A dental filling repairs a tooth damaged by early decay, or a cavity. This damage starts when bacteria produce acids that erode the tooth’s outer layer, the enamel. If detected early, a dentist removes the decayed material and seals the tooth with a filling to prevent further deterioration. Failing to get this treatment allows the bacterial infection to progress deeper into the tooth structure. This delay makes the problem more complex, painful, and significantly more expensive to resolve.
The Decay Deepens: From Enamel to Dentin
Delaying a filling allows decay to penetrate the enamel and reach the dentin layer underneath. Dentin is softer and more porous than enamel, allowing the infection to spread much faster. This layer is composed of microscopic channels called dentinal tubules, which lead directly to the tooth’s central pulp.
When acid and bacteria reach these tubules, the tooth exhibits noticeable sensitivity. Patients experience a sharp response to stimuli like cold, hot, or sugary sweets. This sensitivity signals that the enamel barrier has been breached and the decay is advancing rapidly toward the tooth’s nerve center.
At this stage, the damage may be too extensive for a simple filling to provide adequate structural support. The dentist may instead recommend a larger, custom-made restoration, such as an inlay or an onlay. These procedures are more involved than a standard filling, often requiring two appointments and laboratory fabrication to restore the compromised tooth structure. If the tooth’s chewing surface is significantly weakened, a full dental crown may be necessary to cap and protect the remaining portion.
Infection Reaches the Tooth’s Core
If treatment is delayed further, the infection will breach the dentin and reach the pulp chamber, the soft core of the tooth. This chamber contains the blood vessels, connective tissue, and nerves. The resulting inflammation is known as pulpitis. Because the pulp is enclosed within the rigid walls of the tooth, swelling causes immense pressure on the nerves.
When the pulp becomes infected, the pain transforms from fleeting sensitivity into a severe, constant, and throbbing ache. This discomfort is often intense enough to interrupt sleep and may be exacerbated when lying down or chewing. At this point, a filling is no longer a viable treatment option because the living tissue inside the tooth is compromised.
To save the tooth, the standard procedure becomes a root canal, or endodontic therapy. This involves drilling into the tooth, removing the infected pulp tissue, cleaning and shaping the inner canals, and then sealing them. If the tooth structure is too weakened or fractured by the decay, extraction may become the only option, sacrificing the natural tooth entirely.
Abscess Formation and Systemic Risks
The most severe outcome of neglecting an infected tooth is the formation of a dental abscess. This occurs when the bacterial infection travels through the root canal system and exits the tip of the root, spreading into the surrounding jawbone and soft tissues. The body’s immune response leads to the accumulation of pus, which forms a painful pocket at the root apex.
An acute abscess can cause significant symptoms, including facial swelling, a fever, pain when biting, and visibly swollen lymph nodes. The pressure from the pus can cause a pimple-like bump on the gums, known as a fistula, which attempts to drain the infection. This condition constitutes a medical emergency because the infection is no longer contained within the tooth.
From the jawbone, the bacteria can spread to other areas of the head and neck, leading to dangerous conditions like cellulitis, a rapidly spreading skin infection. In rare instances, the infection can progress to Ludwig’s angina, a severe infection of the floor of the mouth, or travel through the bloodstream to cause sepsis or a brain abscess. Treating these systemic infections requires immediate hospitalization, intravenous antibiotics, and often emergency surgical drainage.