Wisdom teeth in the following cases are more difficult to extract: 1. Longer roots and a larger number of roots can cause greater resistance to the alveolar bone, especially wisdom teeth with a large root bifurcation span, which need to be divided into roots before the resistance can be lifted and extracted separately. 2. Repeated infections produce adhesions between the wisdom tooth and the surrounding alveolar bone, which makes it difficult to enter the deeper part of the root when extracting because there is no obvious periodontal space, making it difficult to extract the tooth. 3, 4. Wisdom teeth close to the maxillary sinus may cause perforation of the maxillary sinus when extracted, and when close to the inferior alveolar nerve canal, the nerve may be damaged during surgery causing facial numbness.