Current materials used for maxillofacial prostheses are far from ideal and there is a need for novel improved materials which mimic as close as possible the natural behavior of facial soft tissues. This study aimed to evaluate the effect of adding different concentrations of surface treated silicon dioxide nanoparticles (SiO2) on clinically important mechanical properties of a maxillofacial silicone elastomer. 147 specimens of the silicone elastomer were prepared and divided into seven groups (n = 21). One control group was prepared without nanoparticles and six study groups with different concentrations of nanoparticles, from 0.5% to 3% by weight. Specimens were tested for tear strength (ASTM D624), tensile strength (ASTM D412), percent elongation, and shore A hardness. SEM was used to assess the dispersion of nano-SiO2 within the elastomer matrix. Data were analyzed by one-way ANOVA and Scheffe test (α = 0.05). Results revealed significant improvement in all mechanical properties tested, as the concentration of the nanoparticles increased. This was supported by the results of the SEM. Hence, it can be concluded that the incorporation of surface treated SiO2 nanoparticles at concentration of 3% enhanced the overall mechanical properties of A-2186 silicone elastomer.

Polyether-ether-ketone (PEEK) biomaterial has been increasingly employed for orthopedic, trauma, spinal, and dental implants due to its biocompatibility and in vivo stability. However, a lack of bioactivity and binding ability to natural bone tissue has significantly limited PEEK for many challenging dental implant applications. In this work, nanocomposites based on PEEK reinforced with bioactive silicate-based bioceramics (forsterite or bioglass) as nanofillers were prepared using high energy ball milling followed by melt blending and compression molding. The influence of nanofillers type and content (10, 20 and 30 wt.%) on the crystalline structure, morphology, surface roughness, hydrophilicity, microhardness, elastic compression modulus, and flexural strength of the nanocomposites was investigated. The scanning electron microscopy images of the nanocomposites with low nanofillers content showed a homogenous surface with uniform dispersion within the PEEK matrix with no agglomerates. All nanocomposites showed an increased surface roughness compared to pristine PEEK. It was found that the incorporation of 20 wt.% forsterite was the most effective in the nanocomposite formulation compared with bioglass-based nanocomposites; it has significantly improved the elastic modulus, flexural strength, and microhardness. In vitro bioactivity evaluation, which used biomimetic simulated body fluid indicated the ability of PEEK nanocomposites loaded with forsterite or bioglass nanofillers to precipitate calcium and phosphate bone minerals on its surface. These nanocomposites are expected to be used in long-term load-bearing implant applications and could be recommended as a promising alternative to titanium and zirconia when used as a dental implant material.

Objectives: This in vitro study aimed to evaluate the gingival microleakage in class II cavities in primary molars restored with a low shrink silorane resin composite (Filtek P90) or a nanohybride composite resin(Filtek supreme XT) using three different techniques, (total bonding, closed or open sandwich techniques)lined by nano-filled resin modified glass ionomer cement RMGIC (Ketac N100). Additionally, the shear punch bond strength between the two types of composite and KN100 was also examined. Study design:For microleakage test, two standardized class II slot cavities were prepared in proximal surfaces of 60 sound extracted primary molars which were divided into 2 groups of 30 each according to the type of composite. Each group was subdivided into 3 groups (n = 10) according to the restorative technique used. The restored teeth were examined for microleakage after immersion in 2% methylene blue dye using stereomicroscope at 20 X. Microleakage scores among the groups were compared using Kruskal Wallis test followed by pair wise Mann Whitney U test at P ≤ 0.05. Thirty disc specimens were prepared for determining the shear punch bond strength between the two composite materials and the KN100. Specimens were divided into 5 groups (n = 6) according to the adhesive protocol. The differences in mean bond strength values in MPa between groups were statistically analyzed using ANOVA followed by pair wise Tukey Post hoc test at P ≤ 0.05.Mode of failure was also evaluated for all groups. Results: Both the silorane resin and nano-composite resin showed superior marginal seal with the total bonding technique compared to closed and open sandwich techniques. The recorded mean shear punch bond strength values showed no statistical significant difference between the two resin composites without or with their adhesive bonding systems when bonded to the nano-ionomer. All specimens showed cohesive mode of failures except for silorane resin with Adper Easy Bond Self Etch Adhesive (AEBSEA) which showed adhesive mode of failure. Conclusions: The best marginal seal was obtained with the total bonding technique using both resin composites. The shear punch bond strength between KN100 and the two composite materials was not affected by either of the used adhesive bonding agent.

