In clinical practice, not all cavities require X-rays, nor can all cavities be detected through X-rays. The purpose of taking X-rays is to understand the depth of the cavity and the distance between the cavity and the dental nerve. Some cavities occur on the surfaces between teeth which cannot be seen with the naked eye; in these cases, X-rays can provide a clear diagnosis. However, early-stage cavities only involve changes in the enamel, showing as chalky changes or small black dots and lines on the tooth surface. For these superficial changes, X-rays will not show any abnormalities. Therefore, it is important to maintain oral hygiene by brushing teeth morning and evening, and rinsing after meals to detect and treat cavities early, to prevent other complications.