Abstract: Aims: This study aims to evaluate the effect of (MRI) on physical, and mechanical properties of acrylic resin denture base materials. Materials and Methods: one hundred and ten samples were the total no. of samples, samples were divided into two groups each group contain two fifty five, the 1st sample group pink and 2nd groups clear heat cured acrylic resin, then the two groups is divided into four sub-groups, follow that the samples were exposed to magnetic resonance image at three different peri-ods of time (5, 15, 30) minutes within control group respectively and samples tested for indentation hardness, tensile strength. Results: the results obtained to show that there was a change in the physical properties “heat cured” acrylic resin weather it is “Pink” or “Clear” after exposure to (MRI) and this change happened at different levels and variable degree, also it has shown that there was a slight tendency to change order of a arrangement of atoms within each molecules with no well and clear evidence of altering of the main material itself, at least at circumstances of experiment. Conclusion: Exposure to (MRI) at different periods of time lead to altering of physical properties and at different levels of significant.

Abstract: Aims: To evaluate the effect of three different adhesive systems on shear bond strength of composite resin to Er,Cr:YSGG lased dentin. Materials and methods: Twenty one sound third molars were used. Occlusal third of crowns was cut using minitom machine to expose flat dentin surface. Laser irradiation was performed on a circular test area demarcated on each dentin surface. Samples randomly assigned to three groups (n=7) according to the adhesive systems that used which were: total etch adhesive (Adper single bond, 3M ESPE), two step self etch adhesive (Clearfil SE bond, Kurary), and all in one adhesive (Adper easy one, 3M ESPE). Adhesives were applied to the lased dentin surface according to manufacture instruction. Composite rod was applied over the bonded area and cured. Samples were stored in distilled water at 370for 24 hours. The evaluation of shear bond strength was employed by the use of universal testing machine. Results: Statistical analysis of data by analysis of variance (ANOVA) test and Duncanes multiple range test revealed no significant difference in the shear bond strength between the adhesive systems (P≤ 0.05). Conclusions: The results show that all the tested adhesive systems have relatively the same effect on the shear bond strength of composite resin to lased dentin surface.

Abstract: Aims: The aim of the study is to evaluate the effect of addition of some natural and beneficial oils (Castor oil, Grape seed oil and Fenufreek oil) in different concentrations (1.5%,2%,2.5%) on some properties (chemical structure, residual monomer, transverse strength and color change) of cold cured acrylic resin. Materials & Method: One hundred samples were prepared from Respal cold cured acrylic resin.Ten samples were the control, thirty samples were prepared with addition of each oil (ten samples for each concentration). Each group of samples were evaluated for chemical structure (by Fourier Transform Infrared Spectrophotometer), residual monomer (by U.V. spectrophotometer), transverse strength (by instron testing machine) and color change by (Vita easy-shade).Results: the results were analysed statistically by ANOVA and Duncan’s multiple range test. Conclusion: it’s shown that the Castor oil additive (2.5%) showed decrease in the residual monomer release and not significant difference in transverse strength, lightness, chroma and hue from the standard group.

Abstract: Aims: Evaluation of the stress in the bone and miniscrew displacement of 1.3 and 1.4 mm in diameter inserted in two bone models of 1 and 2 mm of cortical bone thickness at 90◦ angulation to the bone. Materials and Methods: The sample consisted of 20 models which were grouped into four groups, each group included five models. The bone models of different cortical thickness (1mm,2mm) were designed by a three dimensional Finite Element Analysis Program. The miniscrew models of 1.3 and 1.4 mm in diameter were created by the same program. Then inserting the threaded part of miniscrew in the bone block at 90°, and assigning the material properties and applying of 2N as an orthodontic force. Finally the stress distribution in the bone and miniscrew displacement in the different conditions were evaluated. the results were analyzed by using ANOVA and Duncan analysis. Results: The miniscrew diameter 1.4 mm inserted in 2 mm cortical bone thickness demonstrated the lowest bone stress and miniscrew displacement than the others. Conclusions: As cortical thickness and miniscrew diameter increased the bone stress reduced and less miniscrew displacement occurs.

