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 (often referred to as a 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 beneath the surface?
What Happens 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 primary goal is to contain the infection and prevent it from spreading further.
These cells act quickly in three main ways:
- Degranulation – Neutrophils release enzymes and antimicrobial substances that help damage and break down bacteria.
- Extracellular traps – Neutrophils release strands of DNA that form net-like structures. These act as sticky traps that capture and immobilize bacteria.
- Phagocytosis – Neutrophils engulf (“eat”) bacteria and break them down internally to destroy them.
Together, these processes represent the body’s attempt to control a rapidly progressing infection at the root of the tooth.
Why an Abscess Forms
After the immune response takes place, the area becomes filled with a mixture of dead bacteria, immune cells, tissue debris, and enzymes. This collection is what we commonly refer to as pus, which accumulates at the infection site.
The inflammatory byproducts within this area irritate the surrounding tissues, leading to a condition dentists call acute apical periodontitis. This is often responsible for the swelling, tenderness, and throbbing pain associated with a dental abscess.
Why Treatment Is Necessary
While the body’s immune system response is powerful, it is also a sign of a significant underlying infection. Without dental treatment, the infection will not resolve on its own and may continue to worsen or spread.
Professional care is required to remove the source of infection and protect both the tooth and surrounding bone structure.
The Bottom Line
Infections at the root of a tooth represent a complex battle between bacteria and the body’s immune defenses. Although your body works hard to contain the infection, dental intervention is essential to fully eliminate it and restore oral health.
If you are experiencing tooth pain, swelling, or discomfort when biting, schedule a dental evaluation as soon as possible with our team at Lynnfield Dental Associates to have your symptoms assessed and prevent the infection from progressing further.