Tooth decay, also called cavities or dental caries, is the most prevalent chronic disease in both children and adults worldwide. Tooth decay occur as a result of an infection with certain types of bacteria that use sugars in food to make acids that attack the teeth. Over time, these acids destroy tooth enamel, making a cavity in the teeth that may progress gradually in tooth layers, causing complaint and losing the tooth at the end.

Tooth decay may not be noticed until going deeply through the tooth, then it will trigger pain or simply can be visible as a hole or a pit in the affected tooth. The dentist can detect the degree of tooth decay and determine the best treatment for it. Such of these can include fillings, root canals, crowning, and tooth extraction as a last choice.

Tooth decay is much easier and cheaper to treat in its early stages. If neglected, the situation can worsen to severe conditions that interfere negatively with person’s wellbeing. The person may complain of severe toothache, the gum may inflame and bleed, and the teeth may eventually be lost.

Oral health is essential to general health and quality of life. The person can protect his/her teeth by controlling factors that lead to tooth decay. Brushing twice daily and limiting sweetened foods and beverages are among the strongest approaches for tooth decay prevention. Regular visits to the dental clinic, even without teeth symptoms, are also recommended to check for any hidden problem and/or anticipate any of which that may occur.

Tooth decay, or cavities, or dental caries is permanent destruction of the hard surface of the teeth (tooth enamel). Tooth decay can occur when acid is produced from oral bacteria, which builds up on the teeth and cause the formation of holes that may extends more deeply in the them and worse the damage. Tooth decay is very common and can be a problem for children, teens and adults.

There are three types of tooth decay or cavities:

• Smooth surface cavities. They occur on the smooth sides of the teeth where bacteria dissolve the enamel. It is the most preventable and reversible type, and grows the slowest;
• Pit and fissure cavities. A Pit and fissure cavity appears on the chewing surface of the tooth, usually the back teeth. Decay at these locations progresses rapidly;
• Root cavities. They begin on the root surface covering (cementum) that has been exposed by receding gums. Root decay can be the most difficult type of tooth decay to prevent and treat.

Tooth decay is caused by the action of acids on the enamel surface. The acid is produced when sugars in foods or drinks react with certain bacteria present in the dental biofilm (plaque) on the tooth surface. From these microorganisms Streptococcus mutans, non-mutans streptococci group, Actinomyces and Lactobacillus.

The acid produced by the bacteria can include lactic, formic, acetic and propionic acids. This will cause a decrease in pH level below 5.5, which leads to a loss of calcium and phosphate from the enamel in a process called demineralization. Over time, these acids destroy tooth enamel, making a cavity in the tooth.

Everyone who has teeth is at risk of getting cavities, but the following factors can increase that risk:

• Tooth location. Decay most often occurs in the back teeth. These teeth have lots of grooves, pits and crannies that can collect food particles, which forms a preferable medium for bacteria to thrive and form plaques;
• Certain foods and drinks. Foods that cling to the teeth for a long time - such as milk, ice cream, honey, sugar, soda, dried fruit, cookies, hard candy, dry cereal, and chips - are more likely to cause decay than foods that are easily washed away by saliva;
• Frequent snacking or sipping. Having snakes – which usually is rich in sugar and starch - give mouth bacteria more fuel to produce acids that attack the teeth and wear them down. Soda or other acidic drinks throughout the day helps create a continual acid bath over the teeth;
• Poor oral hygiene. Inadequate brushing of the teeth can lead to plaque formation and the first stages of decay can begin. However, brushing should not be right away after eating to prevent acids from going deeper. The person has to wait for nearly 30 munities before brushing;
• Not getting enough fluoride. Fluoride mineral helps prevent cavities and can even reverse the earliest stages of tooth damage. Because of its benefits for teeth, fluoride is added to many public water supplies. It's also a common ingredient in toothpaste and mouth rinses;
• Age. Cavities are common in children and teenagers. Older adults also are at higher risk. That’s may be why about 30% of people aged 65–74 have no natural teeth (World health organization);
• Dry mouth. Dry mouth is caused by a lack of saliva, which helps prevent tooth decay by washing away food and plaque from the teeth and remineralization of it. Certain medications, some medical conditions, radiation to head or neck, and certain chemotherapy drugs can cause this problem;
• Gastroesophageal reflux disease (GERD). This condition can cause stomach acid to flow into the mouth, wearing away the enamel of the teeth and causing significant tooth damage;
• Worn fillings or dental devices. Over the years, dental fillings can weaken, begin to break down or develop rough edges. This allows plaque to build up more easily and makes it harder to be removed;
• Frequent vomiting. Stomach acids from recurrent vomiting can lead to significant tooth erosion and cavities. Certain eating disorder called bulimia nervosa may associated with increased risk of tooth decay and cavities, as a result of self-induced vomiting to empty the stomach after eating;
• Bedtime infant feeding. Parents are encouraged not to give babies bedtime bottles filled with milk, formula, juice or other sugar-containing liquids. These beverages will remain on teeth for hours while the baby sleeps, providing food for decay-causing bacteria;
• Diabetes. Poor controlled blood sugar may affect oral health and increase the risk of having many oral problems, such as dry mouth, gingivitis, and lesions inside the oral cavity;
• Receding Gums. Recession of the gums away from the teeth will expose teeth roots to plaque and increase the chance of having root cavities.

