The skull is a very important bone in our head, it is the barrier between our brain and the outside world and protects the normal operation of the tissues in the brain. The skull may be defective for many reasons, such as accidental fall from a height, being hit by a heavy object that can easily cause brain damage, or the need for debridement surgery due to the lesion of the skull itself, thus causing the defect of the skull. So is there any side effect of not repairing the skull defect? Generally speaking, if the defect area is more than 3cmX3cm, skull repair is necessary. If you do not go to the hospital for repair in time, there will be a great danger that the brain tissue will not be well protected, thus affecting the normal operation of the human body, and long-term will cause patients to have a great psychological barrier, because the collapse or expansion of the brain feels different from ordinary people, resulting in a sense of inferiority and lack of self-confidence, thus greatly affecting the life and work of patients. Therefore, patients with large skull defects should undergo skull repair surgery as soon as possible within three months after surgery. Some repair materials can also cause side effects after the repair. The most widely used titanium mesh can cause rejection or other side effects in some patients after using it, so patients should also choose the repair hospital and materials carefully. Currently, some hospitals are using a new type of material for patients to perform cranial repair, polyether ether ketone material, commonly known as peek material is the most ideal repair material recognized by many experts at present.