What is scaling for, and is it unpleasant?
Scaling removes the tartar that brushing cannot remove. It protects the gums. How it feels depends on the amount of tartar and your sensitivity; it generally remains tolerable.
Everyday care and prevention
Plaque that is not removed every day eventually hardens into tartar, especially near the gums and behind the lower teeth. Tartar no longer comes off with brushing and keeps the gums inflamed.
Scaling consists of removing this tartar with suitable instruments, often ultrasonic ones, then polishing the teeth to smooth their surface. It also removes some of the staining caused by tea, coffee or smoking.
How it feels depends on the amount of tartar and the condition of the gums. Vibrations, a little sensitivity or slight bleeding are common. If you are sensitive, say so: the dentist can adjust the settings or offer local anaesthesia for the area.
Scaling does not damage the enamel. Carried out regularly, generally once or twice a year depending on the case, it helps keep the gums healthy.
This is a general answer. Only a consultation at the practice can tell what suits your situation.