Dental Materials
Seyed Mohammad Mousavi; Sara Mahboubi; Salmeh Kalbassi; Vahid Rakhshan
Abstract
Background and aim: Elastomeric chains are crucial to orthodontics. Hence, their efficacy and force decay should be investigated. In this regard, chain morphologies and stretching extents are not assessed adequately. Therefore, we aimed to assess these parameters. Materials and Methods: Two-hundred-and-seventy ...
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Background and aim: Elastomeric chains are crucial to orthodontics. Hence, their efficacy and force decay should be investigated. In this regard, chain morphologies and stretching extents are not assessed adequately. Therefore, we aimed to assess these parameters. Materials and Methods: Two-hundred-and-seventy elastics from 3 brands [Ortho Technology (OT), American Orthodontics (AO), G&H, 10 specimens×27 subgroups] were stretched for 40%, 60%, and 100% elongations. Their initial forces were measured. After 4 weeks of incubation in artificial saliva, their residual forces were measured. Forces and force decays were compared across brands, morphologies, and stretching extents (α=0.001).Results: Forces degraded significantly over time (repeated-measures ANOVA, P<0.001). There were significant differences among levels of all parameters, in terms of the initial forces, residual forces, and force degradation (3-way ANOVA, P<0.001). Most of Tukey post hoc tests were significant (P<0.001). The longer the stretching extent, the higher the force waste (partial correlation coefficient, r=0.885, P< 0.001).Conclusion: The initial force was improved when using the OT brand, utilizing closed chains, and by elongating the elastic for 100%. Force loss would be minimized using the G&H brand, open elastics, and 40% elongations. Using OT, closed elastics, and 100% elongations would cause the highest residual forces after a month. However, the initial forces provided by the 100% elongations would not be much healthy. Force loss would be increased while using OT brand, using closed elastics, and with 100% elongations. The lowest residual forces were seen in the AO brand, long elastics, and those stretched for 40%.
Dental Materials
Neha Kaswan; Preeti Munjal; Puja Khanna; Sunny Mittal; Nishtha Arora; Sumit Chhabra
Abstract
Background: The objective of present study was to qualitatively and quantitatively evaluate the surface irregularities produced by three different methods of IPR followed by polishing and sealant application, using Scanning Electron Microscope (SEM) and Profilometer.Methods: The study sample comprised ...
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Background: The objective of present study was to qualitatively and quantitatively evaluate the surface irregularities produced by three different methods of IPR followed by polishing and sealant application, using Scanning Electron Microscope (SEM) and Profilometer.Methods: The study sample comprised of 100 extracted permanent maxillary 1st premolar teeth divided into 10 groups with 1 control group and 9 experimental groups according to the stripping method employed (hand-pulled abrasive strips, air rotor stripping and IPR file system) and subsequent finishing procedures (sealant application and polishing strips). The statistically significant intergroup comparison for the difference of mean scores between independent groups and difference among groups was determined by t test, one-way analyses of variance (Anova) and Tukey HSD Post Hoc test at level of significance set at 5%. or p < 0.05.Results: Surface roughness value (Ra) obtained using Profilometer and SEM images at 500x and 1500x magnification of IPR using diamond burs followed by sealant application (Group 7) had reasonably smooth surface. IPR File System when used with non-possibility of carrying out any adjunct finishing procedures (Group 4), disturbed the enamel surface to the least.Conclusion: Finishing procedures used post IPR gave smoother enamel surfaces making it necessary for reduction of number and depth of grooves created by IPR. Best combination which produced minimal enamel surface roughness post IPR in present study was diamond burs followed by sealant application.
Dental Materials
Hooman Shafaee; Fahimeh Farzanegan; Mohammad Sadegh Nazari; Erfan Bardideh; Jalil Tavakkol Afshari; Fatemeh Azani
Abstract
Background: The aim of study was the biological assessment of cultured RAW264 macrophage exposed to nano amorphous calcium phosphate particles by analyzing of cytotoxicity and genotoxicity tests.Methods: Nanoamorphus Calcium Phosphate particles were produced by sol-gel method, then particle size and ...
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Background: The aim of study was the biological assessment of cultured RAW264 macrophage exposed to nano amorphous calcium phosphate particles by analyzing of cytotoxicity and genotoxicity tests.Methods: Nanoamorphus Calcium Phosphate particles were produced by sol-gel method, then particle size and hemogenicity was analyzed by XRD (X ray Diffraction). Cytotoxicity of nanoparticles was determinated with mouse RAW264 macrophage. The cells cultured in 37°c in DMEM medium 96 parts plates with concentration of 10000 cells in each part for 72 hours, then the medium removed and the second medium added to cells containing different concentrations of Nano particle (0, 200 and 400µg/ml). After 24 hours of incubation, MTT assay and Annexin V were used for assessing cell viability and apoptosis.Results: The apoptosis insignificantly increased in macrophages with 200 and 400µg/ml NACP and for cytotoxicity, cell viability for control, 200µg and 400µg groups were 100,107,103 percent.Discussion: NACP has no cytotoxicity and genotoxicity, so it can be used as non-toxic and beneficial material for clinical use.
