In dentistry, calculus or tartar refers to hardened plaque on the teeth, formed by aging in the presence of saliva, debris[?], and minerals. Its rough surface provides an ideal medium for bacterial growth, threatening the health of the gums[?] and absorbing unaesthetic stains far more easily than natural teeth.
All Wikipedia text
is available under the
terms of the GNU Free Documentation License
Search Encyclopedia
Search over one million articles, find something about almost anything!
... human female, the urethra is about 1-1.5 inches (25-38 mm) long and opens in the vulva between the clitoris and the vaginal opening.
In the human male, the urethra is ...