Tooth brushing one they feel comfortable with, determine what is affordable for them and will be more likely to regularly brush with. Toothbrushes are offered with varying textures of bristles, and come in many different forms and sizes. Most dentists recommend using a toothbrush labelled "soft", since firmer bristled toothbrushes can damage tooth enamel and irritate gums as indicated by the American Dental Association. Toothbrushes are often made from synthetic fibers, although natural toothbrushes are also known in many parts of the world. Those with dentures may also brush their teeth with traditional tooth brushes, specially made denture brushes or denture cleaners.
Active layer in permafrost regions due to the low rate of weathering in the very cold climate. The slow rate of decomposition of organic material means gelisols (permafrost soils) are very important as a sink for carbon dioxide. This carbon dioxide and other greenhouse gases (chiefly methane) forms from the very slow decomposition of the excess organic matter that remains in most gelisols and is mixed down into the pereletok layer during relatively hot summers and below that layer during warmer periods about 5000 to 6000 years ago. This storage of carbon means thawing of permafrost may accelerate global warming - some