The document discusses ultrasonic scalers, including their definition, types, parts, differences from manual scalers, advantages, disadvantages, and tips. Ultrasonic scalers use high-frequency vibrations to remove plaque, calculus, and inflamed tissue from teeth and gums. There are two main types - piezoelectric and magnetostrictive. Key parts include the handpiece, cable, water control, power switch, and tips. Ultrasonic scalers are more efficient than manual scalers at removing calculus, require less space, and reduce treatment time and operator fatigue. However, they require water evacuation and can produce contaminated aerosols. The document also outlines four common types of ultrasonic