• What is Tooth Decay?
  • How Will I Know if I Have a Cavity?
  • How Do Dentists Detect Cavities?
  • Are Some People at More Risk for Developing Cavities?
  • How Can I Prevent Cavities?
  • What should I do if I have tooth decay?

What is Tooth Decay?

Dental cavities are an infection caused by a combination of carbohydrate-containing foods and bacteria that live in our mouths. The bacteria are contained in a film that continuously forms on and around our teeth. We call this film plaque. Although there are many different types of bacteria in our mouths, only a few are associated with cavities. Some of the most common include Streptococcus mutans, Lactobacillus casei and acidophilus, and Actinomyces naeslundii.

When these bacteria find carbohydrates, they eat them and produce acid. The exposure to acid causes the pH on the tooth surface to drop. Before eating, the pH in the mouth is about 6.2 to 7.0, slightly more acidic than water. As “sugary foods” and other carbohydrates are eaten, the pH drops. At a pH of 5.2 to 5.5 or below, the acid begins to dissolve the hard enamel that forms the outer coating of our teeth.
As the cavity progresses, it invades the softer dentin directly beneath the enamel, and encroaches on the nerve and blood supply of the tooth contained within the pulp.
Cavities attack the teeth in three ways:
1. Pit & Fissure
2. Smooth surface
3. Root surface

The first is through the pits and fissures, which are grooves that are visible on the top biting surfaces of the back teeth (molars and premolars). The pits and fissures are thin areas of enamel that contain recesses that can trap food and plaque to form a cavity. The cavity starts from a small point of attack, and spreads widely to invade the underlying dentin.

Decays formed at the the pits and fissures and spread to the whole biting surface of the teeth

The second route of acid attack is from a smooth surface, which is between, or on the front or back of teeth. In a smooth-surface cavity, the acid must travel through the entire thickness of the enamel. The area of attack is generally wide, and comes to a point or converges as it enters the deeper layers of the tooth.

At the smooth surface area, decay started in-between of the teeth

The third is the attack started at the root surface of the tooth after it was exposed to the oral cavity. The root is usually exposed due gum recession as a result of periodontitis (gum disease)

Decay at the root surface of the teeth

Recipe for tooth decay formation?

How Will I Know if I Have a Cavity?

The large majority of cavities are completely painless. This is because the outer enamel has no nerves. It is only when the cavity enters the underlying dentin that the cavity may begin to feel sensitive (Teeth sensitive). The most common cavity symptoms are an increased sensation to cold, sweet foods or beverages. A cavity is often responsible for a broken tooth. The cavity weakens the tooth, especially when it forms under a tooth filling or a tooth cusp, and can easily cause a fracture when biting down.

Sensitive Teeth

Patients are sometimes taken off guard when they learn that they have a few cavities but they don’t have any symptoms. It is far better to treat a small cavity than to wait until they have symptoms; such as pain. By the time there are symptoms, the cavity may have spread to infect the dental pulp, necessitating a root canal procedure or a tooth extraction to eliminate the infection. Always remember that most dental problems are insidious — that is, they sneak up on you. Regular dental exams, at least twice a year, will greatly reduce the likelihood that a dental cavity will go undetected and spread, causing toothache pain and infecting the dental pulp.

The decay has spread into dental pulp causing pain

How Do Dentists Detect Cavities?

Cavities are detected a number of ways. The most common are clinical (hands-on) and radiographic (X-ray) examinations. During a clinical exam, the dentist uses a handheld instrument called an explorer to probe the tooth surface for cavities. If the explorer “catches,” it means the instrument has found a weak, acid damaged part of the tooth — a dental cavity. Dentists can also use a visual examination to detect cavities. Teeth that are discolored (usually brown or black), can sometimes indicate a dental cavity.

Regular dental examination is important to prevent tooth decay

Bite-wing radiograph is good to detect interproximal (in-between) caries

Dental X-rays, especially check-up or bitewing X-rays, are very useful in finding cavities that are wedged between teeth, or under the gum line. These “hidden” cavities are difficult or impossible to detect visually or with the explorer. In some cases, none of these methods are adequate, and a dentist must use a special disclosing solution to diagnose a suspicious area on a tooth.

Are Some People at More Risk for Developing Cavities?

