ROTARY CUTTING INSTRUMENTS

Dr.linda Maher

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

ROTARY CUTTING INSTRUMENTS

• the rotary cutting instruments are classified in to :

1. Hand pieces: these are power devices.

2. Burs: these are the cutting tools.

• 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.

HANDPIECE

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 micromotor (MICROMOTOR HANDPIECE)

TYPES OF HAND PIECE:

1.slow speed handpiece

2.high 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)

• Has two shapes:• 1-straight handpiece,this is difficult to use in

the mouth and is therefore restricted to extra oral use, such as laboratory work .

• 2-contra-angle handpiece is used intra orally for the removal of caries, polishing and finishing

SLOW SPEED HANDPIECE

• It is one piece and contra angled • This design helps to stabilize the hand piece and

improve access and visibility while it is in use.

• Operated by: compressed air ( air-turbine or Airotor.

handpiece)

• Speed: 250 000–500 000 rpm and

• It is used for: cutting through enamel and dentin and removing

previous restorations.

HIGH SPEED HANDPIECE

. 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.

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

DEDNTAL BURS

• 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.

1- cavity preparation burs are :

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

Types of dental burs:

• 2- finishing & polishing burs:

Rubber cup and coated discs

THANK YOU