Objectives; This study aimed to evaluate the effect of different surface treatment modalities on surface roughness(SR) and shear bond strength (SBS) of orthodontic molar tubes to lithium disilicate (IPS e-max CAD/CAM, Ivoclar Vivadent) ceramic and human enamel using different adhesives. Materials and methods:A total of 150 e-max specimens were randomly divided into five groups (n=30) according to the method of surface treatment used. In group I (control group): no surface treatment, group II: sandblasting with 50 μm Al 2 O 3 slurry particles, group III: etching with hydrofluoric acid 9.6%, group IV: etching with hydrofluoric acid 4.5% and group V: etching with phosphoric acid 37%. Further random distribution of e-max specimens into subgroups was performed according to the type of adhesive used (One coat 7, G-Premio Bond and Ortho solo). The surface roughness was investigated using digital profilometer and atomic force microscopy (AFM). Microstructural analysis was conducted using scanning electron microscope (SEM).The SBS was measured using universal testing machine. Results were statistically analyzed.Results: Results showed that the sandblasting group had significantly highest surface roughness, while the lowest value was recorded in the Phosphoric acid 37% group. Furthermore, sandblasted group showed the highest SBS, while control group showed the lowest SBS. Strong positive correlation was found between the surface roughness of lithium disilicate and shear bond strength. Meanwhile, no significant differences were found between different adhesive agents use.Conclusions: Shear bond strength was highly affected by the surface roughness which subsequently controlled by the surface treatment modalities and not by the adhesives types. Hydrofluoric acid 4.5% and phosphoric acid 37% are recommended techniques for reliable bond strength between metal tubes and lithium disilicate ceramic.

Purpose: This study was designed to investigate the remineralizing potential of some natural materials (Honey, Whey extract, Zamzam water) versus synthetic product (fluoride tooth paste) on demineralized enamel. Materials and methods: A total of 40 premolars were extracted from 11-14 years old patients. Teeth were washed with distilled water to remove debris; and stored in distilled water contain 0.1% mg thymol.Forty samples were sectioned into two parts (buccal and lingual) then divided into four main groups (20 each) according to materials used; A1: Ginger & honey, A2:Whey extract, A3:Zamzam water & ginger and A4:Fluoride tooth paste. The four groups were further subdivided into two subgroups according to the time of assessment; B1: after 20 days and B2: after 40 days. All samples were treated by demineralizing solution Coca-Cola for 8 minutes, then the samples were mounted and tested materials were applied. Samples were examined with polarized light microscopy. Results: After 20 days, the results revealed that the highest mean value of microhardness was recorded for ginger& zamzam water (273.39), followed by whey extract (256.63), followed by Ginger & honey groups (249.20) while Fluoride group showed the lowest mean of microhardness (219.56). This difference was statistically significant. After 40 days, the results revealed that the highest mean value of microhardness was recorded for Ginger & Zamzam water (266.89), followed by Ginger & honey (260.39), followed by Whey extract group (251.16) while Fluoride group showed the lowest mean of microhardness (226.44). This difference was statistically significant. Conclusion: Natural materials have remineralizing effect on enamel of tooth.

Statement of the problem: Ceramics and glass-ceramics are materials of choice for dental crowns due to their attractive hardness, biocompatibility, etc. However, a major problem with their usage is the observed high wear of either the opposing dental enamel or both the enamel and ceramic itself. Objective: The present study aimed at ranking and comparing the wear performance of three different ceramic systems as an indication of wear. In addition, change in surface roughness was calculated using optical surface profiler. Results: The statistically significant highest mean material's weight loss was recorded in porcelain group, whereas the statistically significant lowest mean weight loss was recorded in BruxZir group. The statistically significant greatest mean antagonist weight loss was recorded for e.max antagonist cusp, whereas the statistically significant lowest mean weight loss was recorded for BruxZir antagonist cusp.Surface roughness increased after wear procedure in all samples. Conclusions: Within the limitations of this in vitro study, monolithic zirconia and porcelain resulted in less wear depth to human enamel compared to lithium disilicate based ceramics (e.max CAD). However, porcelain is more affected by wear compared to zirconia.

Purpose: was to evaluate and compare fracture resistance of some contemporary glass ionomer restorations (Amalgomer CR, EQUIA Fort fil and EQUIA fil) in class II cavities at different time intervals. Materials and Methods: A total of 90 class II cavities were prepared in extracted maxillary premolars (n=90). The samples were divided into three main groups (30 each) according to the materials; These three groups were further subdivided into three groups according to assessment time; 24 hours, one month and three months. Each material was applied to the cavity according to manufactures' instructions. Samples were stored in artificial saliva for the study storage periods. At the end of each storage period samples were subjected to thermocycling at 5˚C and 55˚C for 1000 cycles. The samples were subjected to fracture resistance test using universal testing machine. Failure modes were evaluated using stereomicroscope and micromorphology of fractured restorations and tooth restoration interface were evaluated using Scanning Electron Microscope (ESM). results: the results revealed that the highest mean value recorded for Amalgomer CR followed by Equia Fort fil while Equia fil recorded the lowest mean value. Also the results revealed that the highest mean value recorded after three months storage followed by one moth storage while one month storage recorded the lowest mean value. Conclusions: Fracture resistance of cone temporary glass ionomers in class II cavities is affected by storage for 3 months. Ceramic reinforced glass ionomer (Amalgomer CR) appears promising regarding fracture resistance. IntroduCtIonGlass ionomers were invented in 1969 and reported by Wilson and Kent in the early 1970s in response to the need for a bland, adhesive filling material. It is the product of acid base reaction between an

Objective: The aim of this study was to evaluate the remineralizing effect of Poly (amido amine) dendrimer, Gluteraldehyde and their combination on demineralized dentin at different time intervals. M ate rials and Methods: A total of one hundred and twenty dentin discs were prepared from extracted teeth (n=120), each dentin sample was immersed in 10% citric acid solution for 30 seconds. The samples were divided into two main groups (60 each) according to the assessment time, one week assessment, and four weeks assessment, These two groups were further subdivided into three groups according to the treatment materials; group (1), (n==10): pure G3.0 PAMAM dendrimer, group (II), (n=10): Gluteraldehyde was applied to the demineralized dentin, Group (III), (n=10): a combination of PAMAM dendrimer and Gluteraldehyde. Each group has its control group (n=10) which didn"t receive any treatment. Each treated group with its corresponding control one was placed in a separate container of artificial saliva for one and four weeks. The samples were subjected to microhardness test and Scanning Electron Microscope (SEM). Resu Its: after one week assessment, the results revealed that the highest mean value recorded for PAMAM group (10.9%) followed by PAMAM Gluteraldehyde group (8.3%) while Gluteraldehyde group recorded the lowest mean value (5.26%). This difference was statistically insignificant. After four weeks assessment, the results revealed that the highest mean value recorded for PAMAM-Gluteraldehyde group (14.77%) followed by PAMAM group (14.34%) while Gluteraldehyde group recorded the lowest mean value (8%). This difference was statistically insignificant Conclusions: All treatment materials used were effective in increasing dentin microhardness and produced micromorphological changes of the dentin surface in terms of occluding the orificies of dentinal tubules to variable degree.