Diet and oral hygiene habits play the biggest role in determining the risk of tooth decay. Some people are prone to cavities because they eat a diet high in simple carbohydrates and/or sugary beverages. Others are prone because they don’t brush and floss every day. Additionally, cavities are contagious. Once someone has one cavity in their mouth, the chances are high that a neighboring tooth will also develop decay. Some people are susceptible to decay because their teeth have been weakened by decay, wear, or acid erosion. In some rare instances, people can be born with a congenital condition that results in thin tooth enamel. For the most part, anyone can reduce their risk of dental decay by practicing good oral hygiene, limiting sweet carbohydrates, and visiting the dentist regularly.