A cavity, known scientifically as dental caries, represents permanent damage to the hard structure of a tooth. This damage begins when bacteria in the mouth convert sugars from food and drink into acid, which dissolves the tooth’s protective layers. This acidic attack leads to tiny holes in the tooth’s surface that progressively enlarge over time. If left unaddressed, this decay moves through a series of increasingly severe stages, revealing why timely intervention is important for long-term health.
Early Deterioration of the Tooth Structure
The first stage of decay involves the enamel, which initially undergoes demineralization. This process often manifests as a chalky white spot on the tooth surface, indicating that minerals are being lost faster than they can be naturally replaced. During this phase, the condition is frequently asymptomatic, meaning the person feels no pain or sensitivity. However, the enamel barrier is slowly compromised, making the decay difficult to reverse without professional intervention.
Once bacteria breach the enamel and reach the underlying dentin, the rate of decay accelerates dramatically. Dentin is softer and contains microscopic tubules leading toward the tooth’s center. When decay enters this layer, the tooth may begin to exhibit sensitivity to hot, cold, or sweet stimuli. Because dentin provides less resistance than enamel, the bacterial infection advances rapidly toward the inner structures of the tooth.
Infection Reaching the Tooth’s Nerve Center
The dentin layer is the last defense before infection reaches the pulp chamber, the innermost part of the tooth housing the nerves and blood vessels. When bacteria invade this soft tissue, the resulting inflammation is called pulpitis. Since the inflamed pulp is encased in the rigid tooth structure, the swelling creates intense pressure on the nerves and blood supply.
This pressure results in a throbbing, continuous toothache that lingers after exposure to temperature stimuli, known as irreversible pulpitis. If the pressure becomes too great, it constricts the blood vessels, causing the nerve to die (necrosis). This nerve death can lead to a temporary relief of severe pain, creating a dangerous “silent phase” that suggests the problem has resolved.
The absence of pain does not mean the infection is gone. The necrotic pulp tissue remains within the root canal system, acting as a breeding ground for bacteria. These microbes and their toxins multiply and travel down the tooth’s root, poised to exit the tooth structure and contaminate the surrounding bone and soft tissue.
Formation of Severe Localized Infection
Once the infection travels through the end of the tooth root and into the jawbone, the immune system attempts to contain the bacteria. This reaction results in a periapical abscess, a pocket of pus composed of dead cells and bacteria. The abscess creates swelling and severe tenderness, especially when pressure is applied during chewing.
The chronic inflammation triggers the body to resorb the surrounding jawbone tissue, leading to localized bone loss around the tooth root. Pressure from the accumulating pus may force a path outward through the bone and gum tissue, creating a small bump called a fistula or gum boil. This drainage route temporarily relieves pressure and discomfort.
Failure to manage the abscess compromises the structural integrity of the tooth, making it susceptible to fracture. The infection is not always contained and can spread to adjacent teeth or surrounding structures like the jaw and the floor of the mouth. At this point, the infection moves beyond a simple cavity.
Potential Impact on Overall Body Health
The localized infection within the jawbone serves as a reservoir of bacteria that can enter the bloodstream and spread throughout the body. A rapidly spreading infection from a dental abscess can lead to cellulitis, a severe soft tissue infection causing dangerous swelling in the face or neck. In rare cases, bacteria from an upper tooth can travel to the brain, causing a brain abscess or cavernous sinus thrombosis.
Chronic oral infection contributes to systemic inflammation, which is linked to the exacerbation of various non-oral health conditions. For example, untreated infection makes it challenging to manage blood sugar levels in individuals with diabetes. Chronic dental infections are also associated with increased risk factors for cardiovascular disease, including the narrowing of arteries.