There are several Ken’s categories of tooth loss, depending on the tooth loss and the location of the loss. If bilateral posterior teeth are missing at the free end, it is called Ken’s Class I. If unilateral posterior teeth are missing at the free end, it is called Ken’s Class II. If a unilateral posterior tooth is missing at the free end, it is called Ken’s Class II. If there are abutment teeth in front and behind, the missing teeth in between are called Ken’s Class III. If the missing tooth is located in the anterior part of the dentition and crosses the midline, with both anterior and posterior abutment teeth in the distal center, it is called Ken’s Class IV. In addition to Ken’s Class IV, other types of teeth are divided into dental classes, according to the number of missing tooth parts, there are dental class I and dental class II, mainly for later restoration of dental defects, for more accurate design and naming, and more refined.