Lecture Description
The patient was found to have a Micrognathism (mandibular retraction disorder) and was suspected to have progressive mandibular resorption (PCR), in which the mandibular head is resorbed and no joint exists. In this report, we describe two cases of patients with PCR who underwent orthognathic treatment using a combination of anterior mandibular advancement and genioplasty.
Case 1: 16-year-old female. Her chief complaint was maxillary prognathism and inability to bite with her front teeth. She had a severe mandibular retraction with ANB 13.0¡Æ, FMA 45.7¡Æ, and Pog to MacNamara -25.5.
Case 2: 20-year-old man at the initial examination. His chief complaint was that he could not close his lips. 9.8¡Æ ANB, 39.4¡Æ FMA, -13.5 Pog to MacNamara, and a severe mandibular retraction.
Treatment results
After preoperative orthodontic correction, Le Fort type I osteotomy was performed on the maxilla, and mandibular branch sagittal segmentation and genio-plasty were performed on the mandible. To flatten the advanced occlusal plane of the mandible, the surgical plan included maxillary decompression and counter-clockwise rotation of the mandible. Postoperative orthodontic treatment was performed to obtain a normal occlusion and improve their profile. Both cases have maintained a relatively stable occlusion for more than 2 years after surgery.
Discussion and Conclusion
In both cases, the patients had protruding anterior teeth, open bite, and severe plexus. Despite these conditions, the patient was able to eat as well as a normal person despite some inconvenience, suggesting that the mandibular head is not an essential organ for masticatory movement. PCR is classified as an intractable disease in Japan, but instead of diagnosing mandibular head resorption itself as a disease, we should focus on masticatory dysfunction caused by this disease or its cause.
There is no conflict of interest conditions to disclose related to the abstracts presented.
October 28-30, 2022 ¡¤ COEX, Seoul, Korea