essay 19 - high frequency Electro surgery, piezo surgery and lasers in oral surgery

What is high frequency Electro surgery

• also known as radio frequency surgery or diathermy. it involves the conversion of electrical energy into heat via an electrosurgical unit and conductive instruments.

• involve the use of high frequency alternating current (>/= 200 kHz) transmitted to biological tissue to achieve:

— cutting

— coagulation (hemostasis)

— devitalization (tissue destruction)

— Thermo fusion (vessel sealing)

describe the mechanism of action

1. tissue heating is crucial

• <45 degrees: reversible damage

• > 90 degrees: evaporation → desiccation or vaporisation

• >/= 200 degrees: tissue carbonization

2. requires a closed circuit:

• Older “ ground referenced” systems risked burns

• modern systems are ground isolated - current flows only through defined pathways

what are the modes of application

1. monopolar = current flows from active electrode → Patient→ return Plate

• requires attention in patients with pacemakers or metal implants

2. bipolar = current flows between two integrated electrodes in the same instrument

• advantages:

— no return plate needed

— minimal leakage current

— safer with electronic devices(ECG, EEG)

— used in neurosurgery, ENT, gynaecology and minimally invasive surgery

what are the effects on tissue

1. cutting - Continuous Current, High heat, vaporisation

2. fulguration - interrupted current, superficial charring/ coagulation

3. desiccation - electrode contact tissue, slower heating, tissue dries

What is Piezoelectric Surgery

• a minimally invasive ultrasonic bone surgery technique it is based on the piezoelectric effect; vibrations from pressure on certain crystals. it enables precise depth control and minimal iatrogenic trauma.

• first introduced in 1953 (catuna), with later applications in orthopaedics and oral surgery.

• it has advantages over traditional Rotary tools as it avoids:

— Bone overheating (>47 degrees) → necrosis

— excessive pressure and reduced tactile control

— soft tissue damage near vital structures (e.g nerves, sinus)

device components of piezoelectric surgery

• handpiece

• base unit

• foot pedal

• interchangeable inserts for specific tasks

List The key features of piezoelectric surgery

• cavitation effect

• adjustable parameters

• factors affecting performance

Describe cavitation effect

• formation of bubbles that grow in diameter, Then implode

• this enhances hemostasis → bloodless surgery

• suggested antibacterial effects by disrupting bacterial cell walls

what is adjustable parameters

• Frequency (Hz)

• power (W)

• water spray for cooling

what are the factors affecting performance - piezoelectric surgery

• Bone Density

• tip design

• hand pressure

• speed of movement

what are lasers

• light amplification by stimulated emission of radiation

• invented by Theodore Maiman in 1960 using a Ruby crystal

• it operates by delivering monochromatic, focused, coherent light

laser-laser tissue interactions depend on

• wavelength

• Pulse, Energy and duration

• tissue optical properties

what are the interaction types of lasers with targets

• Transmitted

• reflected

• Absorbed

• scattered

what are the Major effects of lasers

1. photothermal - heating → cutting, coagulation, ablation

2. Photo Mechanical - acoustic waves → tattoo, stone removal

3. photochemical - light induced chemical changes

4. Photobiostimulation - healing, anti-inflammatory effects

5. optical - diagnostics (e.g fluorescence imaging)

clinical applications of lasers

• incisions, vaporisation, coagulation, biostimulation

• surgical lasers can be:

— continuous wave

— pulsed

— Q switched (very short high energy pulses)

advantages of lasers

• hemostasis

• asepsis (non contact)

• reduced pain and edoema

• reduced risk of scarring

• Enhanced healing

• microsurgical precision

• fewer surgical instruments

the risks of lasers

• laser plume = toxic smoke, viral particles (e.g HPV) → need for high volume evacuation

• iron tissue safety requires protective measures