People who have reduced saliva flow due to diseases such a Sjogren Syndrome; dysfunction of their salivary glands; have undergone chemotherapy or radiation; and who smoke are more likely to develop cavities. Saliva is important in fighting cavities because it can rinse away plaque and food debris, and help neutralize acid. People who have limited manual dexterity and have difficulty removing plaque from their teeth may also have a higher risk of forming cavities. Some people have naturally lower oral pH, which makes them more likely to have cavities.

How Can I Prevent Cavities?

The easiest way to prevent cavities is by brushing your teeth and removing plaque at least three times a day, especially after eating and before bed. Flossing at least once a day is important to remove plaque between your teeth. You should brush with a soft-bristled toothbrush, and angle the bristles about 45 degrees toward the gum line. Brush for about the length of one song on the radio (three minutes). It’s a good idea to ask your dentist or hygienist to help you with proper brushing methods.

Blushing and Flossing teeth are to do it daily to stop caries

Reducing the amount and frequency of eating sugary foods can reduce the risk of forming cavities. If you are going to drink a can of sweetened soda, for instance, it is better to drink it in one sitting, than sip it throughout the day. Better yet, drink it through a straw in one sitting, to bypass the teeth altogether. Getting to the dentist at least twice a year is critical for examinations and professional dental cleanings.

Reduce high sugar food can reduce dental cavity significantly
To reduce the incidence of cavities, use toothpaste and mouthwash that contains fluoride. Fluoride is a compound that is added to most tap water supplies, toothpastes, and mouth rinses to reduce cavities. Fluoride becomes incorporated into our teeth as they develop and makes them more resistant to decay. After our teeth are formed, fluoride can reverse the progress of early cavities, and sometimes prevent the need for corrective dental treatments.

Mouthwash with fluoride

The recent drop in the number of cavities is largely due to the addition of fluoride to our drinking water. Mass water fluoridation is the most cost-effective measure available to reduce the incidence of tooth decay. The Environmental Protection Agency has determined that the acceptable tap water concentration for fluoride is 0.7 to 1.2 parts per million.

A dental procedure called sealants can also help reduce cavities on the top and sides of back teeth (occlusal, buccal and lingual surfaces). A sealant is a white resin material that blankets the tooth, protecting the vulnerable pits and fissures of the tooth. Sealants are routinely placed on children’s teeth to prevent cavities on their newly developing molars. The use of sealants to prevent cavities is also a cost-effective way to reduce the incidence of cavities on adults as well. Sealants are generally not used on teeth that already have fillings.

Fissure Sealant

People who have a dry mouth are at risk for developing cavities, and can have their dentist prescribe artificial saliva and mouth moisturizers, as well as recommend chewing sugarless gum to stimulate saliva production. Finally, an antiseptic mouthwash containing chlorhexidine gluconate such as Chlohexxa or Oradex can also be useful in killing bacteria associated with dental caries.

What should I do if I have tooth decay?

You should go the to dental clinic as soon as possible. Early or small decay is easily to treat. Usually a small filling will do. However if it is large cavity, then a larger filling is required provided there is no pain. In cases where the tooth is painful (eg. pain on biting, disturb sleep), then root canal treatment or extraction is required to stop the infection.
Small filling
Filling can be silver (amalgam) or white (composite).
Large Filling
Usually required
Comparison within big and small filling:
Small Filling                           vs.       Large filling

  • Less pain during filling                More pain (because lager & deeper cavity)
  • More aesthetic                             Less aesthetic
  • More lasting and durable             Less durable
  • Cheaper                                       More expensive (more filling material)

Or tooth capping of is a procedure to created back function, aesthetic as well as protection to a severely damaged tooth. It is usually made of porcelain fused with metal or a full porcelain material. Crown is durable and more lasting compared to a large filling.


Root canal treatment (RCT)
RCT is required when infection from caries has spread to the pulp of a tooth. The tooth is usually painful on chewing and sometimes disturb sleep. The purpose of this treatment  is to preserve the tooth by removing the dead and infected pulp leaving the tooth bacteria free.
After RCT, the tooth can be restored with filling or a corwn. If there is a lot of tooth structure loss, the tooth should be protected with a crown.

Root Canal Treatment

Tooth extraction in another way to stop infection. However, this method is commenced  if patient don’t want to keep the tooth anymore. Patient have to understand the consequent of removing the tooth
Root canal treatment              vs.        Tooth extraction

  • Tooth preserved                             Tooth removed
  • Difficult (esp molar tooth)              Simple & fast
  • Expensive                                       Cheaper than RCT
  • Few visits                                       One visit
  • Lesser problems in future              More problems in future

Tooth Extraction

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