The aim of this in vitro study was to determine the amount and duration of diffusion of calcium ions from both a calcium hydroxide-containing root canal sealer and an intracanal medicament, through the apical foramen and the dentinal tubules of endodontically-treated teeth. The root canals of 88 freshly extracted single-rooted teeth were prepared using the modified double flared, balanced force technique with patency filing. The teeth were divided into four test groups of 20 teeth each and a control group of eight teeth. One group was dressed with a non-setting calcium hydroxide while the other was obturated using cold lateral condensation of gutta-percha with a calcium hydroxide-containing sealer. An artificial root defect was created in the apical third of the root of the teeth in the other two groups and the root canals were either dressed or obturated in the same way as the first two groups. All groups were incubated at 37 degrees C and were sampled for calcium diffusion after 1, 2 and 3 days and 1, 2, 3, 4 and 8 weeks. There was statistically significantly more calcium diffusion with the non-setting groups compared with the sealer groups (P < 0.05). There was more calcium ion diffusion from teeth with a patent apical foramen than those with an artificial resorptive root defect (P < 0.05).

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There is no statistically significant difference between the orange oil and chloroform when used as solvent for removing gutta-percha.

Aim: There are various techniques to study root canal morphology and diaphonization is one of them. There are various methods of decalcification and diaphonization, cited in literature and the main aim of this paper was to give a brief account of the various techniques and share our experience of the technique at a teaching institution in Karachi, Pakistan. Materials and methods:Diaphonization is one of the oldest methods and is based on decalcification of teeth followed by clearing and dye penetration. The specimen is later studied under microscope without sectioning.Results: After the process of clearing a three-dimensional (3D) structure of the internal canal anatomy was visible with naked eye. Conclusion:This paper entails a detailed historical background as well as the author's technique including percentages of various chemicals used and the timing of immersion of teeth into these agents. Clinical significance:The read out is simple and can be subjected to interpretation by direct observation under microscope and can be helpful for students undertaking research in not only the discipline of dentistry but also in other fields such as botany and zoology.

Thermal desolvation of poly(N-isopropylacrylamide) (PNIPAM) in the presence of a low concentration of gold nanoparticles incorporates the nanoparticles resulting in suspended aggregates. By covalently incorporating <1% acenaphthylene into the polymerization feed this copolymer is enabled to be used as a model to study the segmental mobility of the PNIPAM backbone in response to gold nanoparticles both below and above the desolvation temperature, showing that there is a physical conformational rearrangement of the soluble polymer at ultralow nanoparticle loadings, indicating low affinity interactions with the nanoparticles. Thermal desolvation is capable of extracting >99.9% of the nanoparticles from their solutions and hence demonstrates that poly(N-isopropylacrylamide) can act as an excellent scrubbing system to remove metallic nanomaterial pollutants from solution.