The mouth contains Hundreds of different types of bacteria that live on the teeth, gum, tongue and other places inside. Some bacteria are helpful. But others can be harmful such as those that play a role in the tooth decay process. Whenever we eat or drink something that contains sugar or starch, the bacteria use them to produce acids that start eroding teeth. This take place in what is called the dental plaque - a sticky, colorless film of bacteria and food that adhere to the teeth surface.

In the other hand, Saliva acts to dilute and neutralize the acid and handle the essential elements for teeth remineralization, thus it is considered an important natural defense against caries. The enamel demineralizes and re-mineralizes many times during the course of a day. It is when this balance is upset and demineralization exceeds remineralization that caries progresses. When demineralization occurs frequently and beats remineralization over many months, there is a tiny openings or holes in the enamel.

Once areas of enamel are worn away, the bacteria and acid can reach the next layer of the teeth, called dentin. This layer is softer than enamel and less resistant to acid. As tooth decay develops, the bacteria and acid continue their march through the tooth, moving next to the inner tooth material (pulp) that contains nerves and blood vessels. The pulp becomes swollen and irritated from the bacteria. When decay advances to this extent, the person may have a severe toothache or sensitivity.

Tooth decay runs silently and may not cause any pain until develop to a more progressed condition. Depending on their extent and location of tooth cavities, the person might have:

• Toothache; either continuous, or occasional sharp pain;
• Teeth sensitivity. A feeling of tenderness when having something hot, cold or sweet;
• Grey, brown or black spots appearing on the teeth;
• Visible holes or pits in the teeth;
• Bad breath caused by food fermentation by bacteria;
• An unpleasant taste in the mouth from bacterial byproducts.

Identification of tooth decay in its early stages in not easy. However, some new invented and approved machines use safe, painless pulses of laser through the tooth structure to uncover hidden cavities. In the later stages, tooth decay can be detected with tooth pain and examination of the teeth in the dental clinic. The dentist may use an x-ray image to see the extent of cavities and decay.

Treatment of tooth decay depends on how severe they are and the particular situation of the affected person. Treatment options include:

• Fluoride treatments. If the cavity is just getting started, a fluoride treatment may help restore tooth's enamel. Professional fluoride treatments contain more fluoride than the amount found in tap water, over-the-counter toothpaste and mouth rinses. Fluoride treatments may be liquid, gel, foam or varnish that's brushed onto the teeth or placed in a small tray that fits over them. Each treatment takes a few minutes;
• Fillings. Sometimes called restorations, Fillings are the main treatment option when decay has progressed beyond the earliest enamel-erosion stage. Fillings are made of various materials, such as silver amalgam and tooth-colored composite resins. The last are a good choice for people who prefer that their fillings look more natural;
• Root canals. These are needed when decay reaches the inner material of the tooth (pulp). In a root canal treatment, the dentist removes the diseased tooth pulp to repair and save a badly damaged or infected tooth. Medication is sometimes put into the root canal to clear any infection. Then the pulp is replaced with a filling;
• Crowns. If the person has extensive decay or weakened teeth, he may need a crown - a custom-fitted covering that replaces your tooth's entire natural crown. The dentist will drill away all the decayed area and enough of the rest of the tooth to ensure a good fit. Crowns may be made of gold, porcelain, resin, or other materials;
• Tooth extractions. Some teeth become so severely decayed that they can't be restored and must be removed. Having a tooth pulled can leave a gap that allows the other teeth to shift. If possible, the person has to consider getting a bridge or a dental implant to replace the missing tooth;
• Antibacterial therapy. People who are very prone to recurrent tooth decay may need antibacterial therapy. Dentists first removes cavities and seal all pits and fissures in the teeth. Then dentists prescribe a powerful mouth rinse (chlorhexidine) that is used for 2 weeks to kill off the bacteria in any remaining plaque. To keep bacteria under control, people may chew gum or suck a hard candy containing xylitol (a sweetener that inhibits the bacteria in plaque).

