Objective:To investigate the effects of different post space parameters and scanning aid material on the trueness of digital impressions of post spaces obtained by two intraoral scanners, thereby providing a reference for clinically determining the conditions under which post spaces are suitable for digital impression technology.Methods:This study varied three variables of post space models of residual crowns: opening diameter, post space depth and adjacent tooth status,with specific settings: opening diameter were set at two levels (2.0 and 2.5 mm);post space depth was set at three levels (8.0, 10.0, and 12.0 mm); and adjacent tooth status were set at three levels [bilateral adjacent teeth present (A), unilateral adjacent tooth present (B), and bilateral adjacent teeth absent (C)]. A total of 18 model groups were prepared. Eighteen samples were printed using a three-dimensional printing instrument. Combined with scanning aid material, direct in vitro scanning of these post space models was performed using intraoral scanners (IOS) A (Trios 5) and B (Primescan connect), with 10 replicates per group ( n=10). The scanned data were sequentially imported into reverse engineering software. The original design data of the models served as true values, and best-fit comparisons were performed. By calculating the average root mean square error (RMSE) values, the trueness of digital impressions of post spaces with different morphologies obtained by the two scanners was evaluated, both with and without the use of scanning aid material. Results:Under the experimental conditions set in this study, for IOS A, only the sample groups with opening diameter-post space depth-adjacent tooth status combinations of (2.0-8.0-ABC, 2.5-8.0-ABC, 2.5-10.0-ABC) could be identified, with RMSE results ranging from 46.5 to 365.0 μm. After adding scanning aid materials,RMSE results ranging from 46.0 to 185.0 μm, the trueness of the sample groups (2.0-8.0-A, 2.5-10.0-A) was significantly improved by more than 100 μm, and an additional sample group (2.5-12.0-C) could be identified. For IOS B, the identifiable sample groups included all 18 sample groups, with RMSE results ranging from 38.8 to 106.0 μm. After the addition of scanning aid materials, RMSE results ranging from 37.6 to 110.2 μm, the identifiable sample groups remained unchanged. Post space opening diameter, post space depth, and adjacent tooth status all had significant effects on the trueness of post space digital impressions for both IOS A and IOS B (all P<0.05). Scanning aid materials had a significant effect on IOS A ( P<0.05), but no significant effect on IOS B ( P>0.05). Conclusions:IOS B exhibited superior post space scanning performance compared to IOS A, and its trueness for clinically common post spaces could meet clinical requirements. IOS A has certain requirements for post space opening diameter, post space depth, and adjacent tooth status. For narrow and long post spaces, scanning aid materials can be used to improve the scanning trueness.

Objective:To investigate the effects of different post space parameters and scanning aid material on the trueness of digital impressions of post spaces obtained by two intraoral scanners, thereby providing a reference for clinically determining the conditions under which post spaces are suitable for digital impression technology.Methods:This study varied three variables of post space models of residual crowns: opening diameter, post space depth and adjacent tooth status,with specific settings: opening diameter were set at two levels (2.0 and 2.5 mm);post space depth was set at three levels (8.0, 10.0, and 12.0 mm); and adjacent tooth status were set at three levels [bilateral adjacent teeth present (A), unilateral adjacent tooth present (B), and bilateral adjacent teeth absent (C)]. A total of 18 model groups were prepared. Eighteen samples were printed using a three-dimensional printing instrument. Combined with scanning aid material, direct in vitro scanning of these post space models was performed using intraoral scanners (IOS) A (Trios 5) and B (Primescan connect), with 10 replicates per group ( n=10). The scanned data were sequentially imported into reverse engineering software. The original design data of the models served as true values, and best-fit comparisons were performed. By calculating the average root mean square error (RMSE) values, the trueness of digital impressions of post spaces with different morphologies obtained by the two scanners was evaluated, both with and without the use of scanning aid material. Results:Under the experimental conditions set in this study, for IOS A, only the sample groups with opening diameter-post space depth-adjacent tooth status combinations of (2.0-8.0-ABC, 2.5-8.0-ABC, 2.5-10.0-ABC) could be identified, with RMSE results ranging from 46.5 to 365.0 μm. After adding scanning aid materials,RMSE results ranging from 46.0 to 185.0 μm, the trueness of the sample groups (2.0-8.0-A, 2.5-10.0-A) was significantly improved by more than 100 μm, and an additional sample group (2.5-12.0-C) could be identified. For IOS B, the identifiable sample groups included all 18 sample groups, with RMSE results ranging from 38.8 to 106.0 μm. After the addition of scanning aid materials, RMSE results ranging from 37.6 to 110.2 μm, the identifiable sample groups remained unchanged. Post space opening diameter, post space depth, and adjacent tooth status all had significant effects on the trueness of post space digital impressions for both IOS A and IOS B (all P<0.05). Scanning aid materials had a significant effect on IOS A ( P<0.05), but no significant effect on IOS B ( P>0.05). Conclusions:IOS B exhibited superior post space scanning performance compared to IOS A, and its trueness for clinically common post spaces could meet clinical requirements. IOS A has certain requirements for post space opening diameter, post space depth, and adjacent tooth status. For narrow and long post spaces, scanning aid materials can be used to improve the scanning trueness.

