[Effect of bleaching combined with Er:YAG or Nd:YAG laser on shear bond strength and microleakage of resin restoration].

PURPOSE: To evaluate the effects of bleaching combined with Er:YAG laser or Nd:YAG laser on bond strength and microleakage of resin fillings on enamel surface. METHODS: Sixty-four pieces of enamel specimens prepared from isolated teeth were randomly divided into 4 groups(n=16): control group, simple bleaching group, bleaching combined with Er: YAG laser group and bleaching combined with Nd:YAG laser group. Then the shear bond strength and the depth of microleakage were tested, and the fracture mode of the specimen was observed under microscope. SPSS 26.0 software package was used for statistical analysis. RESULTS: After bleaching simply, the bond strength of the restoration was significantly decreased, and the marginal microleakage was significantly increased(P＜0.05). There was no significant difference in shear bond strength and microleakage depth between the group bleaching combined with Er: YAG laser and control group(P＞0.05). The shear bond strength after bleaching combined with Nd:YAG laser was significantly reduced (P＜0.05), but there was no significant difference in the depth of microleakage compared with unbleached microleakage(P＞0.05). Bonding interface fracture was the main fracture mode for all groups. CONCLUSIONS: Compared to traditional bleaching, bleaching combined with laser has certain clinical advantages due to its less influence on bond strength and microleakage of resin fillings.

Osteomodulin protects dental pulp stem cells from cisplatin-induced apoptosis in vitro.

Human dental pulp stem cells (hDPSCs) are considered promising multipotent cell sources for tissue regeneration. Regulation of apoptosis and maintaining the cell homeostasis is a critical point for the application of hDPSCs. Osteomodulin (OMD), a member of the small leucine-rich proteoglycan family, was proved an important regulatory protein of hDPSCs in our previous research. Thus, the role of OMD in the apoptosis of hDPSCs was explored in this study. The expression of OMD following apoptotic induction was investigated and then the hDPSCs stably overexpressing or knocking down OMD were established by lentiviral transfection. The proportion of apoptotic cells and apoptosis-relative genes and proteins were examined with flow cytometry, Hoechst staining, Caspase 3 activity assay, qRT-PCR and western blotting. RNA-Seq analysis was used to explore possible biological function and mechanism. Results showed that the expression of OMD decreased following the apoptotic induction. Overexpression of OMD enhanced the viability of hDPSCs, decreased the activity of Caspase-3 and protected hDPSCs from apoptosis. Knockdown of OMD showed the opposite results. Mechanistically, OMD may act as a negative modulator of apoptosis via activation of the Akt/Glycogen synthase kinase 3ß (GSK-3ß)/ß-Catenin signaling pathway and more functional and mechanistic possibilities were revealed with RNA-Seq analysis. The present study provided evidence of OMD as a negative regulator of apoptosis in hDPSCs. Akt/GSK-3ß/ß-Catenin signaling pathway was involved in this process and more possible mechanism detected needed further exploration. This anti-apoptotic function of OMD provided a promising application prospect for hDPSCs in tissue regeneration.

[Correlation analysis of supragingival microbiome and host blood lipid levels].

PURPOSE: To analyze the correlation between microbiome of supragingival plaque and host blood lipid levels. METHODS: Samples of supragingival plaques from 68 volunteers aged 45-60 years were collected. The total DNA was extracted, and 16S rDNA V3-V4 regions were amplified via PCR. The amplified products were sequenced by Illumina MiSeq PE300. After that, OTU clustering and species annotation were carried out. Then, the correlation of annotated species (genus level) and host blood lipid level were calculated with Spearman correlation analysis. SPSS 16.0 software package was used for statistical analysis. RESULTS: The average number of sequences obtained from the supragingival plaque samples was 41 929, and the number of OTUs obtained by clustering was 1 037. A total of 25 phyla, 45 classes, 92 orders, 155 families and 330 genera were annotated. Species heat maps showed a high degree of consistency in the species composition abundance of 68 samples. Spearman correlation analysis showed that among the supragingival microorganisms, Alloprevotella spp., Dialister spp., Peptostreptococcus spp. and Prevotella 7 spp., were negatively correlated with the host serum total cholesterol/low density lipoprotein cholesterol level. Neisseria spp. was positively correlated with host serum high-density lipoprotein cholesterol, but negatively correlated with Prevotella 2 spp.. CONCLUSIONS: The compositional structure of the supragingival microbiome is relatively stable and has a correlation with the host blood lipid levels. Profiles of supragingival microbiome can be promising biomarkers of the lipid metabolism of the host.

