Surface roughness and gloss of novel flowable composites after polishing and simulated brushing wear / 中华口腔医学杂志

Objective@#To investigate surface properties of novel flowable composites after polishing and simulated brushing wear, compared to their pasty counterpart.@*Methods@#Composites employed in this study were: three flowable composites (A1: Clearfil Majesty ES Flow; B1: Beautifil Flow Plus F00; C1: Filtek Bulk Fill) and three paste composites (A2: Clearfil Majesty; B2: Beautifil; C2: Filtek Z350. Eleven disk-shaped specimens were made for each material. The specimens were cured, then subjected to sandpaper finishing for 20 s, one-step polishing for 30 s, finally subjected to simulated brushing for 10 000 cycles. Surface roughness and glossiness were measured before finishing, after finishing, after polishing, after 5 000 brushing cycles and after 10 000 brushing cycles, respectively. Data obtained were analyzed using two-way ANOVA method. Scanning electron microscope was employed to examine the microscopic appearance of each material.@*Results@#Surface roughness (0.11~0.22 μm) and glossiness (74.25~86.48 GU) of each material were similar after one-step polishing. After brushing simulation, roughness increased significantly and glossiness decreased significantly for each material (P<0.05). Group A1 presented the best gloss ([50.68±1.58] GU) after final wear (P<0.05). Flowable composites of group A1 and B1 tested in the present setup showed better surface properties compared to their pasty counterpart (group A2 and B2).@*Conclusions@#Within the limit of this study, flowable composites tested in the present research can obtain similar surface polish or even better than the paste composite counterpart.

Antibacterial effect of self-etching adhesive systems on Streptococcus mutans / 北京大学学报(医学版)

Objective:To investigate the antibacterial effect of different self-etching adhesive systems against Streptococcus mutans (S.mutans).Methods:Six reagents ClearfilTM SE Bond primer (SP), ClearfilTM SE Bond adhesive (SA),ClearfilTM Protect Bond primer (PP),which contained antibacterial monomer methacryloyloxydodecylpyridinium bromide (MDPB),ClearfilTM Protect Bond adhesive (PA), positive control chlorhexidine acetate [CHX,1% (mass fraction )],and negative control phosphate buffer solution (PBS)were selected.They were mixed with S.mutans for 30 s respectively,then colony-forming units (CFU)were counted after incubated for 48 h on brain heart infusion (BHI)agar medium. The 6 reagents were applied to the sterile paper discs,and distributed onto the BHI agar medium with S. mutans and incubated for 24 h,then the inhibition zones were observed.CHX,PBS,PP,and SP were added on the dentin with artificial caries induced by S.mutans and kept for 30 s,then confocal laser scanning microscope (CLSM)was used to observe the live and dead bacteria after staining.The ratio of live to dead bacteria was calculated.PP+PA and SP+SA were applied on the dentin according to the manual and light cured.S.mutans were incubated on the samples for 2 h,ultrasonically treated and in-cubated on BHI agar medium for 48 h,then CFU was counted.The data were analyzed by non-parametric analysis and one-way ANOVA.Results:Compared with PBS,the PP,SP,PA,SA and CHX showed the antibacterial effect on free S.mutans (P<0.05 );SP and PP showed stronger antibacterial effect than PA,SA and CHX (P<0.05).CHX,SP and PP presented inhibition zones,while PBS,SA and PA did not.Compared with PBS,the CHX,SP and PP could lower the ratio of the live to dead bacteria significantly (P<0.05).Cured self-etching adhesive systems did not show any antibacterial effect on the free S.mutans.Conclusion:The primer of self-etching adhesives ClearfilTM SE Bond and ClearfilTM Pro-tect Bond showed significant antibacterial effect on free and attached S.mutans.The adhesive only showed antibacterial effect on free S.mutans before light-cured polymerization.After being cured,the self-etching adhesive systems did not show antibacterial effect anymore.

Effect of base layer thickness of a self-adhesive resin on dentin bonding strength / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of base layer thickness of DyadFlow(DF) self-adhesive resin on dentin bonding strength.</p><p><b>METHODS</b>Twenty extracted intact human molars were randomly selected and the occlusal surface of each molar was prepared by removing the enamel and exposing the dentin surface. The prepared molars were divided, randomly and equally, into 4 groups. For groups G0.5, G1.0 and G2.0, DF was applied directly on the dentin surfaces following the manufacturer's instruction, and for group GOB, OptiBond All-in-One(OB) self etching adhesive was applied on the dentin surface before using DF. The base layer thickness of DF was 0.5 mm, 1.0 mm, 2.0 mm, 2.0 mm for groups G0.5, G1.0, G2.0 and GOB, respectively. Composite crown were built up on each tooth, then the samples were sectioned longitudinally into sticks with proximately 1.0 mm2 bonding area(for microtensile bond strength[MTBS] testing) or slabs (for bonding interface observation with SEM). Fifteen sticks were obtained for each group. The fracture surface was also observed using SEM and the fracture type of each specimen was determined.</p><p><b>RESULTS</b>The MTBS were: GOB (20.19±3.11) MPa>G0.5 (8.65±1.58) MPa>G1.0 (6.65±1.13) MPa>G2.0 (5.70±0.60) MPa(P<0.05). Bonding interface fracture B2 was most frequently observed for all groups: G0.5: 14/15, G1.0: 13/15, G2.0: 14/15 and GOB: 13/15.</p><p><b>CONCLUSIONS</b>The MTBS decreased when the base layer thickness of DF increased. Direct application of DF self-adhesive resin on dentin surface adhesive restorations should be concerned.</p>

A research on bond strength and interface of dentin adhesives / 实用口腔医学杂志

Objective: To evaluate bond strength and interface of various dentin adhesives by a modified interface processing method. Methods:Nine extracted human molars were ground to expose fresh dentin surface. Three dentin adhesives (Single Bond, Clearfil SE Bond and Clearfil S3 Bond) were applied respectively and a block of composite resin was built up. The specimens were then stored in distilled water for 24 h at 37 ℃ and sectioned into beams of 0.9 mm×0.9 mm cross-sectional area. The microtensile bond strength was determined with Microtensile Tester(n=15). In addition, the bonding specimens were conditioned with 6 mol/L HCl, 5% NaOCl and 0.08 mg/ml hyaluronidase to observe the adhesive interfaces by SEM. Results: Significant differences in bond strength were observed among the three adhesives(P<0.05): SE Bond (45.06±5.29) MPa> Single Bond (35.50±6.40) MPa> S3 Bond (30.46±3.82) MPa. Single Bond showed resin tags about 9-12 μm long and gaps between hybrid and adhesive layers. No obvious boundary between hybrid layer and adhesive were observed for both SE Bond and S3 Bond, while the length of resin tags were 9-14 μm and 4-7 μm for SE Bond and S3 Bond respectively. Conclusion:The morphology of the bond interface of dentin adhesive has a relationship with the bond strength.