Effect of Toothpaste Fluoride Concentration on Color Stability of Resin Composites: An In Vitro Study

Objective: To investigate the effects of two different dentifrice fluoride concentrations on the color stability of the composite. Material and Methods: Twenty-seven specimens (2×4×5 mm) each of microfilled (Gradia, GC, Japan) and nanohybrid (Grandio, VOCO, Germany) composites were prepared. The specimens were randomly divided into six groups (control, Fluoflor caries protection toothpaste with 1450ppm Fluoride (EXW, France), and Fluoflor kids toothpaste with 500ppm Fluoride (EXW, France) (n = 9). The specimens were immersed in a mixture of artificial saliva and toothpaste in a ratio of 1:3 and applied for 60 seconds every 12 hours for 42 days. The control samples were incubated in artificial saliva at 37°C. Primary and secondary color measurements were performed using color parameters (L∗a∗b) with a spectrophotoshade (MHT Optic Research AG, Niederhasli, Switzerland). Data were analyzed using a two-way analysis of variance at a significance level of 0.05. Results: According to the two-way ANOVA analysis, there was no significant difference in color change between the composites and no difference in the level of discoloration between different fluoride concentrations(p>0.05). Also, None of the dentifrices caused clinically significant color changes (ΔE˂3.3). Conclusion: No clinically unacceptable color changes were observed in the microfilled and nanofilled composites with different concentrations of fluoride toothpaste

Effect of Air Abrasion and Erbium-Doped Yttrium Aluminum Garnet (Er: YAG) laser preparation on Shear Bond Strength of Composite to Dentin

Introduction: The aim of this study was to assess shear bond strength of composite to dentin after air abrasion and laser treatment.Methods: 40 human extracted molars divided into 4 groups (n=10) received the following treatments. Group 1: carbide bur, Group 2: air abrasion with aluminum oxide 50 μm, Group 3: irradiated with Erbium-Doped Yttrium Aluminum Garnet (Er: YAG) laser (150 mJ/20Hz), Group 4: irradiated with Er:YAG laser (150 mJ/20Hz)+ air. Specimens in all groups were chemically etched with phosphoric acid 37% and treated with bonding agent (single bond 3M). Then, composite build-up was performed by tygon tube. After storage in distilled water at 37°c for one week, all specimens were subjected to a shear bond strength test with universal testing machine. Data were analyzed with ANOVA and T-Test.Results: The mean and standard deviation of shear bond strength of the 4 groups were 20.8±6.76, 14.98±3.98, 11.43±4.36 and 14.95± 3.18 MPa, respectively.Conclusion: Air abrasion after laser treatment improved the shear bond strength

Effect of addition of Nano hydroxyapatite particles on wear of resin modified glass ionomer by tooth brushing simulation

Recently, incorporation of nanohydroxyapatite (NHA) has been suggested to improve the mechanical properties of glass ionomers (GIs). This study aimed to assess the effect of addition of NHA on wear of resin modified glass ionomer (RMGI) by tooth brushing simulation. In this in vitro, experimental study, NHA in 1, 2, 5, 7 and 10wt% concentrations was added to Fuji II LC RMGI powder, and 48 samples (5×5mm) in five experimental and one control group (n=8) were fabricated. After polishing, cleaning and incubation at 37°C for three weeks, the samples were weighed and subjected to tooth brushing simulation in a toothpaste slurry according to ISO14569-1. Then, they were weighed again and the weight loss was calculated. The data were analyzed using one-way ANOVA and Tukey?s test. The highest and the lowest weight loss was found in the 0% NHA (-1.052±0.176) and 5% NHA (-0.370±0.143) groups, respectively. Wear was significantly higher in 0% NHA group (P<0.05). No difference was detected in wear between 2 and 5wt% NHA or among 1, 7 and 10wt% NHA groups. Significant differences were noted in wear between 2 and 5wt% NHA and 1, 7 and 10wt% NHA groups (P<0.001). Incorporation of up to 10wt% of NHA increases the wear resistance of Fuji II LC RMGI. This increase was the highest when 2 and 5wt% NHA were added

In Vitro Effect of Bleaching With 810 nm and 980 nm Diode Laser on Microhardness of Self-cure and Light-Cure Glass Ionomer Cements

Introduction: This study sought to assess the effect of bleaching combined with irradiation of 810 nm and 980 nm diode laser on microhardness of 2 commonly used self-cure and light-cure glass ionomer cements (GICs) in comparison with conventional bleaching (without laser). Methods: In this in vitro, experimental study, 60 samples were fabricated of A2 shade of Fuji IX and Fuji II LC GICs (n = 30) and each group was divided into 3 subgroups (n = 10). The first subgroups were subjected to bleaching with Opalescence Xtra Boost plus 980 nm diode laser irradiation. The second subgroups were subjected to bleaching with Opalescence Boost plus 810 nm diode laser irradiation and the third subgroups were subjected to bleaching with Opalescence Xtra Boost without laser. Microhardness was measured at baseline and after the intervention using Vickers hardness tester. The data were analyzed using two-way analysis of variance (ANOVA) (P &lt; 0.05).Results: Microhardness decreased in all subgroups after the intervention (P &lt; 0.001) irrespective of the type of GIC (P = 0.201) or surface treatment (P = 0.570). The baseline microhardness of the three subgroups within each group of GIC was not significantly different (P = 0.456), but the baseline microhardness of conventional GIC was significantly higher than that of resin modified GIC (P = 0.004).Conclusion: Bleaching with/without laser irradiation decreases the microhardness of GICs. The baseline microhardness of conventional GIC is higher than that of resin modified GIC

