A “dead tooth,” or dental pulp necrosis, occurs when the soft tissue containing nerves and blood vessels inside the tooth chamber dies. This condition is typically the result of deep decay, trauma, or a crack that allows bacteria to invade the pulp. An unpleasant smell or taste is a strong indicator that the internal tissue has died and become infected, as this foul odor is a byproduct of biological processes occurring within the tooth.
Why Necrotic Teeth Develop an Odor
The foul smell associated with a necrotic tooth stems from the metabolic activity of bacteria that thrive in the absence of oxygen. When the blood supply to the pulp is severed, the internal chamber becomes an anaerobic environment, which is ideal for specific types of microorganisms. These anaerobic bacteria, such as Porphyromonas and Treponema species, feed on the dead pulp tissue, which is composed of proteins.
The bacteria break down sulfur-containing amino acids within the necrotic tissue, a process called putrefaction. This metabolic breakdown generates gaseous waste products known as Volatile Sulfur Compounds (VSCs). The primary VSCs responsible for the offensive smell are hydrogen sulfide (rotten-egg odor) and methyl mercaptan (foul or skunky smell).
These gases accumulate within the sealed pulp chamber and surrounding infection, such as an abscess. When the infection drains or gas pressure builds up, foul-smelling and foul-tasting fluid or gas can be released into the mouth. This localized, persistent bad taste and smell is often the first unmistakable sign of the deep infection.
Other Signs of a Non-Vital Tooth
Beyond the unpleasant odor, a necrotic tooth often exhibits a noticeable change in color. As the pulp tissue breaks down, byproducts from blood and tissue disintegration, including iron sulfides, leach into the porous dentin structure. This internal staining causes the tooth to appear darker than its neighbors, often presenting as a gray, brown, or sometimes black hue.
The discoloration tends to become more pronounced the longer the necrosis goes untreated. A non-vital tooth may also lose its characteristic translucency, appearing dull or opaque.
While pain can be a primary symptom, a necrotic tooth may sometimes be completely asymptomatic, or the pain may have subsided after the initial pulp death. When an infection spreads beyond the root tip, it can cause severe, throbbing pain that may radiate to the jaw, ear, or neck. Tenderness or discomfort when biting, chewing, or tapping the tooth is common due to inflammation in the supporting ligaments. Swelling of the gum tissue near the root tip, sometimes appearing as a pimple-like bump that may drain pus, is a sign of an abscess forming beneath the tooth.
Necessary Dental Treatment Options
Addressing a necrotic tooth eliminates the source of the infection and prevents its spread. The infection will not resolve on its own, and delaying treatment allows bacteria to travel from the tooth root into the surrounding jawbone and potentially other areas of the body.
The standard procedure for saving a tooth with pulp necrosis is Root Canal Therapy (RCT). This treatment involves accessing the pulp chamber, removing the infected tissue, and thoroughly cleaning and disinfecting the entire root canal system. The cleaned space is then filled with a biocompatible material and sealed to prevent future bacterial re-entry.
If the tooth is extensively damaged, severely fractured, or the infection is too widespread, extraction may be the only option. Removing the tooth eliminates the source of the infection and is followed by cleaning the socket to ensure all infected tissue is gone. A missing tooth requires replacement, such as a dental implant or bridge, to maintain proper bite function and prevent adjacent teeth from shifting.