Aims:The purpose of this study was to evaluate the effects of staining by coffee and In-office bleaching by 30% hydrogen peroxide on surface roughness of two different Nano Hybrid composite and Omnichroma resin-based composite. Materials and Methods: In this in vitro experimental study, 32disc samples were fabricated from each type of the Nano-Hybrid resin composite materials, each sample measured 5 mm in diameter and 2 mm in height. The samples for each composite group were then sub-divided randomly into four sub-groups (n=8). In control sub-groups, samples were stored in artificial saliva at 37°C for 1 week. Samples of Staining sub-groups were stored in a coffee solution for 48h at 37°C. Samples of Staining Bleaching sub-groups were stained in a coffee solution for 48 h at 37°C then bleached with 30% H2O2. Samples of Bleaching sub-groups were bleached with 30% H2O2. The surface roughness measurements were taken for all samples of each sub-group; the measurements for control sub-groups considered as baseline data. Non-parametric tests were used for statistical analysis at P≤0.05. Results: The surface roughness measurements of all sub-groups for both tested materials didn't exceed the critical value (Ra< 0.2 μm) with no significant difference among all sub-groups (P >0.05). Conclusion: Surface roughness of the two tested Nano-Hybrid resin composite materials were neither influenced by coffee staining nor by inoffice bleaching with 30% H2O2.

Background and Aims: Evaluate and compare the fracture resistance of endodontically treated teeth restored with bundle glass fiber post and tapered glass fiber post, at 45 degree oblique load. Materials and Method:Thirty newly extracted single rooted mandibular first premolars were chosen, and after root canal preparation and obturation, post spaces were prepared. Then the samples were separated into three groups (n = 10) dependent on the type of restorative method used: group A restored with Rebilda fiber post [tapered glass fiber post], group B restored with Rebilda post GT post system (bundle glass fiber post), and group C restored with direct composite resin restoration without a post (control). Using a universal testing machine with speed of 0.5 mm/minute at 45 degree sloping load which was applied to the restored teeth, fracture resistance was recorded in Newton. Results:The results showed that the fracture resistance significantly affected by different post systems (p < 0.05). The bundle glass fiber post (rebilda Gt) showed highest fracture resistance than the other groups. Conclusion:Rebilda GT post (bundle glass fiber system) showed higher fracture resistance than the Rebilda fiber post (tapered glass fiber post) and control group respectively.

A BSTRACT Background and Aims: Rising effects of temperature due to laser use during root canal disinfection may harm periodontium and alveolar bone. Therefore, the aim of this study was to estimate the surface root temperature of lower incisors throughout the application of different power levels and times of an 810-nm diode laser. Materials and Methods: Sixty single-rooted extracted human lower incisor teeth were selected and chemomechanical preparation was performed. Specimens were irradiated using 810-nm diode laser at 1.05, 1.5, and 1.95 W power settings and two periods of time 20 and 60s, in a continuous wave (CW) mode, without water spray. Specimens were divided into three main groups ( n = 20). Each group was subdivided into two subgroups ( n = 10). Then, the peak temperatures at the middle and apical regions of the root surface were registered using a thermocouple. Results: Temperature rise of root surface at all the selected output powers was below 7°C. The highest temperature value was obtained in the apical region at 60s when the root canal irradiated at 1.95 W output power. Conclusion: Diode laser is safe for use as a root canal disinfectant. Time of exposure to laser irradiation has an effect on the temperature difference at different output powers.

Aims: The study was conducted to evaluate the pH and antimicrobial properties of newly prepared calcium based cement, polycarboxylate cement and biodentine material. Methods: The new cement was prepared from egg shell, for pH measurements, 9 standard discs (6 mm in diameter and 2 mm in thickness) were prepared for each material, The antibacterial effects of set specimens against Streptococcus mutans, oral Lactobacillus and Enterococcus faecalis were assessed by agar diffusion tests, 90 discs shaped specimens (30 of each type of materials; 6 mm in diameter x 2 mm in thickness) were prepared. Three discs, one for each material was placed on each agar plate, and the plates incubated for 24 hours. After incubation, the diameter of inhibition zone was measured at three different points and the mean value was used as the result of the specimen. Results: Statistically significant differences were identified between cements, calcium based cement and biodentine exhibited higher mean values of pH than polycarboxylate cement, ANOVA and Duncan's multiple range test were done to evaluate the effect of materials against each type of bacteria, it showed that the inhibition zones produced by experimental cement were statistically significantly larger than those produced by the other materials. Conclusion: Within the limitation of this research, it was concluded that new calcium based cement has a better antimicrobial properties than biodentine and polycarboxylate cement.

Aims:To evaluate the effect of different surface treatment on the microleakage of repaired CI V composite resin restoration. Materials and methods: This study was performed in vitro on 20 caries free premolar teeth. Standardized class V cavity preparation on buccal and lingual surfaces of each tooth was done, forty cavities cleaned with distilled water and dried, then the cavities were filled with the composite. After that, all teeth were stored in normal saline for 3 months, so that the filling become old then remove 1mm of composite from all cavities. The cavities were divided into four groups. The first two groups were treated with 37% phosphoric acid. The other groups treated with 9% hydrofluoric acid the groups II and IV were treated with silane coupling agent, then all cavities were filled with composite after 5 th generation bonding agent were applied .The teeth were stored for one week after that the Samples were thermocycled and immersed in methylene blue dye, The samples were sectioned, and examined using stereomicroscope. Results: Samples treated with silane coupling agent showed less microleakage than those without silanation. There was highly significant difference between samples acid etched using hydrofluoric acid with those etched with phosphoric acid. Conclusions: Silane coupling agent and the hydrofluoric acid significantly decreased microleakage of repaired CI V composite resin restoration.