Cone-beam computed tomography-based diagnosis and treatment simulation for a patient with a protrusive profile and a gummy smile / 대한치과교정학회지

For patients with bimaxillary protrusion, significant retraction and intrusion of the anterior teeth are sometimes essential to improve the facial profile. However, severe root resorption of the maxillary incisors occasionally occurs after treatment because of various factors. For instance, it has been reported that approximation or invasion of the incisive canal by the anterior tooth roots during retraction may cause apical root damage. Thus, determination of the position of the maxillary incisors is key for orthodontic diagnosis and treatment planning in such cases. Cone-beam computed tomography (CBCT) may be useful for simulating the post-treatment position of the maxillary incisors and surrounding structures in order to ensure safe teeth movement. Here, we present a case of Class II malocclusion with bimaxillary protrusion, wherein apical root damage due to treatment was minimized by pretreatment evaluation of the anatomical structures and simulation of the maxillary central incisor movement using CBCT. Considerable retraction and intrusion of the maxillary incisors, which resulted in a significant improvement in the facial profile and smile, were achieved without severe root resorption. Our findings suggest that CBCT-based diagnosis and treatment simulation may facilitate safe and dynamic orthodontic tooth movement, particularly in patients requiring maximum anterior tooth retraction.

The application of digital simulation positioning machine in radiation therapy oncology / 实用医学杂志

Objective To discuss the application of digital simulation positioning machine in radiation oncology. Methods We used digital simulation positioning machine to shoot isocenter reset digital simulator images of 0 degrees direction and 90 degrees direction, 10 × 10 cm2 rectangular field and actual time radiation field with any field number. Compared the images taken with the TPS corresponding DRR image through bone marker matching to measure the error of isocenter and actual time radiation field , the linear accelerator Iview-GT system with the same method was shot in rectangular field simulator the same field number EPID image , and the TPS corresponding DRR image. Finally, we compared the measured error of the digital simulator positioning machine with the error of Iview-GT system image. Results The result of measured isocenter error of the digital simulator positioning machine was better than EPID image error (P=0.000). Conclusion The application of digital simulation positioning machine in radiation oncology can be more accurate to measure the error and correct the position deviation, however, it can also make the radiotherapy and the treatment more accurate.

Surgery-first approach using a three-dimensional virtual setup and surgical simulation for skeletal Class III correction / 대한치과교정학회지

A 19-year-old woman presented to our dental clinic with anterior crossbite and mandibular prognathism. She had a concave profile, long face, and Angle Class III molar relationship. She showed disharmony in the crowding of the maxillomandibular dentition and midline deviation. The diagnosis and treatment plan were established by a three-dimensional (3D) virtual setup and 3D surgical simulation, and a surgical wafer was produced using the stereolithography technique. No presurgical orthodontic treatment was performed. Using the surgery-first approach, Le Fort I maxillary osteotomy and mandibular bilateral intraoral vertical ramus osteotomy setback were carried out. Treatment was completed with postorthodontic treatment. Thus, symmetrical and balanced facial soft tissue and facial form as well as stabilized and well-balanced occlusion were achieved.