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.
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... legislatures in Canada when it was adopted by the British Parliament in 1982 (though as part of the Canada Act (UK) 1982 it only became law in Canada, not the United ...