Scaling and polishing: scaling is the mechanical removal of plaque and tartar (calculus) that has built up on your teeth.
Calcium and protein in saliva help maintain the health of your teeth, supporting structure and the oral tissues. If calcium and protein build up over time bacteria can also build up. The problem starts with a thin film along the gum margin, if the scale or tartar is allowed to accumulate on the teeth it will unfortunately provide the right conditions for bacteria to thrive next to the gum.
The purpose of scaling cleaning and polishing is to prevent gum disease as scaling and polishing leave the surfaces of the teeth clean and smooth so that bacteria is unable to stick. You also have a better chance of keeping the teeth clean during your regular home care.