ROTARY CUTTING INSTRUMENTS Dr.linda Maher

ROTARY CUTTING INSTRUMENTS

A group of instruments operated with a power source and used for cutting, finishing & polishing tooth structure.

the rotary cutting instruments are classified in to :

1. Hand pieces: these are power devices.

2. Burs: these are the cutting tools.

HANDPIECE a small drill used during dental

procedures. FUNCTIONS OF HANDPIECE:

1.holds rotating instrument (bur) and transmits power to it.

2. helps to position and control the rotating instrument (bur) intra orally.

Hand pieces are operated by

1\air pressure that is supplied by a compressed air transmitted through a compressor.(AIROTOR HANDPIECE)

2\directly by an electric motor (MICROMOTOR HANDPIECE)

TYPES OF HAND PIECE:

1.slow speed handpiece

2.high speed handpiece

SLOW SPEED HANDPIECE Usually composed of two peaces Operated by: either a compressed air or directly by

an electric motor. The speed of the handpiece: ranges from 0 to 40 000 rpm.(round

per minute) The most efficient cutting is achieved

with a straight handpiece, but this is difficult to use in the mouth and is therefore restricted to extra oral use, such as laboratory work . The contra-angle handpiece is used intra orally for the removal of caries, polishing and finishing

HIGH SPEED HANDPIECE It is one piece and contra

angled Operated by: compressed air ( sometimes referred to as an air-

turbine or Airotor.) Speed: 250 000–500 000 rpm and It is used for: cutting through enamel and

dentin and removing previous restorations.

. water spray is directed at the

cutting part of the bur to keep it cool

. A fibreoptic light in the head of the

handpiece aids visibility.

CONTRA -ANGLE HANDPIECE

Description: the head of the hand piece is first angled away & then toward, the long axis of the handle.

This design helps to stabilize the hand piece and improve access and visibility while it is in use.

MICROMOTOR HANDPIECE Description: Micro motor hand pieces are

attached to an electric micro-motor

Speed: They operate at speed ranges between 12,000-200,000 RPM (round per minute).

Uses:

1.removing soft caries

2. Placing retention grooves.

retention groove

AIROTOR HANDPIECE

Description: Airotor hand pieces are connected to the air compressor.

Speed: They speed range is above 200,000 RPM (highest speed handpiece).

Uses:

1. Removing old restoration.

2. cavity preparation

3. Tooth reduction for crown preparation.

Removing old restorationTooth reduction for crown preparation

DEDNTAL BURS

A bur is a rotary cutting instrument supplied with cutting head of various shapes

parts of a dental bur:

1. Shank : is the part of the bur which fits into the handpiece.

2. Neck: the neck serves to connect the shank to the head of the bur.

3. Head: this is the working end of the bur and is available in various sizes, shapes and materials.

Burs materials: stainless steel or tungsten carbide.

Burs sizes: the number representing the bur size has been used as a code for the diameter of the head.

Burs shape: burs are available in several shapes. There shapes correspond to the function.

RETENTION OF BURS TO THE HANDPIECE:

1\ Latch grip for slow speed.

2\ Friction grip for high speed.

Shapes for cavity preparation burs are :

Round, inverted cone, pear shape, straight fissure & tapered fissure.

Shapes for finishing & polishing restorations burs:

Rubber cup and coated discs

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