Temporomandibular joint positional change accompanies post‐surgical mandibular relapse—A long‐term retrospective study among patients who underwent mandibular advancement

Abstract

Objective: This study evaluated the relationship between follow-up temporomandibular joint positional change and mandibular stability among patients who had orthognathic and orthodontic treatment for a skeletal Class II malocclusion. Methods:Thirty-seven patients who underwent 2-jaw surgery (Le Fort I osteotomy, bilateral sagittal split ramus osteotomy and genioplasty with rigid internal fixation)were included with an average follow-up length of 8.10 ± 2.06 years. They were categorized into a stable and unstable group according to follow-up mandibular change in the sagittal direction. Temporomandibular joint spaces were measured on serial magnetic resonance images, prior to orthodontic treatment (T0), upon completion of orthodontic treatment following surgery (T1), and at least 5 years post-completion of the treatment (T2).Results: While the maxillary position was stable during the follow-up period, the mandibular positional change was statistically significant (the relapse amount was −0.81 ± 1.52 mm at B point). An increase in the anterior joint space and superior joint space was found to correlate with the follow-up mandibular backward movement. Conclusions:Patients who underwent orthognathic and orthodontic treatment to correct mandibular retrognathism displayed follow-up mandibular relapse in the sagittal direction. The relapse is accompanied by condylar positional change. K E Y W O R D Sangle class II, malocclusion, mandibular advancement, mandibular reconstruction, orthognathic surgery, temporomandibular joint

Eleven‐year experience implementing a dental undergraduate research programme in a prestigious dental school in China: Lessons learned and future prospects

“…In past studies, undergraduates who participated in a research programme were equipped with a better self‐evaluation of designing research projects, using statistical software, making figures and charts, evaluating experimental results and performing experiments than those who did not 8 . Undergraduate research participants have an improved comprehensive scientific research ability necessary for the medical research process, publish more articles and earn a significantly higher cumulative grade point average (CGPA) or overall GPA 1,8,12,33‐35 . The research requirement had a positive effect on students' perspectives on research as a part of their careers 6,36 .…”

Deep Learning for Fast and Spatially Constrained Tissue Quantification From Highly Accelerated Data in Magnetic Resonance Fingerprinting

“…In the Supplementary Materials, we further study this blurriness through frequency-domain representations of the quantitative maps. The blurring effect of our method potentially degrades spatial resolution and hinders application for high-resolution imaging [36]- [39]. To tackle with this problem, a loss function can be added to enhance the high frequency details of our output tissue property map, such as a discriminative loss within generative adversarial networks (GAN) [40]- [42], or a gradient loss that minimizes the difference between the gradient maps of network output and the ground-truth tissue property map [42], [43].…”

Three-dimensional planning accuracy and follow-up protocol in orthognathic surgery: a validation study

“…Recent methods applied in orthognathic surgery are more focused towards the planning aspect and no 3D protocol exists for objective quantification of long-term postoperative follow-up. Relapse studies have either been based on 2D or 3D cephalometry 15,16 carrying the risk of human error. Literature lacks evidence on the availability of a time-efficient and a solely software-based protocol for analysing the 3D movements in orthognathic surgery.…”