OBJECTIVEWe aim to evaluate the cytotoxicity and antibacterial effects of Silagum-Comfort (SLC) silicone-based soft liner varnish containing Ag/TiO2 in vitro.

METHODSSilicone-based liner circular specimens, with a diameter of 10 mm and a thickness of 2 mm, were created and divided into six groups randomly. Ag/TiO2 was incorporated into the SLC varnish based on the agent/material weight rate of 0, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%. The mixed varnish was used to polish the SLC specimens. Antibacterial specimens (ATSLC) were created. Methyl thiazolyl diphenyl-tetrazolium bromide assay method was used to evaluate the 3T3 cell cytotoxicity of ATSLC in vitro. Surface roughness (Ra) measurements of ATSLC were obtained. The antibacterial effect of ATSLC on Candida albicans was examined using the pelliclesticking method.

RESULTSThe cytotoxicity of ATSLC was graded from 0 to 2. The Ra of ATSLC increased when Ag/TiO2 agent concentration increased. However, the differences were not statistically significant compared with the 0 group. With increasing Ag/TiO2 concentration, the antibacterial agent concentration and the antibacterial rate of ATSLC also increased. When the Ag/TiO2 antibacterial agent concentration reached 2.0% and 2.5%, the antibacterial rate increased to 97.5% and 96.5, respectively.

CONCLUSIONVarnish containing Ag/TiO2 has excellent antibacterial effect and can significantly improve the antibacterial effect of silicone-based soft liner.

Anti-Bacterial Agents ; Candida albicans ; In Vitro Techniques ; Paint ; Silicones ; Titanium

OBJECTIVETo compare shear bond strength (SBS) between two types of silicone soft liner and polymethyl methacrylate (PMMA) under the condition of heat curing and room temperature curing.

METHODSA total of 48 PMMA specimens (50 mm x 10 mm x 3 mm) were made by water-bath heating method, and randomly divided into four groups. By using Ufi Gel P (UGP) as soft liner material, group A1 was prepared under heat curing, and group A2 was prepared under room temperature curing. To form the other two groups, Silagum-Comfort (SLC) as soft-liner material was used. Group B1 was prepared under heat curing, and group B2 was prepared under room temperature curing. Shear bond strength (SBS) was tested by using the electronic universal testing machine. The adhesives layer and surface of silastic and PMMA were observed by optical microscope and scanning electron microscopy (SEM).

RESULTSThe SBS of groups A1, A2, B1, B2 were (2.39 +/- 0.24), (1.74 +/- 0.27), (3.09 +/- 0.26), and (2.21 +/- 0.29) MPa, respectively. Significant differences were found between A1 and A2, B1 and B2, A1 and B1, and A2 and B2 (P < 0.05). Optical microscope showed numerous bubbles in the cured UGP, and no air bubbles in the SLC. The surface of PMMA was rough. SEM images showed that each group had continual consistent adhesive interface and a whisker hump on the adhesive layer of A2 and B2.

CONCLUSIONThe SBS ofUGP, SLC, and PMMA achieved minimum clinical standard of 0.44 MPa. The SBS of UGP and PMMA were higher than that of SLC and PMMA. The polymerization method of heat curing was higher than room temperature curing.

Dental Bonding ; Denture Liners ; Dimethylpolysiloxanes ; Materials Testing ; Polymerization ; Polymethyl Methacrylate ; Silicone Elastomers ; Silicones ; Tensile Strength

Objective:To evaluate the cytotoxicity of colorized zirconia ceramics.Methods:Zirconia ceramic 3Y-TZP blocks were colorized by NH4 VO3 ,FeCl3 ,Co(NO3 )3 ,Ni(NO3 )3 and MoCl3 respectively.The cytotoxicity of colorized zirconia to L-929 cells was examined by immersion method and MTT assay.Results:During 3 days culture,L929 cells in all groups showed similar prolifera-tion and normal morphology.The toxicity gradation of all groups was 0 -I.Conclusion:Zirconia ceramics colorized with the 5 kinds of colorants has no cytotoxicity.

94 cases with 148 abutments treated by all-ceramic restoration in premaxillary teeth region were randomly divided into 4 groups, and the impressions were prepared by one-step method,double curettage method,double polish method and double microfilm method respec-tively using 3M ESPE Vinyl polysiloxane as impression material.The cervical margin precision of the impressions was compared.Four kinds of impression method can produce qualified impression.Double polish method is easy to teach and learn.

Objective : To prepare the La-doped TiO2 film on the surface of 3Y-TZP ceramics in order to observe its antibacterial properties, providing an experimental basis for the application of antibacterial zirconia ceramics in the clinic. Method: A cylindrical 3Y-TZP specimen with a diameter of 20 mm and a height of 3 mm was prepared. The sol-gel method was used to prepare 1% lanthanum (La)-doped TiO2 sol, and the La-TiO2 film-3Y-TZP ceramic was prepared by dip coating on the surface of 3Y-TZP. The TiO2 thin film-3Y-TZP ceramic was prepared by adding no lanthanum nitrate solution in the same way. The surface morphology of 3Y-TZP ceramic specimens (3Y-TZP group), TiO2 thin film-3Y-TZP ceramic specimens (TiO2 film group), and La-TiO2 thin film-3Y-TZP ceramic specimens (La-TiO2 film group) was observed by scanning electron microscopy, and photocatalysis, antibacterial and cytotoxicity experiments were carried out. For the photocatalytic experiment, four specimens were randomly selected from the La-TiO2 film group and TiO2 film group to observe the degradation rate of methylene blue at different time points under sunlight. In the antimicrobial experiment, five specimens were randomly selected from the La-TiO2 film group, TiO2 film group and 3Y-TZP group. The antimicrobial activity of each group was tested using the bacteriostatic circle method, and the bacteriostatic distance of each group was compared. In the cytotoxicity experiment, three samples were randomly selected from the La-TiO2 film group, TiO2 film group and 3Y-TZP group (negative control group), and the extracts were prepared. Here, 0.064% phenol solution were served as the positive control group. Morphological observation of L-929 cells in four groups was performed after 3 d of culture. Cell viability and relative cell proliferation were measured by MTT assay. Results: La-TiO2 films with uniform distribution can be prepared on a 3Y-TZP surface by the dipping-drawing method. Photocatalytic experiments showed that the degradation rate of methylene blue in the La-TiO2 film group was (41.2 ± 1.5)% in daylight for 2 hours, which was higher than that in TiO2 film group (36.5 ± 2.4)%. A significant difference was noted between the two groups (t=3.321, P=0.016). The antimicrobial experiment showed that the antimicrobial distance of La-TiO2 group was (0.34 ± 0.08) mm, which was larger than that of TiO2 group (0.12 ± 0.02) mm. No obvious antimicrobial circle was noted in 3Y-TZP group, and the antimicrobial distance of the La-TiO2 film group was larger than that of TiO2 film group (F=63.798, P < 0.001). Cytotoxicity test showed that the relative proliferation rate of cells in La-TiO2 film group was (89.5 ± 1.3)%, and the cytotoxicity rating was grade 1. Significant differences were noted among the four groups (F=68.250, P < 0.001). Conclusion The La-doped TiO2 film can improve its photocatalytic activity and enhance the antibacterial activity of 3Y-TZP without obvious cytotoxicity.