Shifts in the Bacterial Community of Supragingival Plaque Associated With Metabolic-Associated Fatty Liver Disease.

Metabolic-associated fatty liver disease (MAFLD), also known as the hepatic manifestation of metabolic disorders, has become one of the most common chronic liver diseases worldwide. The associations between some oral resident microbes and MAFLD have been described. However, changes to the oral microbial community in patients with MAFLD remain unknown. In this study, variations to the supragingival microbiota of MAFLD patients were identified. The microbial genetic profile of supragingival plaque samples from 24 MAFLD patients and 22 healthy participants were analyzed by 16S rDNA sequencing and bioinformatics analysis. Clinical variables, including indicators of insulin resistance, obesity, blood lipids, and hepatocellular damage, were evaluated with laboratory tests and physical examinations. The results showed that the diversity of the supragingival microbiota in MAFLD patients was significantly higher than that in healthy individuals. Weighted UniFrac principal coordinates analysis and partial least squares discriminant analysis showed that the samples from the MAFLD and control groups formed separate clusters (Adonis, P = 0.0120). There were 27 taxa with differential distributions (linear discriminant analysis, LDA>2.0) between two groups, among which Actinomyces spp. and Prevotella 2 spp. were over-represented in the MAFLD group with highest LDA score, while Neisseria spp. and Bergeyella spp. were more abundant in the control group. Co-occurrence networks of the top 50 abundant genera in the two groups suggested that the inter-genera relationships were also altered in the supragingival plaque of MAFLD patients. In addition, in genus level, as risk factors for the development of MAFLD, insulin resistance was positively correlated with the abundances of Granulicatella, Veillonella, Streptococcus, and Scardovia, while obesity was positively correlated to the abundances of Streptococcus, Oslenella, Scardovia, and Selenomonas. Metagenomic predictions based on Phylogenetic Investigation of Communities by Reconstruction of Unobserved States revealed that pathways related to sugar (mainly free sugar) metabolism were enriched in the supragingival plaque of the MAFLD group. In conclusion, as compared to healthy individuals, component and interactional dysbioses were observed in the supragingival microbiota of the MAFLD group.

[The efficacy of cold-light tooth bleaching on the formation of bacteria biofilm on the enamel surfaces].

PURPOSE: To evaluate the efficacy of Beyond cold-light tooth bleaching on the formation of main cariogenic bacteria biofilm on enamel surfaces. METHODS: Twenty enamel discs with the size of 4 mm×4 mm×1 mm in size, were made. The enamel discs were divided into 4 groups randomly: cold-light bleaching group, bleaching gel group, cold-light group and control group. Five discs were in each group. Cold-light bleaching group was whitened 3 times with bleaching gel and cold-light, and 12 min per session. Bleaching gel was smeared on the surface of enamel in bleaching gel group for 3 times and 12 min per session. Enamel discs of cold-light group were treated with cold-light for 12 min and 3 sessions. Control group was treated without any processing. The 4 groups were incubated in mixed bacteria liquid, including Streptococcus mutans(SM), Actinomyces viscosus (Av) and Fusobacterium nucleatum (Fn), within the artificial oral cavity model. After 36 h, the samples were observed under confocal laser scanning microscopy(CLSM). The data was analyzed with SAS8.2 software package. RESULTS: The biofilms in 3 experimental groups were sparser than the control group under CLSM, and the thickness significantly decreased after treatment (P<0.05), while no significant difference was found among 3 experimental groups (P>0.05).Compared with the control group, the percentage of vital bacteria in biofilm of the experimental groups decreased significantly after treatment (P<0.001). CONCLUSIONS: Cold-light tooth bleaching can inhibit the formation of mixed bacteria biofilm, damage the structure of biofilm and reduce the number of vital bacteria. Supported by Research Fund of Ninth People's Hospital of Shanghai Jiao Tong University School of Medicine (2013-06).