Cavities refer to the chronic, progressive destructive disease of the hard tissues of the teeth under the influence of plaque bacteria. For early-stage carious white spots, fluorides, fluoride toothpaste, or topical fluoride application can be used to halt the progression of cavities at that stage and prevent further development. Inactive caries can be effectively prevented and treated by brushing and rinsing. If not taken seriously, the cavity will continue to develop deeper, which can be classified into superficial, moderate, and deep caries. After the occurrence of cavities, patients may experience pain from thermal stimuli and pain from food impaction. When the stimuli are removed, the pain disappears. Cavities need treatment. If left untreated, they can lead to pulpitis, periapical periodontitis, and even result in tooth loss. Thus, early-stage caries should be adequately attended to, with an emphasis on early detection and treatment of cavities.