Background Remineralizing of bleached enamel is a common procedure that aims to compensate enamel mineral lose. This study aimed to evaluate the remineralization effectiveness of experimentally prepared grape seed extract hydrogels (GSE) compared to fluoride gel on bleached enamel. Material and Methods Thirty extracted maxillary incisor were bleached using white smile bleaching agent. Bleached specimens were divided into three groups (10/group) according to the remineralizing agents tested: [GSE 6%, GSE 10%, or fluoride gel]. After bleaching and remineralization procedure, the specimens were stored in artificial saliva at 37°C. Micro-hardness and Energy-Dispersive X-ray and ultra-morphological evaluation were tested at baseline, after bleaching and after remineralization. Results Statistical significant decrease on mean micro-hardness values had resulted after bleaching procedure compared to baseline, followed by a significant increase in GSE (10%) and fluoride groups. GSE (6%) application showed the least statistical significant mean micro-hardness, which was statistically insignificant different compared to bleaching procedure. Elemental analysis results revealed a statistical significant decrease on Ca, and Ca/P ratios (At%) values after bleaching compared to baseline, followed by a significant increase after treatment with all tested remineralizing gels. SEM photomicrograph of sound enamel shows smooth uniform appearance with few pores. Bleached enamel showed irregular pitted disorganized enamel surface. Bleached enamel exposed to GSE and fluoride gel showed occlusion of enamel surface porosities and precipitates of different sizes. Conclusions The specially prepared GSE hydrogels has positive effects on the remineralization process of bleached enamel making it an effective natural agent with remineralizing potential. Key words: Remineralization, bleaching, grape seed extract, fluoride, enamel.

Background To evaluate the bleached enamel shear bond strength (SBS) after antioxidants application using an experimental adhesive. Material and Methods Sixty sound human molars had their roots removed then cut into buccal and lingual halves and mounted in acrylic blocks. Enamel bleaching was done using an in-office chemical bleaching agent. Specimens were arbitrarily allocated into 12 groups (n=10) regarding the three experimental levels of the study: two antioxidant agents [10% açai berry extract, 10% sodium ascorbate prepared gels (applied for 15-min) and the control group (no antioxidant application)], two adhesive materials [commercial etch-and-rinse (ER) adhesive and an experimental ER adhesive] and two post-bleaching SBS testing times [24-h and 2-w]. Specimens were restored with a nano-hybrid resin composite restoration then stored in distilled water at 37◦C till SBS testing. Results Three-way ANOVA showed that the antioxidant agents, adhesive materials and the post-bleaching SBS testing times had a statistically significant effect on the bleached enamel SBS. Açai berry extract groups recorded the highest mean values, while the control groups demonstrated the least values with a statistically significant difference between the antioxidant agents’ groups. Commercial ER adhesive recorded statistically significant higher SBS values than the experimental adhesive and the 2-w post-bleaching SBS testing time demonstrated statistically significant higher SBS values than the 24-h groups. Conclusions Açai berry extract is a powerful antioxidant agent, that has the potential to instantly restore the bleached enamel depleted SBS. The commercial adhesive has successfully restored the depleted SBS of the bleached enamel than the tested experimental adhesive. Key words: Antioxidant application, açai berry extract, etch-and-rinse adhesives, experimental adhesive, shear bond strength.

Background Limited data is available regarding the prevalence of dental caries as a chronic disease among adolescents using different caries assessment indices. The aim of this study was to compare and describe the prevalence of dental caries among group of Egyptian students using two caries assessment indices; DMFS and ICDAS II. Methods This descriptive, cross-sectional epidemiological study included 2760 public secondary school students with age range from 15 to 18 years with permanent dentition and good general health. Presence of; retained teeth, congenital or developmental anomalies in the permanent dentition, orthodontic treatments, systematic conditions, smoking and general health problems were considered the exclusion criteria in this study. Participants were selected randomly from 8 public secondary schools in the Great Cairo, Egypt. The examination was achieved by 6 trained and previously calibrated examiners using sets of diagnostic mirrors, compressed air, a WHO probe and cotton rolls. DMFS index and ICDAS II system were used as caries detection methods. In DMFS index; the number of decayed (D), missing (M) and filled (F) surfaces was recorded, while in the ICDAS II index, the assessment of both cavitated and non-cavitated carious, missed and filled teeth with restorations /sealants was recorded. The examiners performed the oral examination using both scoring systems in an alternating manner. The collected data were explored for normality using Kolmogorov–Smirnov and Shapiro–Wilk tests. Chi square test was used to analyze the frequencies. Results There was a statistical significant difference between the DMFS and ICDAS II methods results regarding the recorded number of caries affected teeth and cavitated teeth surfaces. The prevalence of dental caries among the investigated secondary school students was (69.56%) and (78.29%) for DMFS and ICDAS II, respectively. Conclusions The prevalence of dental caries among Egyptian adolescent is high. ICDAS scoring system revealed higher caries prevalence values than DMFS method. ICDAS method is the best choice for the preventive goals, while DMFS is sufficient for clinical purposes.

Objective To investigate experimental eggshell powder (ESP) solution application effect on shear bond strength (SBS) test timing of bulk-fill resin composite to bleached enamel. Methods Eighty bovine-extracted anterior teeth were alienated to eight groups (n = 10), representing shear bond strength test timing periods (immediate or delayed) and the remineralizing agents investigated (MI paste Plus and ESP solution). Enamel surfaces were bleached using in-office chemical bleaching agent and the two remineralizing agents were applied then self-etch adhesive and bulk-fill resin composite were performed at 24 h and 14 d before SBS test was done. One-way ANOVA followed by Tukey post hoc test was performed for statistical analysis. Results The control groups showed the highest mean values, while the bleached enamel groups recorded the least mean values. ESP bleached enamel group recorded a significantly higher mean SBS values than MI paste Plus bleached group. Delayed SBS groups showed higher mean values than immediate SBS groups except for control group. Conclusions ESP had a positive and significant effect on SBS of bulk-fill resin composite to bleached enamel surface. Delaying the bonding procedure and restoration of the bleached teeth using resin composite restorations results in a better bond durability.