Clinical Relevance The use of resin-modified glass ionomers as cavity liners in the closed-sandwich technique reduced microleakage in Class II composite restorations.

Aim:The aim was to evaluate the antibacterial properties of composite resin containing nanosilver against Streptococcus mutans (SM) and Lactobacillus (L). Materials and methods:Nanosilver was added to Z250 composite at 0.5 and 1% by weight. In order to confirm the homogenous distribution of the nanoparticles in the composite resin, SEM-EDX analysis was performed on one sample in each group. Z250 composite without nanosilver was used as control. Direct contact test was used to test the antibacterial properties of nanoparticle-loaded composites: 0.001 ml of 0.5 Mc Farland suspension of MS and L was placed on composite disks, and incubated for 1 hour in 5 to 10% CO 2 incubator at 37ºC. Samples were placed in 0.5 ml of sterile BHI broth and incubated for 2 hours in CO 2 incubator. Afterwards, 0.001 ml liquid from each medium was distributed on blood agar plates and incubated for 48 hours in CO 2 incubator. The numbers of bacterial colonies were counted visually. Data were analyzed using Two-way ANOVA and Tukey HSD test. Significance level was set at 0.05. Results:Addition of nanosilver to composite resin had a significant effect on reduction of the number of SM and L colonies (p = 0.000). The antibacterial properties of composite resins are different depending on the concentration of nanosilver (p = 0.014). Tukey test indicated that increase in the concentration of nanosilver caused the increase in antibacterial properties of composite resin. Conclusion:Addition of silver nanoparticles to Z250 composite could significantly inhibit the growth of Streptococcus mutans and Lactobacillus on the surface of this composite.Clinical significance: The addition of nanosilver to Z250 composite could inhibit the growth of SM and L on the surface of the restoration and therefore prevent the occurrence of secondary caries.

Incorporation of silver nanoparticles into composite resins is recommended for their reported antibacterial properties, but this incorporation can affect the wettability of such materials. Therefore, this study evaluated the effect of nano-silver addition to silorane-based and methacrylate-based composites on their contact angle. Nano-silver particles were added to Z250 (methacrylate-based) and P90 (silorane-based) composites at 0.5% and 1% by weight. The control group had no additions. SEM-EDX analysis was performed to confirm the homogeneity of the nano-silver distribution. Seventy-two composite discs were prepared and standardized to the identical surface roughness values, and then distributed randomly into 6 groups containing 12 samples each (N = 12). Two random samples from each group were observed by atomic force microscopy. Distilled water contact angle measurements were performed for the wettability measurement. Two-way ANOVA, followed by the Tukey-HSD test, with a significance level of 5%, were used for data analysis. It was observed that wettability was significantly different between the composites (p = 0.0001), and that the addition of nano-silver caused a significant reduction in the contact angle (p = 0.0001). Wettability varied depending on the concentration of the nano silver (p = 0.008). Siloranebased composites have a higher contact angle than methacrylate-based composites. Within the limitations of this study, it can be concluded that the addition of 0.5% nano-silver particles to the composites caused a decrease in the contact angle of water.

APF, TiF and TiF before CO laser irradiation significantly increased the micro-hardness of initially demineralized enamel surfaces. CO laser irradiation before TiF application could not remineralize the white-spot lesions.

Aim:The aim was to evaluate the influence of water storage on fiber post-resin composite adhesion after different postsurface treatments.Materials and Methods:Forty-two fiber posts were used. Half of them were treated by hydrogen-peroxide and the other half were sandblasted. The adhesive (Single Bond, 3M, USA) was applied on the post. Core was built-up using flowable composite (Ælite Flow, Bisco, USA). The specimens were divided into eight groups. Group 1 was treated with H2O2. Groups 2–4 were treated with H2O2 but stored for 3, 6, and 9 months, respectively. Groups 5–8 were sandblasted and stored for 0, 3, 6, and 9 months. μTBS was measured and data analyzed using one-way ANOVA and Tukey HSD. The fractured surfaces were evaluated by a stereomicroscope. The morphology of interfaces was assessed under SEM. H2O2-treated groups showed higher bond-strength.Results:The effect of “surface-treatment method” and “storage-time” was significant (P<0.0001), but there was no significant difference for their interaction effect (P=0.05). Water aging significantly decreased μTBS.Conclusions:Water aging significantly decreased microtensile bond strength regardless of the type of post surface treatment.

