ABSTRACT
OBJECTIVE: To establish a method for simultaneously detecting methyl methacrylate, ethyl methacrylate, n-propyl methacrylate and butyl methacrylate in workplace air by a portable gas chromatography-mass spectrometer(GC-MS) technique. METHODS: The portable GC-MS hand-held probe was used for sampling and detection. Samples were separated with DB-5 rapid chromatographic column in order to maintain retention time and characteristics of the ions, and quantified by standard curve method. RESULTS: The linear correlation of this method was higher than 0.999 0. The minimum detection concentration was 0.03-0.06 mg/m~3, and the minimum quantitation concentration was 0.10-0.20 mg/m~3. The standard recovery rate was 82.22%-91.24%. The within-run and the between-run relative standard deviation were 7.67%-14.63% and 10.40%-13.79% respectively. CONCLUSION: The portable GC-MS technique could be used for qualitative and quantitative detection of above-mentioned four methylacrylate compounds in workplace air.
ABSTRACT
Objective@#To develop a solvent desorption-gas chromatography method for determination of ethyl methacrylate(EMA) in workplace air.@*Methods@#EMA in workplace air was captured by charcoal tubes and desorbed with carbon disulfide, separated through capillary chromatographic column, and then analyzed by gas chromatography-flame ionization detector.@*Results@#The linear ranges of EMA were 0.00-9108.00 mg/L, and the related coefficients were 0.999 96. The relative standard deviations(RSD) within the group were 0.55%-1.84%, and the RSD between the group were1.26%-3.30%. The average desorption efficiencies were 98.26%-100.58%. The average samplingefficiencies were 99.98%-100.00%. and the minimum detectable concentration and the minimum quantification concentration were respectively 0.03 mg/m3 and 0.10 mg/m3 per 3.00 L of air. The samples could be stored at room temperature for 7 days.@*Conclusion@#This method could be used formonitoring of EMA in workplace air.
ABSTRACT
Background: The esthetic quality of a restoration may be as important to the mental health of the patient as the biological and technical qualities of the restoration are to his physical or dental health. In Conservative Dentistry; to mimic, repair and reconstruct the natural tooth structure for the long term, would be based on the use of a restorative material retained only by an adhesive system, whether in load bearing or non-load bearing environments. To achieve high strength, bonds between tooth structure and restorative materials have been a long term goal of dental profession. Aim: The aim of this in vitro study was to compare the shear bond strength of two different dentin bonding agents with two different desensitizers. Materials and Methods: Eighty molars were taken, which were ground to expose dentin. The teeth were divided into two major groups. Each major group was subdivided into four subgroups of 10 samples each. Groups Ia and IIa were treated as dry bonding groups, groups Ib and IIb were treated as moist bonding groups, group Ic and IIc were rewetted with Gluma desensitizer, and groups Id and IId were rewetted with Systemp® desensitizer. Major group I was treated with Gluma comfort bond and Charisma. Major group II was treated with 3M ESPE Adper™ Single Bond 2 and 3M ESPE Filtek™ Z250. The samples were thermocycled and shear bond test was performed using Instron machine. The data was analyzed using one-way analysis of variance and Tukey’s significant different test. Results: The results revealed that the specimens rewetted with Gluma desensitizer showed the higher shear bond strength compared to all other groups, irrespective of the bonding agent or composite resin used. Conclusion: It can be concluded that the moist or rewetting technique could preserve the micro-morphological integrity of the collagen resulting in the optimum penetration of adhesive resin into the demineralized layer, thus, giving higher bond strength.
ABSTRACT
Background & Objective: The aesthetic quality of a restoration may be as important to the mental health of the patient as the biological and technical qualities of the restoration are to his physical or dental health. In Conservative Dentistry; to mimic, repair and reconstruct the natural tooth structure for the long term, would be based on the use of a restorative material retained only by an adhesive system, whether in load bearing or non-load bearing environments. To achieve high strength, bonds between tooth structure and restorative materials have been a long term goal of dental profession. Objective is to compare the shear bond strength of two different dentin bonding agents with two different desensitizers. Methodology: Eighty molars were taken, which were ground to expose dentin. The teeth were divided into two major groups. Each major group was subdivided into four subgroups of 10 samples each. Groups Ia and IIa were treated as dry bonding groups, groups Ib and IIb were treated as moist bonding groups, group Ic and IIc were rewetted with Gluma desensitizer, and groups Id and IId were rewetted with Systemp® desensitizer. Major group I was treated with Gluma comfort bond and Charisma. Major group II was treated with 3M ESPE Adper™ Single Bond 2 and 3M ESPE Filtek™ Z250. The samples were thermocycled and shear bond test was performed using Instron machine. The data was analyzed using one-way analysis of variance and Tukey’s significant different test. Results: The results revealed that the specimens rewetted with Gluma desensitizer showed the higher shear bond strength compared to all other groups, irrespective of the bonding agent or composite resin used. Conclusion: It can be concluded that the moist or rewetting technique could preserve the micromorphological integrity of the collagen resulting in the optimum penetration of adhesive resin into the demineralized layer, thus, giving higher bond strength.