Influence of resin modified glass ionomer cement incorporating protein-repellent and antimicrobial agents on supragingival microbiome around brackets: an in-vivo split-mouth 3-month study.

Objective: To explore the influence of resin modified glass ionomer cement (RMGIC) adhesives containing protein-repellent and quaternary ammonium salt agents on supragingival microbiome, enamel and gingival health around brackets. Materials and Methods: Ten patients (21.4 ± 3.5 years) about to receive fixed orthodontics were enrolled in this study. Unilateral upper teeth bonded with RMGIC incorporating 2-Methacryloyloxyethyl phosphorylcholine (MPC) and Dimethylaminohexadecyl methacrylate (DMAHDM) were regarded as experimental group (RMD), while contralateral upper teeth bonded with RMGIC were control group (RMGIC), using a split-mouth design. Supragingival plaque was collected from both groups before treatment (T0), and at 1 month (T1) and 3 months (T2) of treatment. High-throughput sequencing was performed targeting v3-v4 of 16S rRNA gene. Streptococcus mutans and Fusobacterium nucleatum quantification was done by qPCR analysis. Bracket failures, enamel decalcification index (EDI), DIAGNODent scores (Dd), plaque index (PI) and gingival index (GI) were monitored at indicated time points. Results: Within 3 months, alpha and beta diversity of supragingival plaque had no difference between RMGIC and RMD groups. From T0 to T2, the relative abundance of Streptococcus depleted in RMD but remained steady in RMGIC group. Streptococcus, Prevotella, and Fusobacterium became depleted in RMD, Haemophilus and Capnocytophaga became depleted in RMGIC group but Prevotella enriched. Quantification of Fusbacterium nucleatum and Streptococcus mutans showed significant difference between RMGIC and RMD groups at T2. Teeth bonded with RMD had significant lower plaque index (PI) and DIAGNODent (Dd) score at T2, compared with teeth bonded with RMGIC (p < 0.05). No difference in bracket failure rate was examined between both groups (p > 0.05). Conclusion: By incorporating MPC and DMAHDM into RMGIC, the material could affect the supragingival microbial composition, inhibit the progress of plaque accumulation as well as the key pathogens S. mutans and F. nucleatum in the early stage of orthodontic treatment.

[Rapid determination of trace volatile organic compounds in ambient air by portable gas chromatography-mass spectrometry].

OBJECTIVE: Direct determination of 35 trace volatile organic compounds in air by portable gas chromatography mass spectrometry( GC-MS). METHODS: The mixed standard gas of different concentration levels was prepared with high purity nitrogen as diluent gas. The samples were injected into the GC-MS by a hand-held probe. Retention time and characteristic ion were used for qualitative analysis, and the internal standard method was usd for quantitation. RESULTS: Under the established experimental conditions, the 35 poisonous substances were separated and determined well. The relative standard deviation was 3. 2%-15. 1%. The average recovery was 75. 1%-121. 4%( n = 6). CONCLUSION: The portable GC-MS method can be used for qualitative and quantitative detection of volatile organic compounds in ambient air.

[Spectrometric determination of the content of nutritional elements in fruits of different red pear varieties].

A study was carried out on the contents of nutritional elements such as K, Fe, Zn, Ca, Cu, Mg and Mn in three different red pear varieties, namely Meirensu, Hongsucui and Mantianhongs, by flame atomic absorption. The results indicated that the linear relationships for different elements within the limits of working curves are good, and the range of recovery is 98%-104%, hence showing that the results asre satisfactory. There are abundant nutritional elements in fruits of the three different red pear varieties, meaning that they all have a relatively high nutritive value. In fruits of the three red pear varieties, the content sequence of different nutritional elements was found to be K>Fe>Zn>Ca>Cu>Mg>Mn. In fruits of the three different red pear varieties, the content sequence of K, Zn, Mg and Mn was Meirensu> Hongsucui>Mantianhong; the content sequence of Fe and Cu was Hongsucui>Mantianhong>Meirensu; and the content sequence of Ca was Mantianhong>Hongsucui> Meirensu; and the total content sequence of seven nutritional elements was Hongsucui>Meirensu>Mantianhong.