Tooth decay (dental caries) is a progressive disease initiated by bacteria that colonize the mouth and metabolize dietary sugars. These bacteria produce acids that erode the tooth structure, forming a cavity over time. While the initial decay may seem minor, failing to treat a decayed tooth sets in motion an unavoidable sequence of escalating damage. Neglecting this condition transitions the problem from a simple dental issue to a significant threat to overall health.
Progression of Cavity and Increased Pain
Tooth decay begins by demineralizing the enamel, the tooth’s outer protective layer. This initial stage, often appearing as a chalky white spot, is typically painless because enamel lacks nerve endings. If the acid continues to dissolve the mineral structure, a cavity forms, marking the first structural breach.
Once decay penetrates the enamel, it reaches the dentin, the softer layer beneath the surface. Dentin contains microscopic channels called tubules, which lead toward the tooth’s inner pulp chamber. Because dentin is less mineralized and more porous than enamel, bacteria spread much faster once they reach this layer.
The exposure of these dentinal tubules causes a noticeable increase in tooth sensitivity. Individuals often experience sharp, fleeting pain when consuming hot or cold beverages or sugary foods. This sensitivity signals that the decay is advancing toward the nerve tissue housed deep inside the tooth structure.
Internal Infection and Abscess Formation
As decay spreads through the dentin, bacteria eventually breach the pulp chamber wall, the soft tissue core of the tooth. The pulp contains nerves, blood vessels, and connective tissue, making it highly vulnerable to infection. The resulting inflammation is known as pulpitis.
The influx of bacteria creates pressure within the rigid pulp chamber walls, leading to intense, sustained pain that may throb or radiate. This pressure restricts blood flow, causing the nerve and blood vessels to die, a condition called necrosis. Once the pulp is necrotic, the pain may temporarily subside, but the infection remains and worsens.
The bacteria then travel down the root canals, exiting the tooth’s tip into the surrounding jawbone. The immune system attempts to contain the infection, resulting in a periapical abscess—a localized pocket of pus at the root end. An abscess requires immediate intervention, such as a root canal procedure or, if damage is too extensive, a tooth extraction.
Spread of Infection to Jaw and Body
Leaving a periapical abscess untreated allows the infection to break out of its localized pocket and spread into adjacent anatomical spaces. Locally, the infection can erode the surrounding jawbone, a condition called osteomyelitis. It can also cause cellulitis, a rapidly spreading bacterial infection of the soft tissues of the face and neck.
If the infection descends into the neck’s deep fascial spaces, it can lead to Ludwig’s angina. This severe form of cellulitis causes massive swelling and can obstruct the airway, requiring immediate medical intervention.
The bacteria can also enter the bloodstream, a process known as bacteremia, which may progress to life-threatening septicemia, or sepsis. Infectious agents are carried via the blood to distant organs, creating secondary infections. This systemic spread poses a danger to the heart, where bacteria can settle on damaged heart valves or tissue, causing infective endocarditis.
In serious cases, the infection may travel upward, leading to a brain abscess or cavernous sinus thrombosis. These complications elevate the dental problem to a medical emergency requiring hospitalization and intensive treatment. The systemic movement of oral bacteria demonstrates that an unaddressed decayed tooth is a potential source of severe, non-local disease.