Power Driven Scalers (PDS)

• Instrumentation/debridement (manual) was the only method for calculus removal until ultrasonic devices were introduced ~1950.
• Power Driven Scalers (PDS) is the umbrella term for all power driven scalers.
• PDS includes piezoelectric, magnetostrictive, and sonic scalers.

What is a Power Driven Scaler?

• A power driven scaler removes plaque and calculus from the tooth surface through mechanical action.
• They convert high frequency electrical energy (ultrasonic) or air pressure (sonic) into high frequency sound waves.
• The energy at the tip fractures calculus from the tooth surface.
• PDS assists in cleansing pathogens from within the periodontal pocket.

Why use PDS?

• Optimal treatment outcomes
• Better access to complex areas
• Disturbance of plaque biofilm
• Reduce operator fatigue
• Optimum use of appointment time
• Reduced patient discomfort

Modes of Action of PDS

• Cavitation effect
• Acoustic turbulence
• Lavage
• Mechanical

Cavitational Effect

• Cavitation is the formation of pulsating bubbles powered by an ultrasonic field.
• Ultrasound waves passing through water push molecules closer together and pull them apart in a split second.
• Micromillimeter-sized bubbles expand and collapse violently if the movement of sound waves is high.
• The subsequent energy is released as a shock wave, heat, and/or abrupt changes in nearby hydraulic pressures.
• Thousands/millions of bubbles produced collapse within the coolant, creating the appearance of pulsation.

Acoustic Micro Streaming

• Acoustic micro streaming is an energy released around ultrasonic devices.
• The phenomenon is characterized by the movement of small currents in the water.
• Micro streaming commonly occurs around oscillating objects such as cavitation bubbles or the scaler tip.
• The currents produce shear forces strong enough to break up clumps of bacteria but not bacterial cell walls.
• These forces can break up colonies of bacteria and disrupt biofilm.

Advantages of Power Driven Scalers

• Easier removal of heavy deposits/stain
• Reduction of tissue trauma
• Lavage
• Cavitational effect
• Acoustic disturbances
• Furcation tip access causes less damage
• Less tissue distension
• Conservation of cementum
• Time management
• No sharpening needed
• Reduces operator fatigue and therefore reduces likelihood of carpel tunnel syndrome/repetitive strain
• Patient preference

Disadvantages of Power Driven Scalers

• Reduced visibility due to water accumulation
• Patients who cannot breath through their nose
• Tooth sensitivity during procedure
• Reduced tactile sense
• Mirror use limited due to water spray
• Aerosol formation
• Noise
• Compromised procedure without nursing assistance
• Running out of water in the bottle
• Patients wearing hearing aids may have to remove them
• Patient dislikes it

Clinician considerations of PDS use

• Oral Control
• Contraindications of use
• How it works
• Adaptation – Tip anatomy
• Recognising a failing tip
• Maintenance

Contraindications to Use

• Pacemaker
• High susceptibility to infections
• Respiratory risk
• Difficulty in swallowing
• Prone to gagging
• Sensitivity
• Untreated cleft palate
• Areas of demineralisation
• Around Crows/implants?

Frequency

• Frequency refers to the number of laps per second
• Amplitude refers to the length of the stroke
• Low Power (Blue Zone): ~0.0001 in
• Med. Power: ~.001-.003 in
• High Power: ~.003-.005 in
• Movement increases with power increase

Ultrasonic vs. Sonic Scalers

• Ultrasonic powered devices operate at 18,000 to 45,000 cycles per second.
• Sonic powered devices operate at a lower frequency of 3,000 to 8,000 cycles per second.

Insert Parts

• Tip
• Connecting body
• Stack
• Finger grip (nozzle)
• O-ring seal

Tip Anatomy

• The active tip area is the portion of the instrument tip that does the work.
• The point is the most powerful, followed by the face, then back, then the lateral surfaces
• Tip geometry is defined by the number of planes that the shank of the tip crosses.

Lateral Pressure

• Use a light grip
• Guide into pocket
• No tip use

Tip wear

• Tip extends beyond the blue line: Optimum Efficiency (Scale Away)
• If the tip touches the blue line: 25% Efficiency Loss (Reorder)
• If the tip touches the red line: 50% Efficiency Loss (Discard)
• Bent or re-shaped tips should be avoided

Maintenance of Magnetostrictive PDS

• When a fractured tip occurs within the mouth it presents a serious cause of concern.
• The tip could become wedged in the periodontal pocket.
• The tip could have been swallowed, spat out, or even inhaled.
• If a fractured tip cannot be located, the patient will require a chest x-ray to identify its location.

Maintenance Checks

• Examine tips for general wear prior to EACH use.
• Ensure all equipment is in working order.
• Ensure you have enough water in the bottle
• Verify that inserts are not bent

Piezon Maintenance Checks

• Be careful or the Piezo tips will disappear down the drain, in a flash!
• Confirm the tip is tightened, and secure.

Insert and handpiece piece care

• Reprocess as soon as possible
• Remove insert from the handpiece
• Remove handpiece from the cable
• Wipe/rinse thoroughly
• Remove excess soil
• Check for signs of visible contamination

Insert cleaning

• Use an ultrasonic bath.
  • Submerge the insert in a water bath for 15 minutes or pH neutral cleaning solution for 15 minutes.
• Follow the manufacturer's instructions observing concentration rates and contact times

Insert malfunctions

• Overheating
  • Improperly adjusted water to the insert
  • Not filling the handpiece with water before inserting the tip.
  • Use of an unserviceable insert
  • Water source issues

Clogged Water

• Characterized by no or low water flow
• Clear clog with Finger spreader

Leaking Water

• A common cause of leaking water is worn O-rings

Comparison of Piezon vs Magnetostrictive

• Magnetostrictive scalers operate on a frequency of 20-40 kHz and produce an Elliptical stroke pattern.
• Piezoelectric scalers operate on a frequency of 29-50 kHz and produce a Linear stroke pattern.
• Magnetostrictive scalers’ Energy Conversion involves a metal rod or stack of metal sheets and produce power dispersion on all surfaces.
• Piezoelectric scalers’ Energy Conversion uses crystals activated by a ceramic handpiece and produce Only active on lateral sides power dispersion.

Final Safety Check

• Remove/make safe the Power Driven Scaler between uses, even if you are going to use it again in a minute.
• Never leave the tip pointing upwards/uncovered.