Cytotoxicity Comparison of a Calcium Silicate-Based Resin Cement versus Conventional Self-Adhesive Resin Cement and a Resin-Modified Glass Ionomer: Cell Viability Analysis

Objective:&nbsp;To compare the cytotoxicity level of a new calcium silicate-based resin cement (TheraCem) with two commonly used cements, including a conventional self-adhesive resin cement (Panavia SA) and a resin-modified glass ionomer cement (FujiCem2), on the human gingival fibroblast cells after 24 and 48 hours.&nbsp;Material and Methods:&nbsp;Twelve discs of each cement type were fabricated. The extract of cement disks was made by incubating them in the cell medium. Human gingival fibroblast cells were cultured and exposed to cement extracts for 24 h and 48 h. MTT assay was performed on extracts and optical density and cell viability rates were calculated by the spectrophotometer device at 570 nm. Data were analyzed using ANOVA and Tukey HSD tests.&nbsp;Results:&nbsp;The cell viability rates after 24 hours and 48 hours were as follows: TheraCem: 89.24% and 85.46%, Panavia SA: 49.51% and 46.57% and FujiCem2: 50.63% and 47.36%. TheraCem represented the highest cell viability rate. However, no significant difference was noted between Panavia SA and FujiCem2. Time had no significant effect on cell viability.&nbsp;Conclusion:&nbsp;TheraCem exhibited the best results among three tested cements and was considered non-toxic. Panavia SA and FujiCem2 were not significantly different regarding the cell viability rate. Time had no significant effect on the cytotoxicity level of cements

Amalgam Surface Treatment by Different Output Powers of Er:YAG Laser:SEM Evaluation

Introduction: The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM).Methods: Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM.Results: The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularitiesConclusion: It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets

Vickers micro-hardness study of the effect of fluoride mouthwash on two types of CAD/CAM ceramic materials erosion

The aim of this study was to evaluate the protective effects of fluoride mouthwash on the surface micro-hardness of two types of CAD/CAM ceramics after exposure to acidic solutions. Methods 40 samples (5 × 5 × 3 mm3) were prepared from two different ceramics: Vitabloc Mark II CAD, and IPS e.max CAD. The samples were randomly divided into 5 groups in each ceramic (n = 8) immersed in different solutions: Gs: saliva: GGA: gastric acid, GAA: acetic acid, GFGA: sodium fluoride + gastric acid, GFAA: sodium fluoride + acetic acid. The microhardness of samples was measured before and after immersion in different solutions by Vickers microhardness tester. By subtracting the microhardness values after and before immersion, the microhardness changes of the samples were obtained. Data were analyzed by Two-way analysis of variance, one-way analysis of variance, and Tukey test (α = 0.05). Results Immersion in different solutions reduced the microhardness. Microhardness loss was significantly affected in G FAA and G FGA groups in both types of ceramics (P < 0.05). For Vitabloc Mark II groups, the microhardness loss was significantly higher in GFAA and GFGA compared to IPS e.max CAD P < 0.001). Conclusion Fluoride mouthwash in conjunction with acidic solutions may adversely affect microhardness of Vitabloc Mark II CAD, and IPS e.max CAD that may consequently compromise the clinical service. Vitabloc Mark II CAD was significantly more affected than IPS e.max CAD

Bond Strength of Fiber Posts to Composite Core: Effect of Surface Treatment With Er,Cr:YSGG Laser and Thermocycling

Introduction: This study aimed to determine the bond strength of fiber post to composite core following surface treatment with Er,Cr:YSGG laser at different powers and sandblasting with and without thermocycling.Methods: In this experimental study, 30 fiber posts (Glassix, Nordin, Switzerland) were randomly divided into 5 groups of sandblasting, no treatment and laser irradiation at 1, 1.5 and 2 W powers. Following composite filling and mounting, 1-mm thick sections were made for push-out bond strength testing. Half of the samples in each group were subjected to thermocycling (n=15). Two-way analysis of variance (ANOVA) was used to analyze the bond strength values. Pairwise comparisons were made using Tukey test (P &lt; 0.05).Results: Effect of treatment method on push-out bond strength of fiber post to composite core was significant (P = 0.017), while thermocycling had no significant effect on bond strength (P = 0.964). Pairwise comparison of surface treatment methods revealed no significant difference in groups with and without thermocycling (P &gt; 0.05), but Er,Cr:YSGG laser irradiation with 1 W power yielded significantly higher bond strength than the control group (P =0.01).Conclusion: Irradiation of Er,Cr:YSGG laser at 1 W power increased the bond strength of fiber post to composite core. Thermocycling slightly decreased the bond strength at the fiber post-core interface

Effect of Intracanal Post Space Treatments on Push-Out Bond Strength of Fiber Posts to Root Dentin

Objectives: The main disadvantage of fiber posts is their low bond strength to root canal wall. The aim of the present study was to assess the effect of different root canal post space treatments on push-out bond strength of fiber posts to root dentin. Materials and Methods: After post space preparation in 40 endodontically treated human premolars, the teeth were randomly divided into four experimental groups: Group 1: control group, group 2: Endsolv R, group 3: ultrasonic cleaning, group 4: Clearfil Repair. Afterwards, the posts were bonded with Panavia F 2.0 bonding cement. The bond strength of fiber posts to root canal wall in the middle part of canal was evaluated following thermocycling using push-out test. Data were analyzed using one-way ANOVA and Tamhane’s multiple comparisons test. The failure mode of each group was determined under a stereomicroscope. Results: There was a significant difference in the mean push-out bond strength among the groups (P0.05). Conclusions: It seems that ultrasonic cleaning and Clearfil Repair can modify the root canal wall and significantly increase the bond strength of fiber posts.