Dental Caries

Dental caries, also called tooth decay or cavities, starts when bacteria in the mouth stick to the teeth and feed on what you eat and drink. They produce acid that begins to dissolve the outer enamel layer. Saliva clears the acid away and helps repair the enamel; if repair is not fast enough, bacteria get inside the tooth and a cavity forms. A Cochrane review describes it as an imbalance, over time, between cariogenic (decay-causing) bacteria in plaque and fermentable carbohydrates, mainly sugars. Cavities get bigger unless the bacteria are stopped or removed. Decay is very common. CDC survey data from 2017 to March 2020 show that half of US children aged 6 to 9 have had at least one cavity and 1 in 5 adults aged 20 to 64 has an untreated cavity; older CDC data (2011 to 2012) found that 96% of adults aged 65 and older had had one. As a cavity grows it causes pain and sensitivity, and one that reaches the nerve can cause an infection (abscess) that spreads. In children, cavities can interfere with eating, speaking, playing and learning. The best-proven protection is fluoride, not a supplement. A 2003 Cochrane meta-analysis of 70 trials in 42,300 children found fluoride toothpaste prevented 24% of new decayed, missing and filled surfaces compared with non-fluoride toothpaste. A separate 2019 Cochrane network meta-analysis found that in children and adolescents 1,000 to 1,250 ppm fluoride toothpaste reduced caries increments versus non-fluoride toothpaste (high- and moderate-certainty evidence), with 1,450 to 1,500 ppm slightly better; higher-concentration toothpaste also raises the risk of fluorosis in young children. CDC lists fluoride varnish, fluoridated tap water, fluoride toothpaste and dental sealants as the best-evidenced prevention. The US Preventive Services Task Force recommends fluoride varnish on the primary teeth of all infants and children under 5 once the first tooth erupts, and prescribed oral fluoride supplements from 6 months for children whose water is low in fluoride. Reviews done to inform WHO guidance found moderate-quality, mostly observational evidence that caries is lower when free sugars supply under 10% of energy. Among over-the-counter supplements and supplement-like products, the evidence is thinner. In small non-inferiority trials, fluoride-free hydroxyapatite toothpaste was not statistically worse than fluoride toothpaste, but that does not show it protects as well; xylitol, vitamin D, probiotics and arginine have low-certainty, conflicting or insufficient evidence. Trials of xylitol products reported adverse effects such as mouth sores, cramps, bloating and loose stools. None of these replaces fluoride, a low-sugar diet and regular dental care.

• •Pain and sensitivity as the cavity grows, especially near the nerve
• •Infection (abscess) if decay reaches the nerve
• •Tooth loss if cavities are not stopped
• •In children, problems with eating, speaking, playing and learning

• •Plaque bacteria that turn sugars into acid
• •Sugary or acidic food and drinks, especially between meals
• •Less saliva from medicines or health problems
• •Braces or other oral appliances
• •Exposed tooth roots
• •Difficulty brushing because of vision, cognitive or physical problems
• •Limited fluoride exposure

Plaque bacteria convert sugars into acid, and tooth enamel dissolves when acid exposure outpaces saliva's ability to neutralise and repair. Risk rises with frequent sugar or acid in food and drinks, especially between meals, with medicines or conditions that reduce saliva, with braces or other oral appliances, with exposed tooth roots, and when vision, thinking or physical problems make brushing hard. Limited fluoride exposure also raises risk: children who drink fluoridated tap water and brush with fluoride toothpaste have fewer cavities.