Mechanical Scalers

Question 1

What are the two types of mechanical scalers and their operating frequencies?

Answer 1

• ultrasonic: operating at 20-30kHz
• Sonic or air: operating between 5-10kHz
  Both types of instrument use water at the working tip to cool the working tip and flush debris away from the site of operation

Question 2

How does a sonic scaler operate?

Answer 2

• operated by air line which is usually connected to the air turbine. The air is passed over a metal reed in the handpiece which vibrates in a similar manner to that of a wind instrument

Question 3

How does an ultrasonic operate?

Answer 3

• powered by electric current, operate at a frequency of between 20,000 and 30,000 vibrations per second
• far more patient friendly

Question 4

What are the types of ultrasonic and how do they work?

Answer 4

Magnetostrictive: a stack of ferromagnetic metal is acted upon, by electrical windings in the hand piece, which produce an alternating magnetic flux
- when the stack is magnetised it contracts and this movement is transferred to the working tip
Piezoelectric: small currents are used to alter the dimensions of quartz crystals which produces the vibration

Question 5

What are the modes of action of an ultrasonic?

Answer 5

• mechanical abrading action: where the mixture of back, forth and circulatory movements of the working tip mechanically abrades and chips away at the calculus deposits on the tooth surface
• cavitational effects: due to high energy output, water contains air bubbles which are expanded by energy at working tip, causing them to implode, thus releasing shock waves. Shock waves remove calculus and plaque, air bubbles release oxygen and kill anaerobic bacteria
• acoustic streaming: vigorous movements of water around tip to remove some of the tooth surface deposits and disrupt plaque colonies

Question 6

What are the indications for the use of mechanical scalers?

Answer 6

• supra/sub gingival deposits
• pre and post RSD
• cavitational effect only
• stain removal
• removal of excess cement/amalgam ledges

Question 7

What potential hazards are associated with the use of ultrasonics?

Answer 7

• porcelain crowns can be fractured and cement lutes broken by the energy given out at the working tips
• hypersensitivity
• decalcification
• implants
• pacemakers - can contribute to temporary increase of pace rate