Objective:To learn from the experiences of environmental impact assessment,and explore the theories and practices of health impact assessment.Methods:With suitability analysis of reference to environmental impact assessment and literature research,the current situation,practices and problems of environmental impact assessment were summarized.Results and Conclusion:Drawing on experiences in environmental impact assessment,it needed to start the establishment and implementation of health impact assessment system with healthy cities,healthy towns and villages,improve relevant laws and regulations,strengthen supervision and management of health impact assessment.

Objective: To investigate the infection status and genotype distribution of cervical human papillomavirus (HPV) in women of different ethnic groups and different ages in Yili, Xinjiang Uygur Autonomous Region (Xinjiang). Methods: By using the convenient sampling method, 54 760 women from November 2015 to May 2017 seeking for service in gynecological clinics in a general hospital in Yili, Xinjiang, were selected as the research subjects, and 3 445 samples of cervical mucous exfoliative cells were collected, and the social information of their ethnic and age was collected at the same time. The inclusion criteria were those with sexual life, cervical integrity, and ethnic groups for Han or Uygur or Kazak. PCR-reverse dot blot hybridization was used to detect HPV genotyping in exfoliated cells, and chi-square test was used to compare the difference of HPV positive rate among different ethnic groups. Then, according to ethnicity and age, the differences in positive rates of different ages and ethnic groups were compared in each layer. Results: The positive rate of HPV was 25.6% (882 cases), of which the Han, Uygur and Kazakh were 27.9% (564 cases), 22.9% (196 cases) and 21.6% (122 cases), and the difference was statistically significant (χ²=13.80, P=0.001). The most prevalent high-risk genotypes of Han women were HPV16/52/58, accounting for 24.8% (140 cases), 17.7% (100 cases) and 9.8% (55 cases), respectively. The most prevalent high-risk genotypes of Uygur women were HPV16/52/53, accounting for 34.2% (67 cases), 12.8% (25 cases), 9.2% (18 cases), respectively. The most prevalent high-risk genotypes of Kazak were HPV16/52/53, accounting for 37.7% (46 cases), 17.2% (21 cases), 12.3% (15 cases), respectively. The highest rate of HPV in Uygur patients aged ≥61 years was 41.5% (22 cases), and the lowest in group 36-40 years old, 15.9% (21 cases), the difference between different age groups was statistically significant (χ²=35.01, P<0.001). Conclusion The positive rate of HPV infection among Han, Uygur and Kazak in Yili Prefecture of Xinjiang was different, and the HPV positive genotype differs among different ethnic groups.

Postzygotic mutations are acquired in normal tissues throughout an individual's lifetime and hold clues for identifying mutagenic factors.Here,we investigated postzygotic mutation spectra of healthy individuals using optimized ultra-deep exome sequencing of the time-series samples from the same volunteer as well as the samples from different individuals.In blood,sperm,and muscle cells,we resolved three common types of mutational signatures.Signatures A and B represent clock-like mutational processes,and the polymorphisms of epigenetic regulation genes influence the pro-portion of signature B in mutation profiles.Notably,signature C,characterized by C＞T transitions at GpCpN sites,tends to be a feature of diverse normal tissues.Mutations of this type are likely to occur early during embryonic development,supported by their relatively high allelic frequencies,presence in multiple tissues,and decrease in occurrence with age.Almost none of the public datasets for tumors feature this signature,except for 19.6％of samples of clear cell renal cell carcinoma with increased activation of the hypoxia-inducible factor 1(HIF-1)signaling pathway.Moreover,the accumulation of signature C in the mutation profile was accelerated in a human embryonic stem cell line with drug-induced activation of HIF-1α.Thus,embryonic hypoxia may explain this novel signature across multiple normal tissues.Our study suggests that hypoxic condition in an early stage of embryonic development is a crucial factor inducing C＞T transitions at GpCpN sites;and indi-viduals'genetic background may also influence their postzygotic mutation profiles.

