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Purpose: To evaluate the effect of pomegranate and banana extracts (natural antioxidants) versus ascorbic acid (synthetic antioxidant) prepared in 10% and 15% concentrations on microshear bond strength (µSBS) to bleached enamel. Materials and Methods: A total of 56 bovine incisors were selected for the current study. Forty teeth were used for microshear bond strength and divided into 5 groups according to antioxidant type; Group 1: No bleaching + No antioxidant (negative control), Group 2: Bleaching + No antioxidant (positive control), Group 3: ascorbic acid, Group 4: pomegranate extract and Group 5: banana extract. Groups 3,4 and 5 were further divided into 2 subgroups according to concentration of antioxidant: 10% and 15%.Bleaching gel was applied according to manufacturer instructions. Antioxidants were applied for 10 min. Composite specimens were prepared and tested for µSBS using universal testing machine. Sixteen bovine incisors were prepared and tooth-restoration interfaces were assessed using SEM. Data were tabulated and statistically analyzed.Results: Negative control and 15% ascorbic acid recorded the highest mean µSBS values followed by 15% and 10% pomegranate groups. No significant difference was reported between 10% ascorbic acid and 15% banana. Lowest mean values were obtained with 10% banana and positive control groups with no significant difference between them. Conclusions: Pomegranate in both concentrations and 15% banana extract could partially reverse compromised bond strength. Use of 15% ascorbic is able to totally regain bond strength to bleached enamel. Banana extract in low concentration is not beneficial in improvement of bond strength after bleaching.

Objective: This research was conducted to investigate the effect of chemical challenge on the compressive strength (CS) and surface roughness (Ra) of a ceramic reinforced glass ionomer in comparison to a nanofilled resin composite.Methods: A total of 60 disc specimens (6mm height x 4mm diameter) were prepared for the compressive strength testing and another 60 disc specimens (5mm diameter x 2mm thickness) for the surface roughness testing. Specimens were divided into 2 groups (n=30) according to the material used; ceramic reinforced glass ionomer (Amalgomer CR, Advanced Health Care Ltd, Tonbridge, Kent, UK) and nanofilled resin composite (Filtek TM Z350 XT, 3M ESPE, St.Paul, MN,USA). Each group was divided into 3 subgroups (n=10) according to the storage media; distilled water (control), 0.02N citric acid and 50% ethanol. Specimens were stored for 7 days at 37ºC. After storage period, they were subjected to compressive loading using a universal testing machine and surface roughness testing using white light interferometer. Data were tabulated and statistically analyzed using Two-way ANOVA followed by Bonferroni's post-hoc test.Results: Amalgomer CR recorded a significantly lower CS and higher Ra than nanofilled resin composite under different storage media. Citric acid revealed the lowest CS of Amalgomer CR followed by ethanol in comparison to distilled water with significant difference between them. For nanofilled resin composite, both citric acid and ethanol significantly decreased CS. Ethanol showed the highest Ra values for both restorative materials. Conclusions:The performance of Amalgomer CR under different storage media was inferior to nanofilled resin composite regarding compressive strength and surface roughness. Citric acid severely affected compressive strength of Amalgomer CR. Nanofilled resin composite was able to preserve its surface roughness within the clinically acceptable threshold after chemical challenge in contrary to Amalgomer CR.

Objective: The current study was conducted to investigate the effect of essential oil (EO) modification of glass ionomer cement (GIC) on antibacterial activity and compressive strength.Methods: A total of 100 specimens were prepared; 50 specimens for the antibacterial activity test (3 mm x 2 mm) and 50 specimens for the compressive strength test (4 mm x 6 mm). Specimens were divided into five groups (n=10) according to the type of the essential oil used in modification of GIC; Group 1: unmodified glass ionomer cement (control group); Group 2: 2.5% bergamot modified GIC; Group 3: 2.5% peppermint modified GIC Group 4: 2.5% lemongrass modified GIC and Group 5: 2.5 % fennel modified GIC. Antibacterial activity was assessed using agar diffusion test. Compressive strength test was performed using universal testing machine. Data were tabulated and statistically analyzed.Results: Bergamot modified GIC recorded the highest mean inhibition zone, followed by fennel, then lemongrass and peppermint. The lowest mean value was revealed by the control group. Regarding compressive strength results, control group showed the highest mean value, followed by lemongrass, then peppermint and bergamot. The lowest mean value was recorded by fennel modified GIC. Conclusion:Essential oil modification of GIC was effective in enhancing the antibacterial activity although it adversely affects compressive strength in comparison to the control group. Lemongrass and peppermint essential oil modification of GIC were effective in improving antibacterial property while preserving an acceptable compressive strength according to the ISO standards.

Objective: to evaluate the effect of peroxide free versus peroxide containing whitening agents on color change and surface roughness of enamel.Methods: A total of 30 bovine incisors were used for the current study. Teeth roots were sectioned and crowns were mounted in self-cured acrylic resin blocks. The teeth were randomly divided into three groups (n= 10) according to the whitening agent used: Group I: Control group (No treatment), Group II: Peroxide free whitening agent (BlanX White Shock toothpaste) and Group III: Peroxide containing whitening agent (White smile bleaching agent). The specimens were stained using black tea solution. BlanX toothpaste was used twice daily for 8 days while white smile bleaching material was applied for 3 sessions, 20 min each. Color change was assessed using VITA Easyshade spectrophotometer and surface roughness (Ra) was measured using a white light interferometer. Data were tabulated and statistically analyzed. Results:Color change results revealed that both whitening agents were able to restore color comparable to the control group with no significant difference between them. Regarding surface roughness, no significant difference was reported between BlanX toothpaste and the control group which showed low surface roughness while white smile bleaching agent recorded the highest surface roughness value. Conclusion:BlanX toothpaste was able to improve tooth color without altering enamel surface roughness. Although, white smile bleaching agent was effective in restoring tooth color, it negatively affects surface roughness.