A dental cavity is a hole in a tooth resulting from tooth decay. This decay begins when bacteria convert sugars and starches into acids, which dissolve the hard outer layers of the tooth. These acids cause a loss of minerals from the enamel and dentin, creating plaque that accelerates the damage. A simple filling halts this cycle by removing the decayed material and sealing the tooth. Ignoring this initial problem allows the decay to progress through the tooth’s layers, transforming a minor issue into a major health concern.
The Initial Stages of Untreated Decay
When a cavity is left untreated, the decay rapidly breaches the enamel and penetrates the underlying dentin. Enamel is the hardest substance in the human body, but dentin is softer and more porous, accelerating the decay process. Dentin is composed of microscopic tubules that lead directly to the tooth’s internal nerve, or pulp.
As the decay moves into the dentin, the first noticeable symptom is increased tooth sensitivity. This discomfort manifests as a sharp, temporary pain when consuming hot or cold items, or even sweet foods. This sensitivity occurs because the exposed dentinal tubules allow external stimuli to irritate the pulp tissue. At this stage, a standard dental filling can effectively restore the tooth structure and prevent further progression.
Progression to Internal Nerve Infection
If the decay is not addressed, the bacterial infection eventually reaches the pulp chamber, the soft tissue at the tooth’s center. The pulp contains the tooth’s nerves, blood vessels, and connective tissue. When bacteria invade this space, it causes an inflammatory condition called pulpitis.
Pulpitis often results in severe, throbbing pain that is difficult to relieve, signaling nerve tissue infection. Since the pulp is encased within the rigid walls of the tooth, inflammation causes swelling that presses painfully on the nerves. Over time, the infection can overwhelm the blood supply, causing the nerve and blood vessels to die (necrosis). While necrosis may temporarily stop the pain, the infection remains, transforming the tooth into a dead, bacteria-filled conduit.
Spread of Infection and Structural Damage
Once the pulp tissue becomes necrotic, the bacteria continue to multiply, using the root canal system to exit the tooth’s tip. The immune system attempts to contain this infection, leading to a periapical abscess—a pus-filled pocket at the root’s end, often within the jawbone. Symptoms of an abscess include persistent pain, swelling in the jaw or face, and sometimes a small bump on the gums.
The chronic presence of this infection can destroy the bone supporting the tooth, leading to irreversible bone loss. In rare but serious instances, the infection can spread beyond the jawbone into the soft tissues of the face and neck, causing cellulitis. Bacteria from a dental infection can also enter the bloodstream and spread to other parts of the body, a condition known as sepsis.
Advanced Treatment Options and Costs
Allowing decay to progress to nerve involvement and abscess formation drastically changes the required treatment. When the nerve is infected, the tooth typically requires root canal therapy, which involves removing the infected pulp, disinfecting the internal chamber, and sealing it. Following a root canal, the tooth often needs a dental crown, a cap placed over the entire tooth to restore its strength and function.
If the tooth is too compromised or the infection is too severe, the only remaining option is extraction. Losing a tooth necessitates replacement to maintain proper bite alignment and function, usually through a dental bridge or a dental implant. A straightforward filling is dramatically less invasive and expensive than a root canal, crown, or extraction followed by an implant, which can easily cost thousands of dollars.