The toothbrush is a brush used to clean teeth. Toothpaste, often containing fluoride, is commonly added to a toothbrush to aid in cleaning. Most dentists recommend using a toothbrush labelled "Soft", since harder toothbrushes can damage teeth and gums.
Many traditional cultures around the world have always cleaned their teeth by rubbing twigs or pieces of wood against them since ancient times. Rubbing baking soda or chalk against the teeth was also common.
According to the American Dental Association, the first toothbrush was made in 1498 for an emperor in China who had hog bristles embedded in a bone handle. They were not common in the West until the 17th century, and became much more common in the 19th century. (A common older method of tooth cleaning, by rubbing with a piece of rag cloth, was in use in Europe at least since Roman times).
The first patent for a toothbrush was by H. N. Wadsworth in 1850 in the United States, but mass production of the product only started in 1885. The rather advanced design had a bone handle with holes bored into it for the Siberian Boar hair bristles. (Boar wasn't an ideal material; it retained bacteria, it didn't dry well, and the bristles would often fall out of the brush).
It wasn't until World War II that the concept of brushing teeth really caught on in the US, in part due to the fact that it was part of American soldiers' regular daily duty to clean their teeth. It was a practice that they brought back to their home life after the conclusion of the war.
In January 2003, the toothbrush was selected as the number one invention Americans could not live without, beating out the automobile, personal computer, cell phone, and microwave, according to the Lemelson-MIT Invention Index.