A root canal, or endodontic treatment, is a procedure designed to save a severely infected or damaged tooth. The process involves removing the inflamed or infected pulp—the soft tissue containing nerves and blood vessels—then cleaning, shaping, and sealing the interior of the root canal system. If a needed root canal is avoided, the bacterial infection within the tooth’s core remains unaddressed. This infection will not resolve on its own; instead, it multiplies and spreads, leading to a worsening cascade of damage.
Escalation of Local Infection
The initial consequence of an untreated deep cavity or crack is inflammation of the dental pulp, known as pulpitis. As bacteria invade the pulp chamber, the inflammation becomes irreversible because the pulp tissue is confined within rigid walls. This leads to the eventual death of the entire pulp tissue, a state called pulp necrosis.
When the nerve tissue dies, the severe pain associated with the initial infection can suddenly subside, creating a deceptive sense of relief. This silence does not indicate healing; it only means the tooth no longer has living tissue to register pain. The bacterial colony remains active within the root canal system, producing toxins and spreading deeper toward the root tip and surrounding jawbone. This transformation to a painless, chronic infection is a major step toward more destructive complications.
The Development of a Dental Abscess
Once the infection passes through the apical foramen—the small opening at the root tip—it enters the surrounding bone and soft tissues, triggering a significant immune response. This leads to the formation of a dental abscess, a localized pocket of pus. An acute periapical abscess causes severe symptoms, including facial swelling, throbbing pain, and sensitivity to heat, cold, or pressure on the tooth.
Alternatively, the body may attempt to drain the pus by forming a small channel, or fistula, that opens onto the gum line, often appearing as a pimple-like bump called a “gum boil.” This chronic abscess often causes little pain because the fistula acts as a pressure-release valve, allowing the infection to drain continuously into the mouth. While less painful, a draining fistula still signifies a severe, ongoing bacterial infection that actively destroys the underlying bone structure.
Structural Damage and Tooth Loss
The chronic presence of a periapical infection initiates a destructive process in the tooth’s supporting structures. The body’s immune response, while attempting to contain the bacteria, inadvertently signals for the breakdown of the alveolar bone that anchors the tooth. Specialized cells called osteoclasts are activated, whose function is to resorb, or dissolve, the jawbone around the infected root tip.
This progressive bone resorption weakens the tooth’s foundation, leading to a loss of structural support. Furthermore, the chronic inflammatory process destroys the periodontal ligaments, the fibers that connect the tooth root to the bone. As support diminishes, the tooth becomes loose and mobile. At this stage, the damage is often so extensive that a root canal is no longer a viable option, and the only remaining treatment is extraction. Tooth loss then necessitates more complex and costly restorative procedures, such as dental implants or bridges, to prevent further bone loss and maintain chewing function.
Spread of Infection to Other Body Systems
The most serious risk of an untreated root canal infection is the potential for bacteria to spread beyond the jawbone into the surrounding soft tissues or the bloodstream. The infection can spread rapidly through fascial spaces in the neck and face, leading to conditions like cellulitis, a life-threatening soft tissue infection. One particularly dangerous complication is Ludwig’s Angina, a severe form of cellulitis affecting the floor of the mouth, typically originating from an abscessed lower molar.
As the infection spreads, the resulting swelling can push the tongue upward and backward, quickly leading to airway obstruction and making breathing difficult. The infection can also travel downward into the chest cavity, causing descending necrotizing mediastinitis, or enter the bloodstream and spread to distant organs. These systemic infections are medical emergencies requiring immediate hospitalization, intravenous antibiotics, and potentially surgical drainage to prevent a fatal outcome.