[Part 1: Definition & Causes of Caries – 0:20–0:50] Narration: “Dental caries is the decay of the tooth's hard tissues caused by bacteria in plaque. These bacteria really love leftover sweet food. They produce acid that slowly erodes the tooth's layers.” Footage: Sugar is consumed by bacteria → acid appears → tooth enamel begins to decay. Animated Text: “Sugar + Bacteria + Time = Caries”