The 5 Stages of Tooth Decay

November 08, 2015

The 5 Stages of Tooth Decay
Initial tooth lesions look like white or brown spots on the teeth and are caused by demineralized enamel.
Enamel decay, also known as a superficial cavity, is an infected enamel structure on the teeth surface.
When the caries progresses into dentin we have a deep cavity, also known as dentin decay.
When the tooth cavity reaches the pulp, the last becomes infected. This is the stage of pulpal decay.
The infection is spread through the pulp into the periodontal and bone tissues forming a tooth abscess.
Tooth decay
Tooth decay, dental cavity - a microscope view
This is how dental decay (tooth caries) looks

Decay happens when acids in your mouth attack the hard outer layer of your teeth (enamel) through a process called demineralization. It starts small, undetectable to the naked eye. Then it progresses, traveling through the protective layers of the tooth. Eventually it reaches the inner chamber where infection can cause serious damage. Don’t let decay get this far. Instead watch for stages of decay and prevent damage early. Then, if you think you have a cavity, talk to your dentist right away.


The Demineralization Process

The enamel of your teeth is made of a crystalline structure of minerals - primarily calcium, but also phosphorous and magnesium. It is the hardest substance in the human body, but it is not impervious. It can break down and lead to cavities, infection, and even the loss of a tooth. The degradation of minerals, or decay, stems from bacterial activity on the surface of the enamel. There is a clear sticky substance on teeth called plaque. It is a mixture of saliva, bacteria, and food particles left on teeth after each meal. The bacteria trapped in the sticky film feed on the sugars and starches, and produce an acid by product. These acids have the ability to degrade the strong structure of the enamel. The process starts with reducing the mineral content in the enamel and weakening of the outer layer. Eventually a hole (cavity) forms in the protective layer and infection can rapidly spread. This is why it is so important to know and recognize that initial stage of decay, and what you can do to prevent the problem from getting worse.


What are the Stages of Tooth Decay?

There are five key stages of dental decay, characterized by the symptoms exhibited. They include:


Stage 1: Initial Lesion

This is the earliest form of a cavity often categorized by a white or brown spot lesion on the surface of the enamel. This dull spot is where demineralization has taken place at a microscopic level. The tooth is still hard to the touch and the cavity is not yet visible on dental x-rays. Routine dental exams every six months are designed to catch this exact stage of decay. Then the dentist can take proactive steps towards remineralizing the surface of teeth and preventing decay from progressing any further. At this stage patients can repair the damage by limiting sugary foods, brushing with fluoride tooth paste after every meal, and flossing at least once a day. The dentist might also recommend fluoride therapy and protective sealants as preventative measures.


Stage 2: Enamel Decay

If steps are not taken to reverse or protect the initial lesion, acids from bacteria continue to break down the structure. They continue on until they reach the inner layer of teeth called dentin. The decay is now a cavity in the enamel and visible on x-rays. With no enamel to protect it, the dentin is exposed. Because the dentin directly links to the nervous center of the tooth (pulp), teeth at this stage of decay often become sensitive to hot, cold, sour, and sweet. However, many patients do not experience symptoms until very late. Once a cavity forms, the dentist cannot reverse the damage with remineralization. Instead, the infected and decayed tissue should be mechanically drilled away and replaced with a filling.


Stage 3: Dentin Decay

Decay now progresses beyond the enamel and starts to infect the dentin. This layer of your tooth, though still made of minerals, is far more porous. This means decay progresses more quickly. The hole in the tooth gets bigger, faster. Levels of discomfort and sensitivity will intensify. The dentist can still use a filling to repair the damage, or larger cavities may require inlays or onlays, a more extensive restoration.


Stage 4: Pulpal Decay

Once decay works through the dentin it continues deeper into the tooth until it reaches the soft tissue, the pulp. This portion of the tooth is the nerve chamber and includes the blood vessels and nerves of the tooth. Because of bacteria, the pulp gets infected, pus begins to form, and the nerves and tissue begin to break down and die. This is a serious condition, and the only treatment option is root canal therapy. The dentist must go in, remove all the decayed pulp and clean out the innards all the way down into the root canals of the tooth. Then the dentist disinfects the inside of the tooth, fills it, and seals it off.


Stage 5: Formation of an Abscess

If patients do not take action at pulpal decay, the infection travels deeper into the tooth, all the way to the root tip. From there infection can spread to the bones and other supporting structures of teeth. So not only does the infected tooth die, but surrounding teeth could be at risk as well. Patients often experience severe pain, swelling, and inflammation along the infected side. Patients should deal with an abscessed tooth immediately. Otherwise infection can rapidly spread to the rest of the body and cause serious systematic problems. The dentist will perform a root canal or complete extraction depending on the severity of infection.


Cavities do not crop up overnight. Instead it takes days, weeks, and months of repeated exposure to sugars and acids to fully break down the enamel and lead to infection or decay. And fortunately there are several things patients can do to stall the progress of decay. Prevention starts with proper oral hygiene at home. It also includes regular visits to your dentist every six months for routine exams and professional dental prophylaxis. Then, if a patient notices a symptom linked to the stages of decay, he or she should seek treatment early, to stop the problem before it progresses into something more serious.


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