Since the last tooth is a wisdom tooth, most of them have obstruction, so before the wisdom tooth is extracted, an X-ray is taken to understand the morphology and location of the obstructed wisdom tooth, its relationship with the surrounding bone tissue and neurovascular. The cost of the x-ray is about RMB 100; for maxillary wisdom tooth extraction, the cost is about RMB 230. If it is the extraction of mandibular wisdom teeth without obstruction, the cost is about 300 RMB; if it is the extraction of mandibular obstructed wisdom teeth, the extraction process requires incision and flap of mucosa, removal of bone resistance and removal of resistance of neighboring teeth, the extraction is difficult and the cost will be relatively higher, ranging from about 500-1000 RMB.