To observe the efficacy of BISCOVER LV tooth liquid polish sealant and Tooth Mousse Dental protective agent on mineralization around the orthodontic brackets during orthodontic treatment.

60 teeth with bonded orthodontic brackets were randomly divided into three groups, experimental group, positive control group and negative control group, they were applied separately with tooth liquid polish sealant, Tooth Mousse and distilled water. 3 groups were dipped into an artificial caries solution and an artificial saliva solution, cycling between them.90 days later,the changes of enamel surface around the brackets of all samples were detected by microhardness tester and scanning electron microscope.

One -way ANOVA was used for statistical analyses, there was significant difference of the microhardness of acid etched enamel surface among the three groups (P＜0.05). Through the LSD-t test, there was no significant difference of the microhardness of acid etched enamel surface between experimental group and positive control group (P＞0.05), and there were significant differences of the microhardness of acid etched enamel surface in another two comparisons within the three groups (P＜0.05). A large number of deposits were found through scanning electron microscope on the dental enamel surface of the experimental group, which could make a better remineralization.

Both BISCOVER LV tooth liquid polish sealant and Tooth Mousse Dental protective agent can effectively prevent tooth enamel from demineralization around the bracket during orthodontic treatment, doctors can choose them in accordance with the compliance of the patient.

To compare the staining effect of coffee and red tea to the different denture base materials, and to investigate the cleaning efficacy of four denture cleansers.

All samples were separately soaked in 1%NaClO、Efferdent、Polident partial and Polident overnight for 12 times within 12 days after staining by the coffee and red tea. Then, the color values of the samples were measured by the spectrocolorimeter.

The staining effect between coffee and red tea in the two materials was statistically significant (P < 0.05); the invisible denture materials are easily colored than heat-curing denture base resins (P < 0.05); there was also a statistical difference in the cleaning effect of the denture cleaning agents at each cycle stage (P < 0.05); the trend is different in different phases of color difference (ΔE) (P < 0.05).

Compared with the Polident partial, the cleaning efficacy of 1%NaClO、Efferdent and Polident overnight were better.