Objective To investigate the biomechanical effects of lingual metal-reinforced denture bases on edentulous implant-supported prostheses by three-dimensional finite element analysis,and provide references for the treatment of edentulous jaws.Methods Two implant-supported Locator-type overdenture models with lingual metal-reinforced and non-reinforced denture bases were constructed.A 150 N vertical load on the fovea of the posterior teeth,a 150 N oblique load on the fovea of the posterior teeth,and a 150 N vertical load on the anterior teeth were applied to simulate the centric occlusion,left and right lateral chewing,and anterior teeth cutting,and stresses on the tissues of two models were analyzed.Results When the posterior and anterior teeth were loaded vertically,the stress distribution on each organization was similar between the two denture base designs.The maximum stress difference was between 0 and 0.16 MPa.Under unilateral masticatory chewing,the range of stress concentration on denture base,implant and mucoperiosteum,and the maximum stress of the implant and peri-implant bone without metal reinforcement were significantly greater than those with metal reinforcement,and the maximum stress difference was between 0.59 MPa and 2.99 MPa.Conclusions Lingual metal-reinforced denture base can play a role in stress dispersion,or reduce the risk of bone resorption and denture base fracture to a certain extent.

Computer aided design, numerically controlled milling, additive manufacturing and other digital technologies have been widely used in clinical practice of prosthodontics. The application of these technologies not only changed the design and manufacturing workflow of removable partial denture (RPD), but also improved the production efficiency of dentures, and changed the design and manufacturing concept of dentures. A large number of researches on computer aided design and computer aided manufacturing (CAD/CAM) of RPD have emerged in recent years, including researches on the properties of selective laser melting metal powder and other new dental materials, the innovative design of retainers, connectors, artificial teeth and other denture components, high precision manufacturing of the RPD framework, denture base and artificial teeth, quantitative laboratory evaluations of the accuracy, adaption and mechanical properties of RPD with new structures and made of new materials, clinical evaluations of RPD and others. This paper introduces these recent developments in CAD/CAM of RPD.

Objective:To quantitatively evaluate the accuracy of multi-color and multi-hardness dental models printed by using the photopolymer jetting (PJ) technology, and to provide protocol for the clinical application.Methods:A maxillary partially edentulous (Kennedy class Ⅱ subclass 1) standard digital model obtained through scanning and processing was selected as reference data. Five monochromatic DLP (digital light processing) models with single hardness were printed by printer DLP-800d based on DLP technology (DLP group), and five multi-color and multi-hardness PJ models were printed by printer J300Plus based on PJ technology (PJ group). Scan the printed model and register the scanning data to the reference data in Geomagic Studio 2013 software. The three-dimensional (3D) deviations of the whole and each area, including residual dentition, abutments adjacent to the edentulous area, gingiva, gingiva in the distal-extended edentulous area, gingiva in other edentulous areas, gingiva supporting the removable partial denture (RPD), were calculated and represented by the root mean square error (RMS) value. The smaller the RMS value was, the higher the trueness of printing was. The scanning data of the five models in the same group were registered in pairs to calculate the 3D deviation. The smaller the RMS value was, the higher the precision of printing was. The threshold of clinical acceptability was 200 μm. Statistical analysis was performed to compare the difference of trueness and precision between the two groups.Results:The overall trueness of the DLP group [57.70 (2.10) μm] was significantly better than that of the PJ group [71.00 (7.70) μm]. The overall precision of the DLP group [15.20 (5.05) μm] was significantly better than that of the PJ group [37.55 (15.55) μm]. The overall trueness and precision of both groups were within the clinically acceptable range.Conclusions:The domestic PJ printer used in this study can print multi-color and multi-hardness dental models with good trueness and precision, which can provide integrated 3D printing technology support for realizing the simulation of regional hardness differentiation between soft and hard tissues of dental models.