The retraction osteogenesis technique of the jaws was developed based on the technique of traction lengthening of long limb bones. 1973 Synder reported the first experimental study of successful lengthening of the canine mandible using the traction lengthening osteogenesis technique, and in 1992 McCarthy successfully corrected hemifacial shortening in four children using an extraoral approach retraction device, starting the clinical application of this technique to lengthen the The clinical application of this technique to lengthen the jaw bone. I. Basic principle: Continuous traction on living biological tissues can generate tension, and this tension can stimulate and maintain the regeneration and growth of certain tissue structures, which Ilizarov called the law of tension. In the case of bone tissue, traction lengthens osteogenesis in the sense that under the action of traction, a continuous slow action is generated between segments of bone that have been cut away from the bone cortex, and this action induces the regeneration of bone tissue and periosteal soft tissue, which results in the formation of new bone and leads to the simultaneous growth of periosteal soft tissue in the gap between the drawn bone segments. This principle can be used clinically to correct not only the skeletal deformity but also the accompanying soft tissue deformity, and this change in the soft tissue is conducive to reducing recurrence and improving the orthopedic effect of various deformities. Second, the indications: almost include limb bone defects, bone resection, developmental deformities, trauma and other types of bone diseases, but also can be used to increase the height and other procedures. In the oral and maxillofacial area, this technique is mainly applied to various facial skeletal underdevelopment deformities caused by different reasons, commonly including micromaxillary deformity, maxillary dysplasia, mandibular shortening, deviated jaw deformity, hemifacial shortening, etc. Extenders: Extenders include extra-oral extenders and intra-oral extenders. The extra-oral lengtheners rely on four fixed pins through the skin to fix the lengtheners on the jawbone, during the traction lengthening process, due to the movement of the lengthener fixed pins and exposed in the conspicuous place of the cheek outside the mouth, it is inevitable to form obvious skin scar, affecting the aesthetics. The intraoral lengthener avoids this shortcoming and can lengthen the jaw bone in both horizontal and vertical directions. Application prospects: With the further maturation and development of jaw bone distraction technology, as well as the emergence of new materials and technologies, the application of the lengthener in craniomaxillofacial surgery will become increasingly widespread, and more and more conventional surgery may be partially replaced by it. This is determined by the advantages of this technology itself, on the one hand, making the operation greatly simplified, on the other hand, in some complex cases requiring extensive movement of the jaw bone correction can achieve the effect of conventional surgery can not be achieved, while the advantages of accompanying soft tissue lengthening is more conventional surgery does not have. At the same time more compact and fine, solid and stable and three-dimensional directional traction, as well as the clinical use of absorbable, automatic traction and personalized lengtheners that will emerge, will make this technology have a broader application prospect.