‫عبداملنعم اخلفاجي‬
Lec.3
Powered cutting equipment
Handpiece:
Is a device for holding rotary instruments, transmitting power
(Source of power is motor or air) to them, and for positioning them
intraorally. Handpieces and associated cutting and polishing
instruments developed as two basic types, straight and angle.
Rotary speed ranges
Three speed ranges are generally recognized measured in
revolutions per minute (rpm)
1- Low speed or slow speeds: (below 12,000 rpm.) Used for tooth
cleaning, caries excavation, and finishing and polishing
procedures. At low speeds, tactile sensation is a better and
there is generally less chance for overheating cut surfaces.
2- Medium or intermediate speeds: (12,000 – 200,000 rpm).
3- High or ultra-high speeds: (above 200,000 rpm). Used for
tooth preparation and removing old restorations.
* Most useful instruments are rotated at either low or high
speed.
Rotary Cutting Instruments
The individual instruments intended for use with dental
handpieces are manufactured in hundreds of sizes, shapes, and types.
This variation is in part resulted from the need for specialized
designs for particular clinical applications or to fit particular
handpieces, but much of the variation also resulted from individual
preferences on the part of dentists.
In spite of the great variation that exists among rotary cutting
instruments (Burs), they have certain design features in common.
Each instrument consists of three parts: shank, neck, and head.