A cavity is a hole in the tooth structure caused by acid erosion from bacteria. Bacteria in the mouth consume sugars and starches, producing acids that slowly dissolve the hard outer layer of the tooth, the enamel. Delaying treatment allows this decay process to continue unchecked, transforming a minor dental issue into a serious medical concern. The consequences progress through distinct, worsening stages that affect the tooth and potentially your overall health. This article details the progression of damage that occurs when a cavity is not filled.
The Initial Deepening of Decay
When a cavity first forms in the hard enamel layer, it often causes no pain because enamel contains no nerves. If left untreated, bacterial acids will eventually burn through the enamel and expose the underlying layer known as dentin. Dentin is softer and less mineralized than enamel, making it far more vulnerable to rapid decay once it is reached.
Dentin is composed of millions of microscopic tubules that connect directly to the inner pulp chamber of the tooth. Once the decay enters the dentin, you begin to experience tooth sensitivity, especially to hot, cold, or sugary foods and drinks. The decay accelerates significantly because dentin is less resistant, allowing the cavity to deepen much faster toward the tooth’s nerve center.
When Decay Reaches the Nerve
The decay continues its progression until it breaches the dentin and enters the pulp chamber, which houses the blood vessels and nerves. When bacteria reach this soft tissue, they cause inflammation known as pulpitis. This inflammation inside the rigid tooth structure presses on the nerve, causing severe, persistent, throbbing pain that can radiate into the jaw or face.
The pain is often acute and may worsen significantly when lying down or at night. The infected pulp tissue will begin to die, a process called necrosis. The death of the nerve may temporarily stop the pain, which can mislead a person into thinking the problem has resolved. However, the infection remains, and the tooth is now a dead, infected space allowing bacteria to proliferate.
The Development of Infection and Abscess
The bacterial infection from the necrotic pulp travels through the root canals and exits the tip of the tooth root, spreading into the surrounding bone and tissue. The body’s immune response attempts to contain this infection, resulting in the formation of a periapical abscess, a concentrated pocket of pus at the root tip. This localized buildup causes significant pressure, leading to intense, localized pain and facial swelling.
Symptoms include tenderness when biting down, swelling in the cheek or jaw, and sometimes a foul taste if the abscess drains. The infection also begins to destroy the jawbone supporting the tooth, causing bone loss around the root. At this advanced point, a simple filling is no longer adequate. The tooth requires either root canal therapy to clean out the infected pulp and canals or, if the damage is too extensive, extraction.
Spreading Infection and Tooth Loss
If the abscess is ignored, the infection can spread into the soft tissues of the face and neck, a condition known as cellulitis. This rapidly spreading infection can cause massive swelling and may obstruct the airway, making it difficult to swallow or breathe. This is a life-threatening medical emergency.
The bacteria can also enter the bloodstream, leading to sepsis, a systemic inflammatory response that can cause widespread organ damage and even death. Although rare, a severe infection from an upper back tooth can spread to the sinuses or the brain. Ultimately, the tooth becomes non-restorable due to structural breakdown and bone loss, necessitating extraction. The loss of the tooth then leads to further issues, including shifting of adjacent teeth, collapse of the bite, and atrophy of the jawbone.