A cavity, clinically known as dental caries, is a breakdown of the tooth structure caused by bacteria that convert sugars into acids. This acid steadily erodes the tooth material, creating a hole that will only enlarge if neglected. Ignoring a cavity allows this destructive process to progress through multiple layers of the tooth, leading to increasingly severe pain, deep infection, and potentially serious health complications beyond the mouth.
Progression Through Enamel and Dentin
The initial stage of decay occurs in the enamel, the tooth’s hard, mineralized outer layer, where it may appear as a white spot of demineralization and often causes no pain. However, once the acid erosion breaks through this tough exterior, the decay rapidly accelerates upon reaching the dentin layer beneath. Dentin is softer and less dense than enamel, making it more susceptible to acid damage.
The dentin layer is riddled with tiny channels, called dentinal tubules, which lead directly to the tooth’s central pulp chamber. When decay reaches the dentin, the primary symptom is a noticeable increase in tooth sensitivity, especially when consuming hot, cold, or sweet items. The pain at this stage is typically mild, short-lived, and intermittent, only occurring when a stimulus is applied.
Infection Reaches the Tooth Pulp
When the cavity progresses further, the bacterial infection eventually breaches the dentin and invades the pulp chamber, which contains the tooth’s living tissue, including nerves and blood vessels. This triggers pulpitis, or inflammation of the pulp tissue. Since the pulp is encased within the rigid walls of the tooth, the swelling creates immense pressure on the nerves.
The symptoms change dramatically at this point from sensitivity to intense, persistent pain. This pain is often described as a throbbing ache that can be spontaneous and may become worse at night. At this advanced stage, the pulp tissue often becomes irreversibly damaged or dies entirely (necrosis) because of the prolonged infection. The death of the nerve can sometimes cause the pain to temporarily subside, but the infection remains and continues to spread.
Abscess Formation and Systemic Risks
Once the infection has killed the pulp, the bacteria travel down the root canals and exit through the tip of the tooth root, spreading into the surrounding jawbone and soft tissues. The body’s immune system attempts to contain the infection, resulting in the formation of a dental abscess—a localized pocket of pus. Symptoms of an abscess include swelling in the face or jaw, fever, a persistent bad taste in the mouth, and sometimes swollen lymph nodes.
Ignoring this abscess allows the infection to breach the confines of the jawbone, posing a risk of systemic complications. The infection can spread locally into the soft tissues of the face and neck (cellulitis), which may lead to serious issues like Ludwig’s angina, a rapidly spreading infection that can compromise the airway. In severe cases, the bacteria can enter the bloodstream, leading to sepsis, a life-threatening systemic response that can result in organ failure. Infections from the tooth can also ascend, potentially affecting the sinuses or leading to a brain abscess.
Intervention Methods for Advanced Decay
Treatment is determined by the stage of decay, escalating in invasiveness as the condition progresses. For early decay confined to the enamel and outer dentin, a simple filling is sufficient to remove the infected material and restore the tooth structure. Once the infection has reached the pulp but the surrounding bone is not yet severely damaged, the preferred intervention is root canal therapy.
Root canal therapy involves removing the infected pulp tissue, cleaning and disinfecting the inner chamber, and then filling and sealing the canals to prevent reinfection. This procedure preserves the natural tooth structure. However, if the tooth structure is too compromised or the infection has caused extensive destruction to the surrounding bone, the tooth may be deemed unsalvageable. In such circumstances, tooth extraction becomes necessary to eliminate the source of the infection, often requiring a subsequent plan for replacing the lost tooth.