Power Driven Scalers (PDS)

Power Driven Scalers

• Power Driven Scalers (PDS) are also known as ultrasonic scalers
• Instrumentation/debridement (manual) was the only method for calculus removal until ultrasonic devices were introduced in about 1950
• PDS is the umbrella term for all power-driven scalers
• Types routinely seen in general practice:
  • Piezoelectric
  • Magnetostrictive
  • Sonic

What is a Power Driven Scaler

• Removes plaque and calculus from the tooth surface through mechanical action
• Converts high-frequency electrical energy (ultrasonic) or air pressure (sonic) into high-frequency sound waves
• Energy at the tips helps fracture calculus from the tooth surface
• Aids in cleansing pathogens from within the periodontal pocket

Why Use Power Driven Scalers

• Provides optimal treatment outcomes
• Allows better access to complex areas
• Disturbs plaque biofilm
• Reduces operator fatigue
• Optimizes appointment time
• Reduces patient discomfort

Modes of Action of PDS

• Cavitation: Formation of pulsating bubbles powered by an ultrasonic field
  • Ultrasound waves pass through water, pushing molecules closer and pulling them apart
  • High sound wave movement causes small bubbles to violently expand and collapse
  • Energy is released as a shock wave, heat, and/or abrupt hydraulic pressure changes
  • Though quickly dissipated, the coolant creates thousands of collapsing bubbles
• Acoustic Micro Streaming: Energy released around ultrasonic devices
  • Involves the movement of small water currents
  • Micro streaming occurs near oscillating objects, such as cavitation bubbles or the scaler tip
  • Currents produce shear forces strong enough to break up bacteria clumps but not cell walls
  • Shown to disrupt biofilm and break up bacteria colonies
• Lavage
• Mechanical

Advantages of Power Driven Scalers

• Easier removal of heavy deposits/stain
• Reduction of tissue trauma
• Lavage and cavitational effect
• Acoustic disturbances
• Better furcation tip access, causing less damage
• Less tissue distension
• Cementum conservation because the periodontal ligament is attached
• Time management
• No sharpening needed
• Reduces operator fatigue, lowering the likelihood of carpal tunnel syndrome/repetitive strain
• Patient preference

Disadvantages of Power Driven Scalers

• Reduced visibility due to water accumulation
• Patients may have difficulty breathing through their nose
• Tooth sensitivity during the procedure
• Reduced tactile sense due to vibrations
• Mirror use is limited because of water spray
• Risk of aerosol formation spreading infection up to 3 meters
• Noise requires removal of hearing aids and can damage clinician hearing
• Compromised procedure without nursing assistance can increase the risk of injury
• Running out of water
• Patients may dislike the procedure
• Clinicians may deskill and rely on power driven scalers
• Cannot be used on newly erupted teeth due to immature enamel

Clinician Considerations for PDS Use

• Oral control
• Contraindications of use
• Adaptation - Tip anatomy
• Recognizing a failing tip
• Maintenance

Contraindications to PDS Use

• Pacemaker
• High susceptibility to infections
• Respiratory risk
• Difficulty in swallowing
• Prone to gagging
• Sensitivity
• Untreated cleft palate
• Areas of demineralization due to enamel being decalcified
• Around crowns/implants

Frequency

• The number of times a scaler tip vibrates per second, measured in cycles per second (Hz)
• Frequency does not change for scaler when power is adjusted, just amplitude changes
• Higher frequency means rapid vibrations, increasing efficiency of calculus removal

Amplitude

• Amplitude is the distance the scaler tip moves back and forth during one vibration cycle
• Higher amplitude means longer strokes, which increases the power of the scaler
• Amplitude is altered depending on deposits present
• Low amplitude (smaller movement) needed for plaque biofilm
• High amplitude (larger movements) needed for calculus

Ultrasonic vs Sonic Frequency

• 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

• Active Tip Area
• Points of Energy Dispersion
  • Point is the most powerful
  • Concave Face
  • Convex Back
  • Lateral Surfaces are the least powerful

Recognizing a Failing Tip

• Tip extends beyond the blue line which means optimum efficiency for scaling away
• 25% Efficiency Loss when the tip touches the blue line, it’s time to reorder
• A 50% Efficiency loss happens when the tip touches the red line, so discard the tip

What To Do If a Tip Cannot be Found

• A fractured tip is a serious concern.
• Considerations:
  • It could be wedged in a periodontal pocket
  • It could have been swallowed or spat out
  • It could have been inhaled
• If you cannot find it, the patient will have to undergo a chest x-ray

Maintenance Checks

• Always check tips for wear before every use
• Ensure all equipment is working correctly
• Ensure an adequate water supply.
• Inserts not bent

Piezon Maintenance Checks

• Piezo tips will disappear down the drain, so avoid it
• Ensure the tip is tightened correctly

Care of Insert and Handpiece

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

Insert Cleaning

• Ultrasonic bath
• Water bath
  • 15 minutes OR
• pH neutral cleaning solution
  • 15 minutes
• Follow the manufacturer's instructions for concentration rates and contact times

Insert Malfunctions

• Overheating, caused by:
  • Improperly adjusted water flow
  • Not filling handpiece with water before inserting the tip
  • Using an unserviceable insert
  • Issues with the water source
• Clogged water with no or low water flow: clear clog with Finger Spreader
• Leaking water: Worn O ring

Comparison of Piezon vs Magnetostrictive Scalers

• Magnetostrictive
  • 20-40 kHz
  • Elliptical stroke pattern
  • Metal rod or stack of metal sheets
  • All surfaces active
• Piezoelectric
  • 29-50 kHz
  • Linear stroke pattern
  • Crystals activated by ceramic handpiece
  • Only active on lateral sides

Final Safety Check

• Always remove and/or make safe the Power Driven Scaler between use.
• Even if you are going to use it again in a few minutes
• Never leave the tip pointing upwards.
• Never leave it uncovered. This prevents a needle-stick accident.