Final answer:
The most common dental disease affecting both children and adults is tooth decay (caries), which results from bacterial activity in the mouth leading to enamel degradation and cavity formation.
Step-by-step explanation:
The most common dental disease affecting both children and adults is tooth decay (caries). Dental caries are caused by an overgrowth of oral bacteria such as Streptococcus and Actinomyces species, that result from insufficient dental hygiene. When these bacteria feed on sugars in the mouth, they release acids that lead to inflammation and degradation of the enamel's calcium crystals. Cavities can penetrate the enamel and affect the underlying dentin and pulp, potentially leading to more severe infections such as abscesses.
Prevention of tooth decay includes maintaining proper oral hygiene, such as regular brushing and flossing, to reduce the presence of harmful bacteria. Other oral diseases such as gingivitis and periodontitis also result from microbial infections and inflammation but can be managed with good oral care and, in severe cases, the use of antibiotics.