Cavities and tooth decay are so common that we may not take them seriously. However, if the person didn’t take care about mouth health, the decay can progress into serious conditions, such as:

• Severe Pain. If the decay reached the tooth bulb, it may cause intolerable pain that usually is described as the worst pain ever. Severe Toothache can interfere with daily living, preventing from going to school or work. It can also cause Weight loss or nutrition problems from painful eating or chewing;
• Gum disease (gingivitis). Gum disease is an inflammation of the gum tissue the surround the teeth caused by a build-up of plaque on them. The result is red, swollen, or even bleeding gum that will cause pain and discomfort;
• Periodontitis. If gum disease is not treated, it can develop into a more severe form called Periodontitis. Beside the gum, the inflammation also affects the tissue that connects the tooth to the tooth socket, and may reach to the jaw bone. The teeth will be lost at the end;
• Dental abscesses. In some cases of advanced tooth decay, bacteria can cause a pus-filled swelling to develop in the mouth. This is known as a dental abscess that can cause severe pain, or other symptoms of infection, such as fever.

Even almost all have some kind of tooth decay, dental cavities are considered preventable. Healthy habits and regular follow-ups may help protect the teeth and prevent suffering later. Every person is advised to:

• Brush the teeth at least twice a day with a fluoride-containing toothpaste. Preferably, brushing after half an hour of each meal and especially before going to bed;
• Clean between the teeth daily with dental floss or interdental brush. This will allow to remove foods suspended between teeth;
• Rinse daily with a fluoride-containing mouthwash. Some rinses also have antiseptic ingredients to help kill bacteria. However, a mouth wash should not be used more than three times a day, as it may increase oral cancer risk;
• Eat tooth-healthy foods. Some foods and beverages are better for teeth than others. Fresh fruits and vegetables increase saliva flow, and unsweetened coffee, tea and sugar-free gum help wash away food particles;
• Cut down on sugary and starchy food and drinks, particularly between meals or within an hour of going to bed. Sticky carbohydrates such as candy, pretzels and chips, should be avoided as much as possible;
• Drink some tap water. Most public water supplies have added fluoride, which can prevent tooth decay from progressing. It can even reverse, or stop, early tooth decay. That had carried CDC to name community water fluoridation one of 10 great public health achievements of the 20th century;
• Avoid smoking or drinking alcohol excessively. Tobacco can interfere with saliva production that helps to keep the teeth clean. It also alters the composition of the oral microbiome to increase percentage of bacteria that cause tooth decay. Alcohol can contribute to the erosion of tooth enamel;
• Ask the dentist about dental sealants; a plastic protective coating applied to the chewing surfaces of the back teeth (molars) to protect them from decay;
• Regular dental checkups. The person may not be aware that a cavity is forming. For that it is formerly advised to see the dentist at least every 6 months. The time between check-ups can vary based on the situation.

Tooth decay progress with time depending on the oral health condition and personal lifestyle. Over time, the enamel is weakened and destroyed, forming a cavity. A cavity is permanent damage that need to be treated. Although a cavity may take 2 or 3 years to penetrate the enamel, it can travel from the dentin to the pulp in as little as a year. Thus, root decay that starts in the dentin can destroy a lot of tooth structure in a short time. If the problem isn't treated early, it can develop into more serious complications and the tooth will be lost eventually after a huge suffering from pain and other undesirable symptoms of deferent oral health problems caused by tooth decay.

Diseases of the mouth, such as tooth decay are among the most common no communicable diseases in the world and, traditionally, some of the most neglected. According to World health organization (WHO), 60–90% of school children and nearly 100% of adults Worldwide have dental cavities, often leading to pain and discomfort. A recent Global Burden of Disease study, has showed that untreated tooth decay is the most prevalent of 291 major diseases and injuries.

The incidence of tooth decay in low- and middle-income countries is rapidly increasing among adults and children and there will be a huge burden of this health problem in the future without sustainable prevention programs. The relation between Sugar and tooth decay has been clearly identified. The horrible increase in the rates of sugar consumption are blamed to the phenomenon of food decay and cavities in both, developed and developing countries, especially in young children.