Idiopathic Condylar Resorption (ICR), also known as Progressive Condylar Resorption (PCR), Condylar Specific Resorption, and Condylar Unexplained Resorption, is a type of condylar reconstruction with progressive condylar resorption and morphological changes of unknown origin. Non-functional reconstruction of the temporomandibular joint usually occurs in adolescent females and involves both sides. Idiopathic unilateral condylar resorption has also been reported. In this paper, we will review the studies related to idiopathic condylar resorption at home and abroad in recent years, and summarize the possible main causes of ICR and the ideal treatment system through the experience of clinical patients with this disease. I. Etiology of ICR Condylar resorption can be divided into adult-onset condylar resorption and adolescent-onset condylar resorption. The former is mainly manifested by the gradual regression of the mandible after the completion of growth and development, while the latter is mainly manifested by the reduction of the growth and developmental potential of the mandible. The etiology and pathogenesis of idiopathic condylar resorption are still unclear. Most scholars currently recognize that the etiology of ICR can be grouped into two main categories: host susceptibility and altered forces in the temporomandibular joint area. When the adaptability of the host is altered, or when the stress on the joint area is altered and exceeds the compensatory capacity, nonfunctional alterations occur in the temporomandibular joint, and the normal morphology and function of the joint are altered, resulting in condylar resorption. (1) Factors that influence host susceptibility include: gender, age, hormones, genetics, nutrition, and anatomy. All current studies on ICR agree that the incidence is much higher in females than in males, and our clinical statistics of the male to female ratio of ICR patients is approximately 1:10, which is consistent with this. Several studies have proven that hormones play a crucial role in the metabolic regulation of the articular disc, bone and cartilage tissues, and in the development of inflammatory responses. (2) Factors that alter the forces in the temporomandibular joint area include medically induced orthognathic surgery, intermaxillary traction, and incorrect occlusal plate treatment, all of which can cause changes in condylar position and may produce condylar resorption when condylar displacement results in excessive pressure in the joint area. Among them, Cortés et al. concluded that irreducible anterior displacement of the articular disc is significantly associated with degenerative bone changes in patients with temporomandibular joint syndrome, and that degenerative bone changes, such as flattening of the anterior bevel of the condyle, destruction of the articular surface with irregular morphology, subchondral capsule formation, bone redundancy formation, and idiopathic condylar resorption, are likely to occur after irreducible displacement of the articular disc. This is consistent with our clinical examination of patients with ICR. All patients with ICR have irreducible anterior displacement of the temporomandibular joint disc on MR examination, so the change of condylar forces due to the displacement of the joint disc may be the main cause of ICR, especially in adolescent patients during the growth period, once the joint disc is displaced, the condyle is more likely to undergo resorption and destruction. In addition, improper orthodontic traction and other treatments may aggravate the resorption, so we should pay special attention to it. There is no effective method to stop the progress of idiopathic condylar resorption. It is believed that treatment can be considered from the following aspects: removing or controlling the causative factors; maintaining the stability of the occlusion and joint; and correcting the secondary occlusal deformity. (1) Removal or control of causative factors: The presence of a systemic disease that may lead to condylar resorption should be treated or controlled when possible. Studies have shown that the use of antioxidants, tetracyclines, omega-3 fatty acids, non-steroidal anti-inflammatory drugs, and inflammatory cytokine inhibitors are effective in preventing or controlling joint disease. Based on our clinical experience all patients with ICR have a history of joint disease in adolescence (e.g., popping, limited painful mouth opening, etc.), it is important to treat TMD in adolescence promptly to prevent the possibility of ICR. (2) Keeping the stability of occlusion and joint: In order to reach the stability of restoring normal occlusion and joint function, scholars at home and abroad have adopted various methods of attempts such as: simple orthodontic and plywood treatment, orthognathic surgical treatment, mandibular distraction osteogenesis, condylar resection + rib rib cartilage graft reconstruction (CCG) treatment, prosthetic joint reconstruction + orthognathic surgery + orthodontic treatment for ICR, etc., but the stability is poor and it is very easy to have ICR recurrence, Prof. Yang Chi and Prof. Fang Bing proposed a joint-mandibular-occlusion combined treatment method in recent domestic and international joint and orthodontic conferences, using joint disc repositioning surgery + orthodontic induced bone repair and orthognathic improvement of facial shape to finally achieve ideal and stable treatment results. We also agree with this treatment system. For patients with condylar resorption and causing a series of changes in the jaw and occlusion, taking orthognathic or orthodontic treatment alone often causes relapse due to instability of the joint, especially for adolescent ICR patients. (3) Correction of secondary occlusal deformity: ICR occlusal disorder is mainly due to the reduction of ascending branch height due to condylar resorption and clockwise rotation of the mandible, resulting in an increase in the lower height, mandibular recession, and progressive opening of the anterior teeth, forming an uncoordinated facial shape of bony class II high-angle malocclusion. Correction of the secondary occlusal malocclusion must be done in a manner that prevents condylar resorption, ensures stable articular disc position, and preferably induces self-healing of the articular bone. Many adolescent ICR patients are found to have a history of orthodontic traction treatment in clinical practice, and forced orthodontic traction can lead to exacerbation of ICR, which warrants the vigilance of orthodontists and surgeons. In summary, our literature review and clinical experience concluded that TMJ disorders in adolescence, especially displacement of the articular disc, must be treated early to prevent ICR. we speculate that ICR may be an idiopathic disease in adolescence, and adult ICR is mostly a manifestation of ICR condylar resorption and stabilization in adolescence. Clinically, the possibility of ICR must be ruled out for patients with Class II high angle with anterior openings. For patients with condylar resorption and causing a series of changes in the jaws and occlusion, a combined joint-jaw-occlusion treatment approach is recommended. Orthognathic or orthodontic treatment alone often causes aggravation or recurrence of ICR due to the instability of the joint.