Quality Resource Guide –

Lasers in Dentistry 4th Edition

www.metdental.com

Page 4

Features of Dental Lasers

hotonic

energy

can

emanate

from

dental lasers in two inherent ways: as

a continuous wave; and in free-running

pulses.

Continuous wave

means that the laser energy

is emitted as long as the laser is activated. This

produces constant tissue interaction. Some Carbon

dioxide, argon and diode lasers operate in this

manner. There is an additional modification of

the continuous wave lasers, called gated. Gating

is accomplished by mechanically or electronically

closing the opening of the mirror within the laser

chamber. Several diode and carbon dioxide lasers

offer very short pulse durations, produced by

electronic controls. These short pulses are used to

minimize some of the undesirable residual thermal

effects that can be a direct result of continuous

photon emission.

Free running pulse

lasers only produce

very short bursts of energy. Nd:YAG, Nd:YAP,

Er, Cr:YSGG, Er:YAG, and the 9300 nm Carbon

Dioxide devices

operate

in this

mode,

and

provide large packets of power for efficiency during

a procedure. The minimum laser “on” time allows a

long thermal relaxation time for the target tissue for

good heat dissipation.

A short pulse duration can be a clinical advantage

since it allows for higher power during the pulse,

increasing efficiency. However, a short pulse (or

laser ‘on’ time) should be accompanied by a

correspondingly longer ‘off’ time, to allow the tissue

to cool. This technique produces a low average

power for the procedure, in accordance with the

above mentioned fundamental of laser-tissue

interaction. A number of the newer available dental

lasers, whether continuous/gated or free-running

pulse devices, offer very small pulse durations

(measured in micro-seconds). This is especially

important for surgery on both fragile soft tissue and

any hard tissue to minimize harmful thermal effects.

Conversely, since achieving hemostasis ideally

involves sustained heat penetrating into tissue, a

pulse that is too short may cause difficulty during

procedures on highly vascularized tissue.

Some instruments use small, flexible glass fibers

to deliver laser energy (Figure 3), while others

use more rigid, tube-like devices (Figure 4). The

shorter wavelengths have small, flexible glass fiber

optic delivery systems, with bare fibers that usually

contact the target tissue. The technical challenges

of conducting the longer Erbium and Carbon

Dioxide wavelengths are demanding, and some

manufacturers have chosen to use semi-flexible

hollow wave-guides or rigid sectional articulated

arms to deliver the laser energy to the surgical

site. Some of these systems use additional small

quartz or sapphire tips, which attach to the operating

handpiece; other systems simply are used out of

contact with the tissue. In addition, the Erbium family

and the 9300nm Carbon Dioxide

lasers use a water

spray for hard-tissue procedures.

Laser Safety

here are numerous safety regulations

that are necessary for the operation of a

dental laser.

23,24

These include:

1. The presence of a designated

safety officer.

This person is the “keeper of

the key,” which allows only authorized personnel

to have access to the laser instrument. The safety

officer also must maintain a safe and protected

surgical suite, and be familiar with the operator’s

manual and manufacturer’s recommendations for

maintenance. Furthermore, this person should

oversee the inventory of supplies for laser use as

well as supervise staff education and training.

2. Government

specified

controls

on the instrument.

The Food and Drug

Administration through its Center for Devices and

Radiologic Health, sets standards that specify

certain safety features that must be installed on

each laser. Some examples are a key-lock switch,

an emergency stop button, interlocks, laser

emission indicator, and a guarded footswitch.

The use of wavelength specific

protective glasses for the surgical

team, the patient and any observer.

The

eyewear must be designed with side shields, and

must minimally attenuate the laser beam to one-

ten thousandth of its output power. The glasses

must be clearly marked with the wavelength for

which they offer the protection.

4. An operatory with limited access

and minimal reflective surfaces.

A sign

with specific information is to be posted outside of

the laser beam’s hazard zone. The hazard zone

is the clear area where eye and other protective

measures are essential. Each laser manual has

the information to determine the hazard zone.

High-volume evacuation of the

laser plume.

The laser plume may contain

many biohazards, such as viruses, blood

by-products, and metallic fumes, as well as odors.

Adherence to infection control

standards for surgical devices.

The

standard of care for surgical devices is steam

sterilization for small flexible optic fibers,

handpieces, and tips. The remainder of the laser

and its attached delivery system should receive a

surface disinfectant protocol.

Figure 3

A small diameter glass fiber placed in the

periodontal pocket.

An articulated arm that delivers laser energy

coupled to a handpiece (not shown).

Figure 4