What are the side effects of not replacing a skull defect? It is important to know that the skull is a very important bone in our head, which 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, due to accidentally being hit by something that can easily cause brain damage, or due to the lesion of the skull itself that requires debridement surgery, thus causing the defect of the skull. Are there any side effects of not repairing a 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 great harm, not to make the brain tissue get a good protection, thus affecting the normal operation of the human body, and long-term will make patients have great psychological barriers, because the collapse or expansion of the brain feel different from ordinary people, resulting in low self-esteem, not confident, 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. At present, some hospitals are using a new 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, in use since, many patients with cranial repair have undergone repair surgery through peek material, and after long-term follow-up found that the basic recovery after surgery is very good.