The Battleground at the Root of an Infected Tooth

When a tooth becomes severely infected, bacteria can spread through the inner structure of the tooth and reach the tissues around the root. When this happens, it can lead to a painful infection at the tip of the root, known as a periapical lesion (or dental abscess).

At this stage, patients often experience significant discomfort. In addition to constant inflammation at the site, even light pressure—such as biting down—can cause sharp, intense pain. But what is actually happening here beneath the surface?

What’s Happening When the Infection Spreads

Once bacteria break through the bottom of the tooth and reach the surrounding tissues, the body responds immediately. The immune system sends a large number of defensive cells called neutrophils to the area. Their main goal is simple: contain the infection and prevent it from spreading further.

These cells act quickly and aggressively in three main ways:

• Degranulation – Neutrophils release substances containing enzymes that help break down and damage bacteria.
• Extracellular traps – Neutrophils release strands of DNA that form net-like structures. These act like sticky traps, capturing and immobilizing bacteria so they cannot spread.
• Phagocytosis – Neutrophils directly engulf (“eat”) bacteria and break them down inside the cell.

Together, these processes are the body’s way of trying to control a rapidly growing infection at the root of the tooth.

Why An Abscess Forms

Once the immune system has done its work, the area is left with a mixture of dead bacteria, immune cells, tissue debris, and enzymes. This buildup forms what is commonly known as pus, which collects at the infection site.

The presence of these enzymes and inflammatory byproducts irritates the surrounding tissues, which leads to a condition dentists refer to as acute apical periodontitis. This is often what causes the swelling, tenderness, and throbbing pain associated with a dental abscess.

Why Treatment Is Important

While the body’s immune response is powerful, it is also a sign that the infection has reached a serious stage. Without treatment, the infection will not resolve on its own and may continue to spread or worsen over time.

Dental treatment is necessary to remove the source of infection and prevent further damage to the tooth and surrounding bone.

The Bottom Line

Infections at the root of a tooth are the result of a complex battle between bacteria and the body’s immune system. While your body works hard to defend the area, professional dental care is essential to fully eliminate the infection and restore health.

If you are experiencing tooth pain, swelling, or discomfort when biting, schedule a dental evaluation as soon as possible with our team at Artisan Dentistry in Salem, NH or Newburyport, MA to have your symptoms assessed and prevent the infection from progressing further.