Background:Bleaching treatments decrease shear bond strength between orthodontic brackets and teeth; although definite results have not been reported in this regard.Objectives:This study determined the effects of different bleaching protocols on the shear bond strength of orthodontic brackets to teeth.Materials and Methods:This experimental study was performed in Iran. Forty-eight extracted human premolars were randomly assigned into four groups. In the control group, no bleaching treatment was performed. In groups 2 - 4, the bleaching procedures were performed using carbamide peroxide 45%, carbamide peroxide 20% and diode laser, respectively. Two weeks later, brackets were bonded to teeth and thermocycled. The shear bond strengths of the brackets to the teeth were measured. Data was analyzed by one-way ANOVA and Dunnett post-hoc test.Results:Shear bond strength of the brackets to the teeth were 10.54 ± 1.51, 6.37 ± 0.92, 7.67 ± 1.01 and 7.49 ± 1.19 MPa, in groups 1 - 4, respectively. Significant differences were found between control group and all other groups (P < 0.001); and also between groups 2 and 3 (P < 0.05). No significant differences were found between the other groups.Conclusions:The bleaching procedures using 20% carbamide peroxide and 45% carbamide peroxide and diode laser significantly decreased shear bond strength of brackets to the teeth. 45% carbamide peroxide had a more significant effect on bond strength compared to 20% carbamide peroxide. The difference in bond strength was not significant between laser group and either carbamide peroxide groups.

Background:Fiber reinforced composite (FRC) posts are cemented with resin cements. It is reported that using resin cements in canals sealed with eugenol-containing sealers reduces the post retention. However, there is controversy on the subject.Aims:The aim was to investigate the influence of eugenol-containing sealers and the amount of dentin removal from root canal with different post diameters on retention of FRC posts.Settings and Design:It was an in vitro studyMaterials and Methods:The roots of sixty teeth were cut with 14 mm distance from the apex and were instrumented to the working-length of 13 mm. The teeth were randomly distributed into 2 groups (n = 30). Following storage in normal saline for 7 days, the samples in both the groups were further divided into 3 subgroups (n = 10). Canals in the experimental subgroups (I, II, III) were obturated by gutta-percha and eugenol-containing sealer; and in the control subgroups (IV, V, VI) without any sealer. After storage in normal saline for 7 days, the post space was prepared by #3, #2, and #1 drills of DT Light-Post system. Post was cemented with Panavia-F2.0 resin-cement. A composite core was built for each sample. All samples were thermo cycled for 1000 cycles. The samples were tested for post retention with a mechanical testing machine.Statistical Analysis:Data were analyzed by two-way ANOVA and Tukey-HSD test.Results:There was not a significant difference in retention between FRC posts #1 and #2 (P > 0.05). Post #3 was more retentive than posts #1and #2 (P < 0.05). ZOE sealer significantly reduced the retention of posts (P = 0.024), however, increasing post-space diameter significantly increased post retention in canals coated with ZOE sealer (P = 0.002).Conclusions:Eugenol-containing sealer reduced the retention of FRC posts cemented with resin cement. Removing more dentin from root-canals treated with eugenol-containing sealer for placing larger diameter posts caused an increase in post retention.

Background:Attempts to improve bond strength of self-etch adhesives can enhance the durability of composite restorations.Aims:The aim of the present study was to evaluate the effect of collagen and smear layer removal with sodium hypochlorite solution (NaOCl) and EDTA on micro-tensile bond strength (μTBS) of self-etch adhesives to dentin.Settings and Design:It was an in-vitro study.Materials and Methods:Seventy-two teeth were divided into eight groups and their crowns were ground perpendicular to their long axis to expose dentin. The teeth were polished with silicon-carbide papers. The groups were treated as follows: No conditioning, 0.5-M EDTA conditioning, 2.5% NaOCl conditioning, NaOCl + EDTA conditioning. The surfaces were rinsed and blot-dried. Clearfil S3 and I-Bond were applied according to manufacturers’ instructions and restored with Z100 composite. After 500 cycles of thermo-cycling between 5°C and 55°C, the samples were sectioned and tested for μTBS.Statistical Analysis:Data were analyzed by two-way ANOVA and Tukey-HSD test.Results:The highest μTBS was recorded with Clearfil S3 + NaOCl + EDTA, and the lowest was recorded with I-Bond without conditioning. μTBS in EDTA-and EDTA + NaOCl-treated groups was significantly higher than the control and NaOCl-conditioned groups.Conclusions:Application of EDTA or EDTA + NaOCl before one-step self-etch adhesives increased μTBS.