It is a common clinical phenomenon that the upper wisdom teeth are better to be extracted than the lower wisdom teeth, mainly for the following two reasons: 1. The upper wisdom teeth have more root development and fusion, while the lower wisdom teeth tend to form thicker bifurcated roots in the process of root development. The bifurcated roots will be subjected to great resistance when extracting the teeth, and the alveolar bone will wrap the scattered roots, so it may be necessary to split the teeth and extract them by roots during the extraction process; while the wisdom teeth above are generally fused roots, which can be extracted with dental braces. The wisdom tooth below is located at the angle of the jaw, at the position of the inflection of the jawbone, where the alveolar bone is thicker and harder, so the resistance to tooth extraction is also greater.