist might also want to remove the tooth, especially if a fistula has already started to form. The dentist can fill in the fistula with a tissue or bone graft, depending on the nature and severity of the damage.