Objective:To evaluate the clinical efficacy of microneedle radiofrequency in the treatment of moderate acne vulgaris.Methods:From August 2018 to August 2020, 393 patients (192 males and 201 females, aged 15-38 years) with moderate acne were enrolled in the Department of Dermatology, the First Affiliated Hospital of Shantou University Medical College and Shantou Chaonan Minsheng Hospital, including 201 patients in experimental group and 192 patients in control group. In the experimental group, microneedle radiofrequency therapy was used once every 2 weeks for 3 times in total. The control group adopted the fire needle, once every 2 weeks, a total of 3 times. The efficacy of both groups was evaluated at week 8.Results:A total of 378 patients were actually completed: 196 patients in the experimental group, and 182 patients in the control group. At the eighth week of follow-up, the total effective rate was 81.12% in the experimental group and 70.43% in the control group. The efficacy of the two groups was statistically different (χ 2=4.42, P<0.05). Conclusions:The efficacy of microneedle radiofrequency therapy in the treatment of moderate acne vulgaris is better than that of fire needle, with good tolerance, short recovery period, few adverse reactions and high compliance, which has clinical promotion value.

Objective : To explore the technology and efficacy of fabrication of a guide and removal of a fiber post by tetrahedron positioning technology at the chair side. Methods: For one patient with acute chronic periapical periodontitis of the left maxillary lateral incisor who needed to have the fiber post removed, the chair side tetrahedral positioning technique was used to make a guide plate to remove the fiber post. Cone beam CT (CBCT) data were imported into the software to design the guide plate for fiber post removal. The guide plate design on CBCT was transferred to a solid model by using tetrahedral positioning technology. The guide plate was made to guide the removal of the fiber post, and then left maxillary lateral incisor root canal was performed. We evaluated the effect of fiber post removal with tetrahedral positioning technology by reviewing the literature. Results : The guide plate made by tetrahedral positioning technology can accurately locate the position and direction of fiber posts at a low cost and with high speed. After the fiber post was removed, the root canal could be dredged by using root canal preparation instruments. After root canal preparation, the root canal was filled with warm gutta-percha to complete the root canal treatment. After 3 months, the apical radiograph showed that the transmission shadow of the apical area was reduced. The results of the literature review showed that the fiber post removal with guide plates provides a predictable result and a lower risk of iatrogenic damage. Minimally invasive treatment can be carried out, and chair time can be reduced. Conclusion On the basis of CBCT data, using tetrahedral positioning technology to make fiber post removal guides can help reduce the risk of fiber post removal and has the characteristics of speed, low cost and short chair side processing. However, the accuracy comparison between tetrahedral positioning technology and 3D printing guides needs further study.

Objective:To study the cellular pathology and molecular mechanisms of intestinal mucosal damage induced by IgG immune complex in mice.And to explore the pathogenic mechanism and molecular diagnosis evidence of ulcerative colitis induced by food intolerance in clinical practice.Methods: Six weeks old BALB/c female mice were used to build animal model.All the mice were divided into four groups:the control group(group A),the rabbit intestinal mucosal protein immunized group(group B),the DSS induced group(group C),the rabbit intestinal mucosal protein immunized combined with DSS induced group(group D).After successful establishment of animal model,serum and colon tissues were collected to be performed relevant tests.Results: IgG level in serum and colonic mucosa of group B mice increased.And inflammatory cell infiltration and a small amount of mast cell activation were observed in intestinal mucosa;group C mice showed the typical acute ulcerative colitis:a large number of inflammatory cells infiltration,inflammatory factor levels increased in mucosa and mucosa lamina propria,and mucosal epithelial cells′ tight junction weakened;group D mice manifested both high level of IgG in serum and colonic mucosa and also typical acute ulcerative colitis.Besides,significant mast cell activation was observed in the intestinal mucosa.Conclusion: We infer from the experimental results that IgG immune complexes can induce the damage of intestinal epithelium by mediating activation of mast cells.And during the process,the level of inflammatory cytokines increased in intestinal mucosa and the expression of tight junction protein in epithelial cell decreased.These factors contribute to the promotion of intestinal mucosa damage induced by immune complexes.