Bücher von Amer A Taqa

The objective of this study is to prepare a chemical compounds for cleaning denture from locally available materials. The chemical compounds solutions were (sodium bicarbonate + alum), (sodium bicarbonate + citric acid), (sodium bicarbonate + apple vinegar), (sodium bicarbonate + clear commercial vinegar), (sodium bicarbonate + thyme oil), (saturated salt solution), (clear commercial vinegar), (alum). In addition, in the main study, the effects of the chemical compounds solutions were evaluated on the (color, water Sorption and transverse strength) of heat ¿ cured denture base material. The t-test showed that the highest increase in optical density for the specimens immersed in (alum), (sodium bicarbonate +alum), (sodium bicarbonate + apple vinegar) solutions at 1/2 hr immersion and it increased more at 8 hrs immersion. The conclusions of this study showed that the safest prepared solutions on the denture base material that could be used as denture cleansers are (sodium bicarbonate{7g}+ clear commercial vinegar{5ml}), (sodium bicarbonate {2g} + thyme oil {3.57g}), (saturated salt solution {40g}) at 1/2 hr and 8 hrs of immersion.

The aim of this study was to determine the effect of some chemical materials on the physical and chemical properties of dental stone. Accordingly, three types of chemical materials (rosin, nigella stavia oil and sodium lauryl sulfate) were incorporated into three kinds of type III dental stone (Zeta, Elite and Dental stone) at four concentrations. The physical properties evaluated were water-powder ratio, setting time, setting expansion, compressive strength and hardness. The evaluation of chemical properties was done by the use of infrared and ultraviolet spectrophotoscopy.The results revealed that the incorporation of these chemical materials into each type of dental stone resulted in changing their evaluated physical properties; this change varies with the type, concentration of the added chemical material and type of dental stone being used. The change in the physical properties has been shown to be correlated with the changes in the chemical structure of dental stone as it became clear by comparing the ir-specra and uv-spectra of dental stone before and after the addition of the chemical materials.

This study aims at evaluating bracket¿s slot dimensions ¿width, depth and labiolingual inclination¿, bracket¿s base curvature, bracket¿s interwing gap distance, bracket¿s colour, weight, microscopical evaluation of pad area and tensile bond strength after recycling the stainless steel and pure titanium brackets with different bracket recycling procedures, also evaluating bracket dimensional changes after debonding with bracket debonding pliers. No significant bracket measurement changes were occurred when utilizing bracket debonding pliers in debonding the stainless steel and pure titanium brackets. Finally, the conclusions of this study were that the microetcher method is the most effective in removing the adhesive remnant and has no significant change to the bracket measurements and the bracket removing pliers was strongly recommended in debonding the metal bracket and specially when debonded bracket is indicated for recycling.

The aims of this study are modification of locally available denture adhesives material by addition of additives (thymol, sodium fluoride and chlorhexidene) in a concentration of 2% with evaluation of some physical, chemical and biological properties of these materials using Fittydent, Bonyplus and Calcident as comparison groups. These measurements include: pH, density,viscosity, toxicity, antimicrobial effects ,infrared and ultraviolet spectra of all denture adhesive materials. The retentive ability of these materials are also measured and correlated with their viscosity. The results of this study revealed that all the materials tested have nearly a neutral pH. Bonyplus, CMC with thymol, CMC with chlorhexidine and (CMC with thymol, sodium fluoride and chlorhexidene) showed a significant antimicrobial effect. The spectrophotometric result indicated that the modified materials have similar structures to the commercial adhesives.

study was to evaluate the effects of adding chemical additives on the thermal, mechanical and chemical properties of dental plasters.This study included the evaluation of the following properties: W/P ratio, setting temperatures, setting time, setting expansion, compressive strength, surface hardness and infrared spectroscopy of the prepared samples. The results revealed that the inclusion of additives changed some of the evaluated properties, these changes correlated with the modifications seen in the Infrared spectra charts of the studied groups.It was concluded that both types of dental plasters produced setting temperatures lower than that of the dental stones (control group) and their setting temperatures were more suitable for wax pattern than that of stone but with additives the setting temperature will be increased and this belong mainly to the changes in the chemical structure of the gypsum.Also the mechanical properties of Al-Ahliyah plaster (Iraqi plaster) could be improved by the addition of some additives like rosin and gum Arabic.

The aims of this study were to detect the amount of fluoride released from the tested materials into three different storage solutions and to determine the change in the surface microhardness after storage.The amount of fluoride released from the three materials was significantly higher in acidic solutions than in neutral solutions. The Compomer released the highest amount of fluoride into the three storage solutions, while the least fluoride release was from the resin-modified glass-ionomer. The surface microhardness of the three tested materials reduced significantly after storage in neutral and acidic solutions compared to dry stored specimens. In acidic solutions, the surface microhardness was significantly lower than in neutral solutions. The Compomer showed the highest microhardness number values.

