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ObjectivesTo evaluate the effects of copolymer of acrylic acid and maleic acid (Poly[AA-co-MA]) and calcium hypochlorite (Ca(OCl)2) on root canal dentin using scanning electron microscope (SEM).Materials and MethodsTwenty-four single-rooted teeth were instrumented and the apical and coronal thirds of each root were removed, leaving the 5 mm middle thirds, which were then separated into two pieces longitudinally. The specimens were randomly divided into six groups and subjected to each irrigant for 5 min as follows: G1, Ca(OCl)2; G2, Poly(AA-co-MA); G3, Ca(OCl)2 + Poly(AA-co-MA); G4, sodium hypochlorite (NaOCl); G5, ethylenediaminetetraacetic acid (EDTA); G6, NaOCl+EDTA. The specimens were prepared for SEM evaluation. Smear layer, debris and erosion scores were recorded by two blinded examiners. One image from G3 was analyzed with energy dispersive spectroscopy (EDS) on suspicion of precipitate formation. Data were analyzed using the Kruskal-Wallis and Dunn tests.ResultsG1 and G4 showed the presence of debris and smear layer and they were statistically different from G2, G3, G5 and G6 where debris and smear layer were totally removed (p < 0.05). In G1 and G4, erosion evaluation could not be done because of debris and smear layer. G2, G3 and G5 showed no erosion, and there was no significant difference between them. G6 showed severe erosion and was statistically different from G2, G3 and G5 (p < 0.05). EDS microanalysis showed the presence of Na, P, and Ca elements on the surface.ConclusionsPoly(AA-co-MA) is effective in removing the smear layer and debris without causing erosion either alone or with Ca(OCl)2.

Crosslinked poly[2-(tert-butylamino)ethyl methacrylate] (PtBAEMA) hydrogels were synthesized by 60 Co-g-radiation-initiated simultaneous polymerization and crosslinking of 2-(tert-butylamino)ethyl methacrylate in bulk and in aqueous solutions. The results showed that the gelation percentage decreased with increasing water content. The structural and thermal characterizations of the hydrogels were accomplished with several techniques, including Fourier transform infrared spectroscopy, swelling measurements, thermogravimetry, and differential scanning calorimetry. The effects of time, pH, temperature, and ionic strength on the swelling behavior were also investigated. Swelling equilibrium was attained in 2-3 days. PtBAEMA hydrogels originally swelled to 350% (by volume) in deionized water, but this value reached 3000% around pH 2.0. PtBAEMA hydrogels were reversibly affected by the change in temperature within the temperature range of 4-708C. The swelling ratios of the gels decreased with increasing ionic strength. As a result, PtBAEMA hydrogels show stimuliresponsive properties depending on the characteristics of the environment, and they are being considered for adoption as some kind of carrying material for separation.

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