Background In recent years, treated dentin matrix (TDM) has been introduced as a bioactive hydrogel for dentin regeneration in DPC. However, no study has introduced TDM as a photocrosslinkable hydrogel with a natural photoinitiating system. Therefore, the present study aimed to explore the synthesis, characterizations and grafting optimization of injectable gelatin- glycidyl methacrylate (GMA)/TDM hydrogels as a novel photocrosslinkable pulp capping agent for dentin regeneration. Methods G-GMA/TDM hydrogel was photocrosslinked using a new two-component photoinitiating system composed of riboflavin as a photoinitiator under visible light and glycine as a first time coinitiator with riboflavin. The grafting reaction conditions of G-GMA/TDM e.g. GMA concentration and reaction time were optimized. The kinetic parameters e.g. grafting efficiency (GE) and grafting percentage (GP%) were calculated to optimize the grafting reaction, while yield (%) was determined to monitor the formation of the hydrogel. Moreover, G-GMA/TDM hydrogels were characterized by swelling ratio, degradation degree, and cytotoxicity. The instrumental characterizations e.g. FTIR, 1H-NMR, SEM and TGA, were investigated for verifying the grafting reaction. Statistical analysis was performed using F test (ANOVA) and Post Hoc Test (P = 0.05). Results The grafting reaction dramatically increased with an increase of both GMA concentration and reaction time. It was realized that the swelling degree and degradation rate of G-GMA/TDM hydrogels were significantly reduced by increasing the GMA concentration and prolonging the reaction time. When compared to the safe low and moderate GMA content hydrogels (0.048, 0.097 M) and shorter reaction times (6, 12, 24 h), G-GMA/TDM with high GMA contents (0.195, 0.391 M) and a prolonged reaction time (48 h) demonstrated cytotoxic effects against cells using the MTT assay. Also, the morphological surface of G-GMA/TDM freeze-dried gels was found more compacted, smooth and uniform due to the grafting process. Significant thermal stability was noticed due to the grafting reaction of G-GMA/TDM throughout the TGA results. Conclusions G-GMA/TDM composite hydrogel formed by the riboflavin/glycine photoinitiating system is a potential bioactive and biocompatible system for in-situ crosslinking the activated-light pulp capping agent for dentin regeneration.

In the last decade, the total number of cellular phone (CP) subscribers in Egypt increased from only 654000 subscribers in October 1999 to 55.352 million in December 2009. Latest available data in February 2012 recorded 112.74 CP subscribers per 100 inhabitants. CPs are composed of a variety of materials containing toxic substances that have bad impacts on both health and environment when disposed of an incorrect manner. On the other hand, environmentally friendly cellular phone waste management system has many benefits. More than 70% of the CP can be recycled, one ton of this recycled waste can generate up to 230 grams of gold. This paper aims to assess the current situation of CP waste in Egypt. Published data were collected from concerned institutions of cellular phones in Egypt as: Ministry of Communication and Information Technology (MCIT), Ministry State of Environmental Affairs (MSEA), as well as regional and international ones as: Basal convention Regional office in Cairo (BCRC),The Center of Environment and Development for the Arab Region and Europe (CEDARE), world Bank (WB) and International Telecommunication Union (ITU).The study revealed that CP waste in Egypt is not well assessed. Few efforts were done to collect specific CP batteries, while efforts to manage other CP waste components were not satisfactory due to absence of facilities and expertise for proper dismantling, recycling and disposal of this precious yet hazardous waste. To conclude, there is a need for assessment of different types of electronic waste (e-waste) in general in Egypt. Establishing governmental and private partnership and a legal framework for e-waste trade in Egypt is recommended. Organizing awareness campaigns about ewaste is also needed.

