Some people refuse to extract the teeth that should be extracted out of fear, while others feel that a bad tooth in the mouth is not a big deal. The residual roots and crowns that cannot be retained, if not extracted, can lead to oral odor and bad breath in mild cases; in more cases, it can lead to recurrent inflammation of the oral teeth; in serious cases, it can cause serious complications such as cellulitis, jaw bone osteomyelitis and even sepsis. Some overly sharp residual roots and crowns may pierce the gum mucosa and tongue mucosa to form ulcers, and long-term adverse stimulation may even lead to cancer, which is more common in middle-aged and elderly people, so they should be more alert. The teeth that should be extracted are not extracted, which can also cause disorder of the occlusal relationship and elongation of the teeth in the opposite jaw. In short, not extracting the teeth that should be extracted can seriously endanger health. Therefore, it is recommended that the residual roots and crowns should be extracted in time if they cannot be preserved and repaired.