Myelin-related disorders such as multiple sclerosis and leukodystrophies, where restoration of oligodendrocyte function would provide an effective treatment, are poised to benefit greatly from stem cell biology. Progress in myelin repair has been constrained by difficulties in generating pure populations of oligodendrocyte progenitor cells (OPCs) in sufficient quantities. Pluripotent stem cells theoretically provide an unlimited source of OPCs but current differentiation strategies are poorly reproducible and generate heterogenous populations of cells. Here we provide a platform for the directed differentiation of pluripotent mouse epiblast stem cells (EpiSCs) through a defined series of developmental transitions into a pure population of highly expandable OPCs in ten days. These OPCs robustly differentiate into myelinating oligodendrocytes in vitro and in vivo. Our results demonstrate that mouse pluripotent stem cells provide a pure population of myelinogenic oligodendrocytes and offer a tractable platform for defining the molecular regulation of oligodendrocyte development and drug screening.

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Dental plaque is considered to be a major etiological factor in the development of periodontal disease. Accordingly, the elimination of supra- and sub-gingival plaque and calculus is the cornerstone of periodontal therapy. Dental calculus is mineralized plaque; because it is porous, it can absorb various toxic products that can damage the periodontal tissues. Hence, calculus should be accurately detected and thoroughly removed for adequate periodontal therapy. Many techniques have been used to identify and remove calculus deposits present on the root surface. The purpose of this review was to compile the various methods and their advantages for the detection and removal of calculus.

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