Influence of filled versus unfilled adhesives on bond strength to dentin and evaluation of the hybrid layer by laser Raman spectroscopy

The purpose of this study was to evaluate the effects of filler incorporation in the adhesive materials i.e., unfilled, microfill and nanofill adhesives, on their shear bond strength to dentin and the chemical nature of the hybrid layer using the micro-Raman spectroscopy

Materials and methods: For bond strength test, the buccal surfaces at a total of 60 freshly extracted non-carious human molar teeth were ground flat. Teeth were divided into three group [n=20] according to the adhesive systems used; prime and Bond 2.1 [unfilled], Optibond Solo [microfill] and XenoIII [nanofill]. The composite resin was applied to the bonded surfaces and light cured. Shear bond strength test was performed using the universal testing machine. For the Raman spectroscopic examination, the occlusal surfaces of a total of 30 freshly extracted human molar teeth were ground flat. Teeth were divided into three groups [n=10] according to the grouping system mentioned before. The adhesive systems were applied to the occlusal surface, and then thee composite resin was applied to the surface and light cured. The specimens were sectioned parallel to the dentinal tubules, the sectioned surfaces of the cut halves were polished with silicon carbide papers. The prepared specimens were examined using the Raman spectroscopy

Results: The results of the present study revealed that the nanofill adhesive system revealed the highest mean shear bond strength values and the lowest values of Residual Double Bond RDB. The microfill adhesive system revealed the lowest mean shear bond strength values and the highest values of RDB. The unfilled adhesive system revealed intermediate results in-between the nanofill and the microfill

Conclusion: Within the limits of the present study it was evident that; Addition of fillers with nanometer particle size to the adhesive system will enhance excellent bonding and sealing of restoration to dentin. Addition of fillers with nanometer particle size to the adhesive system will enhance excellent bonding and sealing of restorations to dentin. Addition of fillers with micron particle size to the adhesive system will impair bonding and sealing of restorations to dentin. The shear bond strength test when combined with microscopic analysis of the adhesive tooth interface can provide useful information regarding the bonding mechanisms of adhesives. The laser Raman spectroscopy is a useful analytical technique for studying the bonding structure of specimens and determining their composition. Further studies are needed to determine the relationship between the amount of residual double bonds and bond strength durability

study of potential hazards of frequency doubled Nd: YAG laser and near infra-red diode laser on the eye in laser labs

Two laser systems were used to study the effect of direct hit to the retina of experimental animals. Laser parameters were considered; the energy/pulse and distance for frequency doubled Nd:YAG laser and power for Diode laser. Our study aimed to access effects of accidental exposure of the eye to laser beam in labs and calculate minimum distance and maximum intensity that can cause permanent damage. Thirty two rabbits divided into: Group I: Exposed to 532 nm Nd:YAG, at different distances from 1 to 750 meters without focusing. Group II: Exposed to 808 nm diode laser using intensities 0.3 watts to 2.5 watts. Frequency Doubled Nd:YAG showed a clear dependence on the energy per pulse; while Diode laser; as a CW laser gave a constant effect regardless of the power. Nd:YAG and Diode Lasers showed strong damaging effect on retina depending on peak power of single shot in first case and average power in second case during exposure

In-vivo genotoxicity of the synthetic pyrethroid pesticide "cypermethrin" in rat liver cells by comet assay

The comet assay [single-cell gel electrophoresis, "SCGE"] is a simple method for measuring deoxyribonucleic acid [DNA] strand breaks in eukaryotic cells. The assay has applications in testing different chemical and physical agents for genotoxicity and monitoring environmental contamination with genotoxins. The objective of the present study was to evaluate the genotoxic effects of the synthetic pyrethroid pesticide "cypermethrin ", which is widely used in Egypt in pest- control programs in agriculture and in public health as well. Male rats were sacrificed 1, 7 or 14 clays after administration of single oral dose 1/30, 1/10 or 1/5 LD50 of commercial formulation of cypermethrin. Single liver cell suspensions were prepared and Comet assay was performed. With the SCGE assay, a clear induction of DNA damage was observed. It is generally noticed that all pesticide treatments yielded statistically significant [p<0.0001] DNA damage. In conclusion, cypermethrin induced a clear significant positive dose-dependent increase in DNA damage in the rat liver cells exposed to cypermethrin as compared with controls. But the effects in the SCGE were generally decreased with time after treatments. The results of the present work suggested that comet assay might be a suitable and sensitive endpoint in genotoxicity evaluation of pesticides, but we confirm that various tests should be used for detecting the mutagenic activity of pesticides

Transmyocardial laser revascularization [TMR]; is a novel option of patients having advanced ischemic heart disease with intractable angina and poor left ventricular function

TMR is a successful treatment for chronic refractory angina in patients having diffuse CAD, not amenable to PTCA or CABG and exhausted drug therapy, but still having normal or nearly normal left ventricular [L.V.] function However in our practice in Egypt, we have to perform TMR for patients having severely diffuse CAD with poor L.V. function. This study was done to determine the clinical outcome of TMR for patients having end stage CAD and poor L.V. function Out of one hundred patients had CAD not amenable to PTCA or CABG underwent sole TMR with a CO2 laser [the heart laser system P.L.C. medical system]. Twenty five patients had a high score of medical therapy with preoperative special anesthetics management and using of GIK intravenous infusion as a metabolic support for the myocardium in addition to long term postoperative rehabilitation program. The results showed that, there was no operative or postoperative mortality and considerable early post operative morbidity. Follow up of the patients up to 12 month showed [1] reduction of 2 or 3 angina classes as compared with preoperative state. [2] improvement exercise tolerance. [3] decreased of Cardio- active medication. [4] improvement of myocardial perfusion of the lazed areas. It was concluded that the, TMR has emerged as an effcient treatment for patients with interctable angina and low ejection fraction