Comparative evaluation of self-adhering flowable and conventional flowable composites using different adhesive systems

Introduction: The ability to seal margins is considered as one of the best predictors for the long-term success of bonded restorations. The aim of this study was to compare microleakage in occlusal and gingival margins between cavities filled with self-adhesive flowable and conventional flowable composites using dye penetration. Composite restorations were bonded with self-etch, total etch and universal adhesives. Materials & Methods: In this in vitro study, 32 extracted human premolars for orthodontic purpose were included. Class V cavities(3x3x1.5mm)were prepared on the facial and lingual surfaces of each tooth. The teeth were randomly divided into four equal groups based on the type of material: Single Bond 2 (3M ESPE), Clearfil SE Bond (Kuraray, Tokyo, Japan), Universal Scotch Bond (3M ESPE), and Vertise Flow (Kerr Corp). Bonding agents were applied according to the manufacturer instructions. Then, the cavities of the first three groups were restored with Filtek Flow (3M ESPE, USA). In addition, the teeth were thermocycled for 30 seconds and 1000 cycles at 5°-55°C. Microleakage was evaluated using a stereomicroscope(x40) .Specimens were subjected to a dye leakage test. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests. Results: Significant difference was observed in microleakage among four groups in both occlusal and gingival levels (p≤0.05). No significant difference was found regarding microleakage between Vertise Flow, and Etch - and - rinse and Universal groups. Conclusion: Vertise Flow is a useful material with adequate marginal seal

Effect of expiration date of universal adhesives on the alterations of microtensile bond strength of composite resin to dentin

Introduction: One of the factors affecting the success of bonded restoration is the use of appropriate adhesives and attention to their maintenance time. The aim of this study was to investigate the effect of three time periods related to the expiration date of two universal adhesives on the bond strength of resin composite to dentin. Materials & Methods: In this in-vitro study, 30 intact third human molars were selected. The roots of the teeth were cut and the crown part was mounted in acrylic resin in such a way that the enamel of the buccal surface was clearly visible. Using abrasive disks, the enamel of the buccal surface of the teeth was abraded to create a flat dentin area with dimensions of 25 mm2. The samples were randomly divided into 2 groups based on adhesive type (All Bond (Bisco, Fchaumburg,IL, USA) G-Permio and each group was divided into 3 subgroups based on expiration date. After the bonding process and fabrication of composite samples, microtensile bond strength (TBS) was measured at a speed of 1 mm/min. The data were analyzed using the Kruskal-Wallis test and post hoc Tukey's test. P<0.05 was considered as significant level. Results: Significant differences were found among samples with different expiration dates in both All-Bond Universal (p=0.0001) and G-Premio (p=0.0001) groups in terms of micro TBS (μTBS). In both adhesive groups, a significant difference was found between 2 months after expiration with expiration time and 2 months before expiration, but there was no significant difference between expiration time and 2 months before expiration. Conclusion: The end of the expiration date has a reducing effect on the μTBS of universal adhesives investigated in this study. However, the amount of this effect varies depending on the type of adhesive

The effect of different concentrations of carbamide peroxide on the marginal seal of composite restorations bonded with a self-etch adhesive

Introduction: Bleaching of discolored tooth may affect the tooth/composite interface. The aim of this study was to evaluate the effect of different concentrations of carbamide peroxide (CP) on the marginal seal of composite restorations bonded with a self-etch adhesive. Materials &Methods: In this experimental study Class V cavities were prepared on the buccal and lingual surfaces of 24 intact extracted human molar teeth with gingival margins in dentin and occlusal margins in enamel. The cavities were restored using the adhesive system Clearfil SE Bond and the composite Filtek Z250. Finally, they were randomly divided into four groups (1 control and 3 bleached groups). The control group was kept for two weeks in distilled water at 37° C. The bleached groups were bleached with 10%, 22% and 35% CP gel for 8 hours a day for 14 days. After that, the samples were immersed in 0.5% fuchsin solution and sectioned. Then gingival microleakage was graded. Data was analyzed using Kruskal Wallis and Mann Whitney U test (P≤0.05). Results: Microleakage was observed in the gingival wall of all groups. There was a significant difference between the control group and the bleached groups. Microleakage in the 22% bleached group was less than the other concentrations, but this difference was not significant. Conclusion: Bleaching with different concentrations of CP can increase the microleakage of the gingival wall of Composite restorations bonded with clearfil SE Bond self-etch adhesive and does not recommend

Evaluation of wear resistance and fluoride release from glass ionomer covered with nanofilled self-adhesive coat: An in vitro study

