Assessment of Masseter Volume and Postoperative Stability After Orthognathic Surgery in Patients With Skeletal Class III Malocclusion With Facial Asymmetry.

OBJECTIVE: This study aimed to evaluate the effect of orthognathic surgery on masseter volume in patients with skeletal Class III malocclusion with facial asymmetry and the effect of masseter volume on stability in orthognathic surgery. METHODS: This research studied 16 patients with Class III malocclusion with facial asymmetry who received combined orthodontic-orthognathic treatment and underwent craniofacial computed tomography (CT) before (T0), 2 weeks after (T1), and 6 months after (T2) surgery. Three-dimensional (3D) CT images were retrospectively analyzed, using 3D volume reconstruction to obtain the masseter volume and examine the impact of the masseter volume on stability in orthognathic surgery. RESULTS: A statistically significant difference ( P < 0.05) in the volume of the masseter was found up to 6 months after orthognathic surgery compared with the preoperative period, and the reduction in the masticatory muscle volume on the lengthened side is greater than on the shortened side ( P < 0.05). The volume of both masseters differed according to facial asymmetry, and the difference was significantly reduced after orthognathic surgery ( P < 0.05). During the period time (T1-T2), cephalometric maxillary marker points were not significantly different ( P > 0.05), and mandibular marker points were significantly anteriorly shifted ( P < 0.05). There was an association between the masseter volume and anterior shift of point B (R > 0.5, P < 0.05), the upward and anterior shifts of the gonion point differed between the lengthened and shortened sides ( P < 0.05). CONCLUSION: The size of the masseter becomes smaller 6 months after orthognathic surgery, and orthognathic surgery improves both bone and soft tissue symmetry. A larger sagittal relapse of mandibular setback occurred in patients with greater masseter volume. Considering these alterations may be helpful in planning orthognathic surgery.

Structural effects of provincial digital economy on carbon emissions within China: A multi-region input-output based structural decomposition analysis.

The digital economy, serving as a new engine to boost China's economic growth, inevitably affects carbon emissions given both its green features and its potential demands for energy inputs. To investigate the province-level impacts of the digital economy on carbon emissions, this study splits the digital industry from the multi-regional input-output table, and adopts a downscale structural decomposition analysis to reveal the technological, structural, and scale effects of the digital economy on carbon emissions. The results show that: (1) the expansion of digital economy increased 186.3 Mt of carbon emissions at the aggregate level during the investigated period (2012-2017) and that, therefore, the direct structural effects of the digital economy played a leading role in emission reduction (-156 Mt); (2) in terms of heterogeneity, most provinces presented a U distribution with the structural mitigation effect at the bottom and highly-developed provinces generated significant negative spillover effects; (3) from a regional coordination perspective, digital production achieved greater carbon emission reductions in the eastern and western areas of the country, while the northeastern and central regions gained environmental benefits via digital applications. The main conclusions thus enhance existent understanding of China's digital economy and low-carbon development, and the paper also proffers corresponding policy recommendations, e.g., accelerating the convergence of digital economy and traditional industries to promote carbon emissions reduction.