Dental caries is the clinical term for the disease process that causes tooth decay and cavities. It is a common, diet-related condition that results in damage to the hard structures of the teeth. This process begins on a microscopic level but can advance to create visible holes or pits. The disease is not simply the presence of a cavity, but the entire sequence of events that leads to the permanent loss of tooth mineral.
The Role of Bacteria and Sugar
The oral cavity is home to millions of bacteria, but a specific group, most notably Streptococcus mutans, are the primary agents behind dental caries. These microorganisms adhere to teeth, forming a soft, sticky film known as dental plaque. This plaque consists of bacteria, their byproducts, and food debris.
These bacteria have a particular affinity for fermentable carbohydrates, especially sugars and starches. When you consume these items, the bacteria use the sugar as an energy source and produce acids, like lactic acid, as a waste product.
The more frequently a person eats sugary foods or sips sweet drinks, the more fuel is provided to these acid-producing bacteria. This repeated exposure creates a consistently acidic environment on the tooth surface within the plaque. It is this sustained acid attack that initiates tooth decay.
How a Cavity Forms on the Tooth
A tooth’s outer layer, the enamel, is the hardest substance in the human body and is composed of mineral crystals. The acids produced by plaque bacteria can dissolve these minerals, a process known as demineralization. This is when minerals like calcium and phosphate are leached from the enamel.
The mouth has a natural defense system. Saliva works to neutralize acids and redeposit lost minerals onto the tooth surface in a process called remineralization. Dental caries occurs when demineralization outpaces remineralization. Frequent sugar consumption keeps the mouth acidic, tipping this balance toward mineral loss.
The first visible evidence of mineral loss is often a “white spot lesion,” which appears as a chalky white area on the tooth. At this early stage, the decay process can be halted or even reversed. If acid attacks continue, the enamel surface will break down, creating a permanent cavity that can progress into the softer dentin layer.
Signs and Symptoms of Tooth Decay
In its earliest stages, such as a white spot lesion, dental caries may not produce any symptoms. As decay breaches the enamel and advances to the underlying dentin, the first sign is often tooth sensitivity. This manifests as a mild to sharp pain when consuming something hot, cold, or sweet.
With further progression, the signs become more apparent. The decay can appear as a brown or black stain on the tooth’s surface. A distinct pit or a visible hole may form, which can be felt with the tongue.
If decay reaches the tooth’s pulp, which contains nerves and blood vessels, symptoms become more severe. This can lead to a persistent toothache that occurs without any trigger. Pain when biting down is another common symptom of advanced decay, sometimes accompanied by swelling or pus.
Halting and Preventing the Decay Process
The most direct prevention method is consistent removal of the plaque biofilm. Brushing twice daily and flossing once a day mechanically removes bacterial colonies and food debris from tooth surfaces. This is especially important for hard-to-reach areas between teeth and near the gumline.
Modifying diet is another powerful strategy. Reducing the frequency of consuming sugary and starchy foods deprives the bacteria of the fuel they need to produce acid. When sugar is consumed less often, the mouth has more time in a neutral state, allowing saliva to remineralize the teeth.
Fluoride is a primary component of caries prevention because it supports the remineralization process. It incorporates into the enamel structure, making the crystals more resistant to acid. This is why fluoride is found in toothpaste, mouth rinses, and public water supplies, as it strengthens teeth against decay.