Abstract: Aims: To evaluate wettability of flexible denture base martial after immersion in saliva, artificial saliva, chlorhexidine and sodium hypochlorite for 7 days period of time. Materials and methods: sixty rectangular shape sample of flexible denture base martial were prepared with one surface polished and another surface unpolished. These samples were stored in the previously mentioned four solutions in addition to the distilled water as a control group for 1 day and 7 days. Contact angle (parameter of wettability) were measured on both surfaces after each storage periods (1- day and 7 days). The statistical analysis to the data was performed using ANOVA and Duncan Multiple Range Test. Results: The results revealed that the wettability of unpolished flexible denture base material is significantly more than the polished surface. Sodium hypochlorite had significantly decrease the wettability of polished surfaces. Periods of storage had significant effect only on the wettability of polished surfaces rather than unpolished surfaces. Conclusions: Wettability of unpolished surface of flexible material is better than the wettability of the polished surface. The storage periods have no effect on the wettability of unpolished surface. Disinfectant solutions that have oxidizing effect (sodium hypochlorite) has a worsening effect on the wettability of flexible denture base materials.

Abstract: Aims: This study evaluated changes in working length (WL) and root canal dimension after instrumentation with hand instruments (St.St, NiTi) and rotary systems (RaCe, ProTaper). Materials and Methods: Twenty four resin blocks with a curve canal of 33°angle at (14mm) were selected for this study. Working length was measured by a digital measurement using a number (10k) file under stereomicroscope at 40X. The specific sequence of instrumentation was system according to manufacturer’s recommendation. The working length of the canal was measured again between each file and at the end of instrumentation. Pre and post-instrumentation microscopic photographs were taken and measurements of the root canal dimension change were measured with an image analysis programme . The difference in working length was analyzed using ANOVA and Duncan’s test at 5% level of significance. Result: Statistical analysis showed that there was no significance difference in the changing of the working lengths and canal dimension between the two rotary systems (ProTaper,RaCe). While there was a significant difference in the changing of the canal length and dimension between the two rotary systems (ProTaper,RaCe) and the hand instruments (St.St, NiTi). The amount of variation in working length and canal dimension obtained with both types of rotary instruments, was significantly less than that produced by hand instruments. Conclusion: The variation in working length were clinically not very significant between the two rotary NiTi instruments (ProTaper, RaCe)while it was significant with the hand instrument (St.St and NiTi).

Abstract: Aims: To compare the frictional forces between different types of aesthetic brackets and Nickel Titanium (NiTi) arch wires during leveling and alignment stage of orthodontic treatment. Materials and Methods: The sample of the study included three types of ceramic brackets: active self–ligating, monocrystalline and polycrystalline with metal slot in combination with 0.014” and 0.016” NiTi arch wires. The friction setup includes a custom–designed model with three nonleveled and nonaligned brackets. All tests were carried out in a dry state on a digital tensile testing machine. The data were analyzed using the descriptive and inferential statistical tests at (p<0.05) significance level. Results: The results demonstrated that there were statistically significant differences between the studied groups of brackets and arch wires (p<0.05). Conclusions: The combination of the active self–ligating ceramic bracket with 0.014” NiTi arch wire has the least frictional force in the leveling and alignment stage as well as the ceramic bracket with metal slot is a good alternative to solve the problem of friction.

