dental disorders
Caries
Etiology of Caries
Caries is caused by acids produced by bacteria in dental plaque. Plaque is, at first, a soft, thin film of bacteria, mucin, dead epithelial cells, and food debris that develops on the tooth surface within about 24 hours after the tooth is cleaned.Streptococcus mutansspecies are a group of related bacteria that grow in plaque and can cause caries. Some strains are more cariogenic than others. Eventually (commonly, after 72 hours), soft plaque mineralizes, mainly with calcium, phosphate, and other minerals, becoming calculus (hard plaque or tartar), which cannot easily be removed with a toothbrush. There are several risk factors for caries: Inadequate plaque control Dental defects Diet, particularly frequent consumption of dietary carbohydrates and sugars High-acid and/or low-fluoride environment Characteristics of saliva, including Xerostomia (eg, due to drugs, radiation therapy, systemic disorders that cause salivary gland dysfunction), and buffering capacity and pH Hereditary genetic factors Many teeth have open enamel pits, fissures, and grooves, which may extend from the surface to the dentin (see figure Types of cavities ). These defects may be wide enough to harbor bacteria but too narrow to clean effectively. They predispose teeth to caries. Frequent dietary exposure to carbohydrates and sugars promotes the growth of plaque-forming bacteria. Development of severe early childhood caries (rampant caries) in deciduous teeth suggests prolonged contact with infant formula, milk, or juice, typically when an infant goes to bed with a bottle (baby or nursing bottle caries). Thus, bedtime bottles should contain only water. A tooth surface is more susceptible to caries when it is poorly calcified, has low fluoride exposure, and/or is in an acidic environment. Typically, decalcification begins when the pH at the tooth falls below 5.5 (eg, when lactic acid–producing bacteria colonize the area or when people drink soft drinks, sports drinks or energy drinks, which commonly have pH values below 5.5). Older patients often take drugs that reduce salivary flow, predisposing to caries. They also have a higher incidence of root caries because of gingival recession, exposure of root surfaces, and declining manual dexterity (causing ineffective oral hygiene). Untreated caries leads to tooth destruction, infections, and the need for extractions and replacement prostheses. Premature loss of deciduous teeth may shift the adjacent teeth, hindering eruption of their permanent successors. Wong A, Subar PE, Young DA: Dental caries: An update on dental trends and therapy.Adv Pediatr64(1):307-330, 2017. doi: 10.1016/j.yapd.2017.03.011 