Theory - Ultrasonic Instrumentation

Objectives of Periodontal Debridement

- Disruption and removal of subgingival biofilm
- Removal of plaque retentive factors
- Conservation of tooth structure
- Resolution of inflammation

Ultrasonic Instrumentation Mechanisms of Action

Mechanical
Irrigation
Cavitation
Acoustic microstreaming

Mechanical

Primary action

Irrigation

irrigant (usually water) is used with ultrasonic instruments to counteract any frictional heat generated by oscillating tip moving against tooth surface

Cavitation

Formation and explosive collapse of microscopic bubbles in a flowing liquid resulting from forces acting on liquid

acoustic microstreaming

swirling effect produced within the pocket by stream of fluid flowing over vibrating tip

occurs near any object in oscillatory motion in liquid

Magnetostrictive Components

**Cavitron is considered this

Insert
Handpiece
Base unit
Foot switch

Piezoelectric Components

Tip
Handpiece
Base unit
Foot switch

What is oscillation?

Forward and backward movement

The high-frequency oscillating action of the blunt tip contacting the deposit (biofilm or calculus) mechanically disrupts or fractures the deposit.

The conversion of electrical current into high-frequency mechanical vibrations is attained by what?

a transducer that is either magnetostrictive or piezoelectric in nature.

distinguishing components of a magnetostrictive ultrasonic scaler

insert and handpiece.

What is the insert in a magnetostrictive ultrasonic scaler composed of?

a stack of thin nickel strips soldered together at the ends and attached by a connecting body to a tip.

Hand piece of magnetostrictive ultrasonic scaler

The handpiece surrounds the nickel stack of the insert with copper wire, which generates an alternating magnetic field upon application of electrical current.

A piezoelectric ultrasonic scaler is differentiated by what?

a tip which screws onto the handpiece using a torque wrench.

Ultrasonic Operational Variables

Operating frequency
Power input
Water flow rate
Tip diameter
Tip shape

What is the operating frequency of the unit?

the number of complete back-and-forth cycles (strokes) the oscillating tip completes per second, measured in kilohertz.

T/F: the amount of electrical power input to the transducer is adjustable

TRUE

it is adjustable by manipulating the power setting of the unit.

The power setting used influences what?

the range of movement, or stroke length

What angulation do you use with ultrasonic scaler?

0 - 15 degree angulation

Stroke length is measured as what?

the displacement amplitude, meaning how far the tip is displaced from a position of zero movement.

Why is an adequate supply of water to the tip needed?

to minimize the production of frictional heat and to generate a lavage and the mechanisms of cavitation and acoustic microstreaming.

The diameter and shape of the tip used have a direct impact on what?

both the mechanical and biophysical (cavitation/microstreaming) mechanisms of action

Function produced by ultrasonic scaler is a function of

Efficiency of mechanical mechanism of action

Amount of cavitation and microstreaming activity

Factors influencing appropriate level of acoustic power

Displacement amplitude
Tip diameter
Tip shape

The net force exerted by the oscillating tip directly correlates to what?

the tip's mass (diameter) and to the distance the tip moves (displacement amplitude).

The efficacy and extent of biofilm disruption is relative to what?

the amount of cavitational and acoustic microstreaming occurring in the water surrounding the oscillating tip.

In order to accomplish efficient deposit removal without overinstrumentation of the root surface, it essential for the clinician to do what?

operate the ultrasonic scaler at the minimum effective acoustic power level.

Key features of ultrasonic tips

Diameter ( width)

Shape ( cross-section, circular or rectangular)

Geometry( number of places crossed by the shank)

Profile ( number of bends in active area)

When to replace tips

Manufacturers suggest replacement when 2mm of tip length is lost

What tips do you use on implants?

Carbon fiber or plastic tips are safe for use on the smooth titanium portion of implants

Types of ultrasonic tips

Straight
Contrangled
Periodontal

Straight tips

Slightly curved in only one direction
Universal use

Contrangled Tips

Paired instruments used in specific areas

Periodontal Tips

Thin straight
Designed for subgingival areas
Slimline

Thicker blue and green tips

an be used on higher settings and typically used for moderate to heavy calculus

Purple tip

thinner, can be used for light calc or biofilm disruption (good for gingivitis pts) and should be used on lower power

Adaptation for ultrasonic

Vertical
Horizontal
Oblique

What is the primary adaptation technique used during ultrasonic debridement?

vertical orientation

Horizontal adaptation

positions the active area of the tip perpendicular to the long axis of the tooth.

Oblique adaptation

the orientation required to remove deposits with a bladed instrument

Instrumentation and advancement of ultrasonic

With channeling, tip is advanced to base of pocket using stroke pattern indicated

Grasp of ultrasonic

Correct placement of grasp is determined by first balancing handpiece between thumb and forefinger

Sequence of Ultrasonic

Work by sextant

Why is it good to work by sextant with ultrasonic?

- More efficient
- Reduces frequency of changing tip
- Requires fewer changes in operation position

Clinical preparation for ultrasonic

Flush water lines 60 seconds
Fill handpiece with water
Insert appropriate tip
Adjust water supply to a fine mist
Preprocedural rinse
Standard precautions
Communicate with your patient

Tip adaptation

- Parallel to tooth surface
- Tip angulation near zero degrees
- Little to no lateral pressure
- Keep tip moving at ALL times

Medical Considerations

- Communicable Disease

- Immunocompromised patients (Kidney disease, chemo tx, organ transplant)

- Respiratory (COPD, emphysema, uncontrolled asthma, cystic fibrosis)

- Dysphagia or those who gag easily (Risks for aspiration pneumonia &
MS, Parkinson's, Muscular Dystrophy, post-stroke)

- Pacemakers (No cavitron if unshielded)