By clinical oral examination, some of the physical and biochemical analysis of human unstimulated whole saliva have been studied with their effects on the retention of acrylic denture base. The following parameters were studied: flow rate, pH, total protein, density, surface tension, viscosity and film thickness. Total protein concentration was found to be responsible for physical and chemical changes specially viscosity. There was a direct positive correlation between total protein and surface tension, viscosity, density and film thickness, while there was a negative correlation between total protein and with flow rate and pH. The results indicated that in both the first and the third groups, the physical and mathematic analysis for retention showed non significant changes while in the second group showed significant changes. The results in all groups showed that there was a positive correlation between force and wetted area and this force was due to wettability and not to water sorption.

This study aims to: 1- Modify Iraqi natural waxes by adding some natural and chemical materials in order to produce new experimental modelling waxes that can be used in dentistry. 2- Evaluate the new waxes by measuring the physical properties according to ADA specification No. 24 and ISO 1561. 3- Evaluate the manipulation of the prepared experimental modelling waxes in constructing maxillary completely edentulous record base.The results showed that the addition of 20% Na-CMC, 20% gum Arabic, and 20% rosin to hard paraffin led to decrease the maximum melting point, flow, thermal expansion and dimensional changes but increase the minimum melting point and hardness of the hard paraffin. The starch is the same as other additives except that it leads to decrease the minimum melting point but increase the maximum melting point and the thermal expansion of hard paraffin. The rosin is the most effective one on the properties of hard paraffin than other additives. It was concluded that the experimental modelling waxes:(hard paraffin beeswax) and (beeswax+starch) have the most nearest properties to control and ADA specification than other waxes

The aims of this study are to modify heat cured acrylic resin denture base material into a flexible heat cured acrylic resin material by using additives {Flavoring agents and Plasticizer and to study some of it''s physical and mechanical properties.One hundred sixty of heat cured samples and standard flexite have been prepared for studying some physical properties and tensile strength. The samples have been tested to measure (Tensile strength, Water sorption, Solubility, Color change, Dimensional accuracy). The results of this study have shown that the tensile strength of heat cured acrylic resin with additives was significantly lower than the standard heat cured acrylic resin while standard flexite group was significantly higher than standard heat cured acrylic resin. For dimensional accuracy, water sorption and solubility test, the group has shown significantly lower dimensional change,water sorption and solubility than other groups with additives but still higher than control group and flexite (valplast) one during seven days periods.For color change test there has been a change in color between groups that even cannot be considered.

The aims of this study are to investigate the effect of light intensity, curing time and combined effect of light intensity and curing time on the degree of conversion, depth of cure and amount of residual monomer released from composite samples cured with different light curing units. Single light cured composite restorative material (Herculite XR) exposed to different types of light curing units (Optilight LD, ULTRA-LITE 200 E plus, Astralis-VIVADENT) at a different exposure times (20, 40 and 60 seconds). The degree of conversion of composite resin samples was investigated by Fourier-transform infrared spectroscopy.The depth of cure of composite resin samples was investigated by scraping technique using a digital caliper. While the amount of residual monomer released from cured composite samples was investigated through measuring the released residual monomer in doubled distilled water with (CECIL 2000) ultraviolet visible spectrometer. The results it was shown that the low intensity LED LCU (Optilight LD) exhibit a non significant result in degree of conversion from those of high intensity (LED and QTH) LCUs at extended period of curing time.

The aims of this study were to evaluate the effect of change in time ,temperature (increase or decrease) and some additives(Nigella sativa and Thyme oil) on the degree of conversion, residual monomer release, transverse strength, indentation hardness, volumetric and color changes of the vertex heat cured acrylic resin.The results of the present study were analyzed statistically by (Descriptive statistics, ANOVA and Duncan¿s multiple range test). The results of this study showed that both changes in time and temperature showed significant changes in the degree of conversion, residual monomer, transverse strength, volumetric and color changes in the three curing cycles without additive. The used additives (Nigella sativa and Thyme oil) increased the conversion, increased the residual monomer release, showed a slight increase in volumetric change for the short cycle,(0.35-1.05) for the rapid simplified and for the regular curing cycles in comparison with their standard curing cycles without additives and color change, ¿E =3.376 (which is an acceptable change in vitro) for the Thyme oil additive to the regular heat curing cycle in comparison to the standard short cycle.