INTRODUCTION: During the past decade, composites have become the most commonly used restorative materials. The rate of dental caries following treatment with composite resin is high. Therefore, one of the most applicable methods for preventing enamel demineralization around the restorations is using dental materials resistant to the bacterial accumulation OBJECTIVES: To synthesis and characterize antibacterial nanoparticles and to evaluate the effect of blending microhybrid composite with zinc oxide nanoparticles (ZnO), Chitosan (Cs) and combination of both Chitosan/Zinc oxide nanoparticles (Cs/ZnO) and properties of these nanoparticles on the composite resin. MATERIALS AND METHODS: Three antibacterial nanoparticles were prepared and characterized in terms of particle size, zeta potential, shape, morphology and functional group determination. Minimum inhibitory concentration of the nanoparticles was determined. The nanoparticles were incorporated into commercial microhybrid composite resin. The antibacterial properties against Streptococcus mutans were evaluated by disc diffusion test and direct contact test. The results were analyzed using ANOVA test at p ≤ .05 significance level. RESULTS: For agar diffusion disc, incorporation of ZnO nanoparticles into the composite resin results in an antibacterial effect which lasted for up to 12 weeks, while for the Cs and Cs/ZnO nanoparticles the antibacterial effect lasted for up to 2 weeks. The direct contact test visualized under SEM also showed that incorporation of ZnO nanoparticles into composite resin to be the most inhibitory in all the 4 groups, denoting that ZnO-NPs has a far better inhibitory effect than Cs-NPs and Cs/ ZnO-NPs. CONCLUSIONS Antibacterial nanoparticles could be synthesized and characterized by Zetasizer NanoZS, scanning electron, transmission microscopy and Fourier transform infrared spectroscopy. Incorporation of ZnO, Cs and Cs/ZnO nanoparticles into the composite resin could significantly inhibit the S. mutans. The antimicrobial efficacy of the ZnO nanoparticles blended with microhybrid composite resin was confirmed for a duration up to 12 weeks.

INTRODUCTION:Occlusal veneer are considered promising solutions for coronal tooth structure loss. Pressed lithium disilicate is the first choice indirect restorative material. Resin cements are the weak point in this biomimetic solution. OBJECTIVES: Investigate the fracture resistance and shear bond strength of lithium di-silicate occlusal veneer using different dual cured resin cements. MATERIALS AND METHODS: 28 sound extracted human permanent molars were used. They were divided into 2 groups (n=14) according to 2 different tooth preparation. For group A the occlusal surface was anatomically reduced for fracture resistance test, while for group B the occlusal surface was flattened for shear bond strength test. Each group was divided into subgroups (n=7) according to resin cement system type used. For group A1 and B1, Panavia F 2.0 self-etch resin cement. While for group A2, B2 Variolink Ethetics total etch resin cement was used. Lithium disilicate veneers (1mm) and discs (2×4 mm) were cemented according to manufacturer's instructions. Bonded samples were tested for fracture resistance and shear bond strength after thermocycling. Failure mode was determined. The data were statistically analyzed (p≤0.05). RESULTS: Type of resin cement had a statistically significant difference on the fracture resistance and shear bond strength with P ≤ 0.05. Group (A2) Total etch Variolink Esthetic resin cement provided higher fracture strength (2259.5 N).Also, Group (B2) provided higher bond strength (34.36 MPa). CONCLUSION: The lithium disilicate occlusal veneers are preferred using total etch adhesive to get the best bond strength and fracture resistance sufficient to withstand loading in molar region.

Purpose: Evaluating the effect of various fiber reinforced composite (FRC) post surface treatments on its tensile bond strength to root canal dentin. Materials and method: Forty extracted human maxillary central incisors were selected. The coronal portion of each tooth was sectioned 15 mm coronally from the root apex. All root canals were instrumented, obturated and the post spaces were prepared to a depth 10mm. The specimens were classified into four groups according to the surface treatment. Group1:-surface treatment with plasma (argon plasma), Group2:-surface treatment with air born-particle abrasion, Group3:-surface treatment with air born -particle abrasion and silane, Group4:-control group without any surface treatment. Two randomly selected posts from each group were examined by Scanning Electron Microscopy (SEM). Self adhesive cement was used for cementation of all posts. Specimens were subjected to thermal cycling for a total of 5,000 cycles between 5 C and 55 C, with a 30-second dwell time, 20 sec transfer time at each temperature. The tensile bond strength test was performed using a universal testing machine at a cross-head speed 0.5 mm/min until failure occurred. Posts were examined under stereomicroscope to detect the mode of failure. The data were collected, tabulated and statistically analyzed. Results: The tensile bond strength of the luting agent to the post was significantly affected by surface treatment (P < 0.05). Plasma treated group showed the highest bond strength followed by air-born particle abrasion with silanization and air-born particle abrasion while the control group showed the lowest bond strength. Conclusion: Both plasma surface treatment and air-born particle abrasion with silane application improved the bonding of fiber post to the resin cement. The effect of plasma treatment was predominant.