Introduction: The resin-modified glass ionomer (RMGI) materials are hybrid materials including conventional glass ionomer and small addition resin. They have the advantages of both, such as adhesion to tooth structure, esthetics and fluoride release. The purpose of this study was to compare the fluoride release and wear resistance of two types of RMGI. Materials & Methods: In this in vitro study, specimens for measuring the fluoride release were made with brass mold from two types of RMGI EQUIA Forte glass ionomer and Fuji II conventional glass ionomer. After incubating the specimens in a plastic vial containing 7 ml of distilled water, the release of fluoride for each specimen was measured on days 1, 7 and 15 using a PH/Ion meter device. For evaluating the wear resistance, 8 specimens were prepared using a brass mold in each group. Then, each specimen was exposed to 5000, 10000, 20000, 40000, 80000 and 120000 cycles in wear simulator. The specimens’ weight was measured by an electronic weight balance before and after each wear cycle. The data were analyzed by SPSS-17 through repeated-measurement ANOVA and independent T-test. Results: Fluoride released from Fuji II glass ionomer was significantly higher in the first 24 hours and on day 7. During the day 15, the differences in fluoride release between the two glass ionomer groups were not statistically significant. (p<0.001). The EQUIA Forte glass ionomer exhibited significantly greater wear resistance in different wear cycles. (p<0.001) Conclusion: Due to its good wear resistance, acceptable fluoride release, ease of clinical use and infection control, the capsular glass ionomer can be a useful material in people at high risk of caries, temporary restoration techniques, pediatric dentistry and root caries

Effect of different curing modes on the Vickers hardness number and curing depth of bulk fill composites

Introduction: The purpose of this study was to compare the Vickers hardness number (VHN) and depth of cure of two types of bulk fill composites in high, low and soft light curing modes. Materials & Methods: In this experimental study, 60 cylindrical samples were fabricated from two types of bulk fill composites (Tetric N-Ceram and X-tra fil) in a Teflon mold with one semi-circular notch. Then, the samples were randomly divided into the following three subgroups based on the curing modes (high, low and soft) and were light-cured. The samples were removed from the molds, and their VHN and depth of cure were measured. Data were analyzed using One-way ANOVA and Tukey’s post hoc test at the significance level of P<0.05. Results: The mean VHN of the X-tra fil composite was significantly higher than that of Tetric N-Ceram composite (P<0.001). The depth of cure of X-tra fil composite was also significantly higher than that of Tetric N-Ceram composite in high and soft curing modes (P<0.001). Conclusion: According to the current results, X-tra fil composite is a convenient material for the restoration of deep cavity in posterior teeth compared with Tetric N-Ceram

Comparative effects of glazing versus polishing on mechanical, optical, and surface properties of zirconia ceramics with different translucencies

Abstract Objectives This study compared the effects of glazing versus polishing on mechanical, optical, and surface properties of zirconia ceramics with different translucencies. Materials and Methods In this in vitro study, 120 bar‐shaped specimens (25 × 4 × 1.2 mm) were fabricated from three different types of zirconia with different translucencies (n = 40, DD Bio ZW, ZX2, and Cube X2). After sintering, each zirconia group was randomly divided into five subgroups of control (glazing), glazing + bur abrasion, glazing + bur abrasion + polishing with EVE Diacera® kit, glazing + bur abrasion + reglazing, and glazing + bur abrasion + polishing with EVE Diacera® kit + reglazing. The specimens underwent surface roughness, hardness, flexural strength, and translucency tests, as well as X‐ray diffraction (XRD) and scanning electron microscopy (SEM) for assessment of surface topography. Data were analyzed by one‐way analysis of variance, Tukey test, and Pearson test (α = .05). Results Flexural strength, surface hardness, and translucency were significantly correlated with zirconia type. ZW zirconia had significantly higher flexural strength and surface hardness and significantly lower translucency than Cube X2 and ZX2 (p < .001). Surface roughness had no significant correlation with zirconia type (p = .274). Polishing created the smoothest, and bur abrasion created the roughest surface (p < .001). Flexural strength and hardness in most experimental groups were significantly lower than in the control group (p < .001). Translucency was not significantly different in bur abrasion and polishing groups, compared with the control group; however, reglazing significantly increased the translucency (p < .001). SEM micrographs confirmed the surface roughness results. XRD showed monoclinic phase only in reglazed groups. Conclusion Of different surface treatments, polishing improved the surface properties and caused the smallest change in mechanical properties of zirconia with different translucencies

Effect of Fluoride, Casein Phosphopeptide–Amorphous Calcium Phosphate and Casein Phosphopeptide–Amorphous Calcium Phosphate Fluoride on Enamel Surface Microhardness After Microabrasion: An In Vitro Study

