[Evaluation of the emergency response strategies and measures on the epidemic of COVID-19 in Shenzhen, China].

Objectives: This study aimed to evaluate the effect of the strategies on COVID-19 outbreak control in Shenzhen, and to clarify the feasibility of these strategies in metropolitans that have high population density and strong mobility. Methods: The epidemic feature of COVID-19 was described by different phases and was used to observe the effectiveness of intervention. Hierarchical spot map was drawn to clarify the distribution and transmission risk of infection sources at different time points. The Susceptible-Exposed-Infectious-Asymptomatic-Recovered model was established to estimate case numbers without intervention and compare with the actual number of cases to determine the effect of intervention. The positive rate of the nucleic acid test was used to reflect the risk of human exposure. A survey on COVID-19 related knowledge, attitude and behaviors were used to estimate the abilities of personal protection and emergency response. Results: The epidemic of COVID-19 in Shenzhen experienced the rising, plateau and decline stage. The case number increased rapidly at the beginning, with short duration of peak period. Although the epidemic curve showed human-to-human transmission, the "trailing" was not obvious. From the spot map, during the intervention period, the source of infection was widely distributed. More cases and higher transmission risk were observed in areas with higher population density. After the effective intervention measures, both infection sources and the risk of transmission decreased. After compared with the estimated case numbers without intervention, actual number proved the COVID-19 control strategies were effective. The positive rate of nucleic acid test for high risk populations decreased and no new cases reported since February 16. Shenzhen citizens had high knowledge, attitude and behavior level, and high protection ability and emergency response. Conclusions: Although the response initiated by the health administration department played a key role at the early stage of the epidemic, it was not enough to contain the outbreak of COVID-19. The first-level emergency response initiated by provincial and municipal government was effective and ensured the start of work resumption after the Spring Festival. Metropolitans like Shenzhen can also achieve the goals of strategies and measures for containment and mitigation of COVID-19.

A new approach of splint-less orthognathic surgery using a personalized orthognathic surgical guide system: A preliminary study.

The purpose of this study was to evaluate a personalized orthognathic surgical guide (POSG) system for bimaxillary surgery without the use of surgical splint. Ten patients with dentofacial deformities were enrolled. Surgeries were planned with the computer-aided surgical simulation method. The POSG system was designed for both maxillary and mandibular surgery. Each consisted of cutting guides and three-dimensionally (3D) printed custom titanium plates to guide the osteotomy and repositioning the bony segments without the use of the surgical splints. Finally, the outcome evaluation was completed by comparing planned outcomes with postoperative outcomes. All operations were successfully completed using the POSG system. The largest root-mean-square deviations were 0.74mm and 1.93° for the maxillary dental arch, 1.10mm and 2.82° for the mandibular arch, 0.83mm and 2.59° for the mandibular body, and 0.98mm and 2.45° for the proximal segments. The results of the study indicated that our POSG system is capable of accurately and effectively transferring the surgical plan without the use of surgical splint. A significant advantage is that the repositioning of the bony segments is independent to the mandibular autorotation, thus eliminates the potential problems associated with the surgical splint.