Abstract: Aims: The aims of this study were to compare between the immunological parameters (serum interleukin-6 (IL-6) and c-reactive protein (CRP) of patients suffering from chronic cardiovascular diseases with amlodipine therapy and control group to determine the effects of the drug on those parameters. Materials and Methods: The study was conducted on 42 subjects, 27 patients already on amlodipine therapy, aged ranged between 34-75 years. Fifteen healthy subjects of the same age group participated in this study as a control group. The screening by medical history, examination (gingival enlargement scores) and blood samples to measure serum IL-6 and CRP was done once at base line visit. Results: The results obtained showed that amlodipine trherapy group had higher gingival overgrowth scores and immunological parameters than control group with significant difference at (p<0.05), also there was positive correlation but not significant between CRP in serum and IL-6 (p< 0.05). Conclusion: The study concluded that there is a significant difference in the GO score and immunological parameters in amlodipine therapy group as compared with healthy group.

Abstract: Aims: The aims of the present study were to describe the morphology of the cervical column in adult patients with a skeletal deep and normal bite occlusion, the prevalence of these morphology within them and to analyse the associations between the morphology of the cervical column and craniofacial parameters. Materials and Methods: The sample of this study composed of two groups, deep bite and normal over bite. The normal or control group composed of 50 adult subjects (25 males and 25 females) aged 18-25 years. The deep bite group composed of 59 adult subjects (20 males and 39 females) aged 18-25 years. Lateral cephalometric radiograph were taken for both normal and deep bite groups. We used 12 variables 11 angular and 1 linear measurements. The morphology of the cervical column was evaluated by visual inspection of the first five cervical vertebrae as they are normally seen in on a standardized lateral cephalometric radiograph. Results: In the skeletal deep bite group, 53.4 per cent had fusion of the cervical column and 23.2 per cent posterior arch deficiency (partial cleft). The fusion always occurred between C2 and C3. In the normal over bite group, 12.9 per cent fusion of the cervical column and 5.35 per cent of posterior arch deficiency, the fusion always occurred between C2 and C3. The significant correlations were seen between fusion and the angle between palatal plane and mandibular plane, the angle formed between the long axis of upper central incisor and palatal plane and the distance between the incisal edges of upper and lower central incisors, also the significant correlation between posterior arch deficiency and the angle between palatal plane and mandibular plane, the angle between the mandibular plane and chin line, gonial angle and the angle formed between the long axis of upper central incisor and palatal plane. Conclusions: The deep bite group had more deviations of the cervical column than the normal group. Our results showed that the craniofacial parameters, occlusion and malformations of the jaws were affected by morphological deviations of the upper cervical vertebrae including fusion and posterior arch deficiency.

Abstract: Aims: Tensile bond is important for assessing the success of adhesive restorative materials. The aim of this study is to evaluate the tensile bond strength of resin composite restoration to Er,Cr:YSGG lased dentin bonded with three types of adhesive systems. MATERIALS AND METHODS: Occlusal enamel of eighteen molars samples was removed to expose the underlining dentine. Er,Cr:YSGG laser irradiation was performed to central dentin. Samples were assigned randomly to three groups (N = 6): Group Ι: dentin was treated total etch adhesive (Adper single bond, 3M ESPE); Group II: treated with all in one self—etch adhesive (Adper easy one, 3M ESPE); Group III: treated with two step self—etch adhesive (Clearfil SE bond, Kurary). A translucent plastic tube was fixed and filled incrementally with hybrid resin then small metal screw with ring head was embedded in last increment. Samples were stored in distilled water at 37°C for 24 hours. Tensile bond strength was measuredd using universal testing machine (Digital Force Gauge IMADA CO., LTD, Japan), the failure mode was evaluated. Then statistical analysis was done include descriptive, one way analysis of variance test, and Post Hoc tests. RESULTS: A significant differences in tensile bond strength were observed among groups (p < 0.05). Total etch adhesive bonded demonstrate significantly higher tensile bond strength value than one step self–etch and two step self–etch adhesives (p < 0.05). No significant differences were observed between one step self–etch and two step self–etch adhesives (P>0.05). CONCLUSION: The tensile bond strength of resin composite to Er,Cr:YSGG lased dentin was influenced by adhesive type. Total etch adhesive bonded had higher tensile bond strength than one step and two steps self–etch adhesives.