Objectives: This study aimed to assess the effect of applying casein phosphopeptide–amorphous calcium phosphate (CPP-ACP) paste, casein phosphopeptide–amorphous calcium phosphate fluoride (CPP-ACPF) paste and sodium fluoride gel on surface microhardness of enamel after microabrasion. Materials and Methods: Thirty freshly extracted human premolars were selected. All samples were subjected to hardness indentations made with the Vickers hardness machine and the average value was recorded as the initial surface microhardness. The specimens were then randomly divided into three groups (n=10) of CPP-ACPF, fluoride and CPP-ACP. The teeth were micro-abraded with Opalustre. Microhardness test was performed to assess the post-abrasion hardness. Three remineralization modalities were performed on samples of each group. The enamel surface microhardness measurements were performed. To compare the difference between groups, the rehardening and softening values were defined. One-way ANOVA and Tukey’s post hoc test at a significance level of 5% were used for statistical analysis. Results: The mean microhardness value (MMV) had a significant decrease after microabrasion from baseline. The MMV had a significant increase after remineralization in all groups. The MMV of CPP-ACPF group was significantly more than that of fluoride group (P=0.027). The rehardening value of fluoride group was significantly more than that of other groups (P<0.001). Conclusion: All the remineralizing agents were effective for rehardening the enamel after microabrasion. The CPP-ACP and CPP-ACPF pastes are effective, but to a lesser extent than neutral sodium fluoride gel in remineralizing enamel surface. Incorporation of fluoride to CPP-ACP formulation does not provide any additional remineralizing potential. Keywords: Casein phosphopeptide-amorphous calcium phosphate nanocomplex; Enamel Microabrasion; Hardness; Sodium Fluorid

Shear Bond Strength of a Resin Cement to Different Alloys Subjected to Various Surface Treatments

Objectives: Micromechanical retention of resin cements to alloys is an important factor affecting the longevity of metal base restorations. This study aimed to compare the bond strength and etching pattern of a newly introduced experimental etchant gel namely Nano Met Etch with those of conventional surface treatment techniques for nickel-chrome (Ni-Cr) and high noble alloys.  Materials and Methods: A total of 120 discs (8×10×15 mm) were cast with Ni-Cr (n=20), high noble BegoStar (n=50) and gold coin alloys (n=50). Their Surfaces were ground with abrasive papers. Ni-Cr specimens received sandblasting and etching. High noble alloy specimens (begoStar and gold coin) received sandblasting, sandblasting-alloy primer, etching, etch-alloy primer and alloy primer alone. Cylindrical specimens of Panavia were bonded to surfaces using Tygon tubes. Specimens were subjected to micro-shear bond strength testing after storing at 37°C for 24 hours. Results: In gold coin group, the highest bond strength was achieved after sandblasting (25.82±1.37MPa, P<0.001) and etching+alloy primer (26.60 ± 5.47 MPa, P<0.01). The lowest bond strength belonged to sandblasting+alloy primer (17.79±2.96MPa, P<0.01). In BegoStar group, the highest bond strength was obtained in the sandblasted group (38.40±3.29MPa, P<0.001) while the lowest bond strength was detected in the sandblast+ alloy primer group (15.38±2.92MPa, P<0.001). For the Ni-Cr alloy, bond strength in the etched group (20.79±2.01MPa) was higher than that in the sandblasted group (18.25±1.82MPa) (P<0.01). Conclusions: For the Ni-Cr alloy, etching was more efficient than sandblasting but for the high noble alloys, higher Au content increased the efficacy of etching

Efficacy of quercetin flavonoid in recovering the postbleaching bond strength of orthodontic brackets: A preliminary study

Objectives: To evaluate comparatively the effect of quercetin on postbleaching shear bond strength (SBS) and adhesive remnant index (ARI). Materials and Methods: Intact maxillary premolars were divided randomly into 12 groups of 10 each: (1) bonding the bracket immediately after bleaching, (2) bonding 1 week after bleaching, (3-8) application of three experimental concentrations of quercetin (0.1%, 0.5%, and 1%) at two time durations (5 and 10 min), (9-10) application of the solvent of quercetin at two time periods (5 and 10 min), (11) application of 10% sodium ascorbate for 10 min, and (12) bonding the brackets on nonbleached teeth. Bleaching was performed using 15% carbamide peroxide gel for 5 days (6 h daily). After incubation and thermocycling, the SBS of brackets was measured. The ARI too was recorded at ×20. The data were analyzed statistically (α =0.05). Results : Bleaching reduced the SBS below 10 Megapascal (MPa) level (P 0.01). All eight postbleaching treatments had rather similar efficacies (P = 0.1396). The concentration of quercetin (beta = 0.259, P = 0.042) but not its duration (beta = 0.213, P = 0.093) significantly improved its efficacy. Conclusion: Bleaching can weaken the bond strength of orthodontic brackets below acceptable levels. The application of quercetin or Vitamin C or delaying the bracket bonding improved the postbleaching SBS