Please explain if it is true that ultrasonic scalers can only remove 50% of total tartar buildup?

Ultrasonic: When removing tartar bu with hand instruments or the uss we can only remove what we can see and feel. The uss removes the stain, 'rocks'/'boulders'. Hand instruments remove the 'sand'/'pebbles'. With modern techniques and giving each patient the time they need for their cleaning we can remove 95% or more of the bu. See your dentist and get the time you need.