The operation of Dental Laser is different than the conventional procedure and its development in the field of dentistry continues to expand enabling fast and accurate treatment. This post gives a detailed explanation of the meaning of Dental Laser, types of Dental Laser, working mechanism, applications, advantages and disadvantages.
What is Dental Laser
To understand the meaning of Dental Laser, let us get the basic picture of “Laser”. Light Amplification by Stimulated Emission of Radiation, most commonly known as LASER is essentially a light but it is different from normal light in many ways. One of the most important difference is the wavelength. Visible light is made of multiple wavelength and it is not coherent. Whereas Laser is made of single wavelength and is coherent.
Fig. 1 – Introduction to Dental Laser
First functioning Laser was built by Theodore Maimane, at the Hughes Research Laboratories in Malibu, CA. It was built by using a combination of Helium and Neon. The Ruby Laser in 1963 was the first Laser to be used in the field of medicine. It was used to coagulate retinal lesions.
Laser technology used in Dentistry for Dental treatment is called Dental Laser. Dental Laser is basically used in the treatment of Dental Caries (Tooth Decay), Teeth brightening, hard and delicate Tissue removal etc. When Laser is used for surgical and dental procedures, the Laser acts as a cutting instrument or it acts as a vaporizer. Laser used for teeth-whitening procedures, acts as a heat source and enhances the effect of bleaching agents. The choice of Dental Laser may cause less pain, reduce anxiety, minimize bleeding and swelling and preserve healthier tooth.
Different procedures in dentistry require different wavelengths of Lasers as each wavelength has specific thermal output. The Dental Laser is identified by the acronym that are associated with how the laser light is produced. They include Diode, Nd: YAP, Er: YAG, or CO2 as shown in the Fig. 2 below.
Fig. 2 – Dental Laser Wavelengths on Electromagnetic Spectrum
Types of Dental Laser
Dental Lasers are classified broadly into two types. They are:
- Application of Dental Laser on Soft Tissue
- Application of Dental Laser on Hard Tissue
Application of Dental Laser on Soft Tissue
The center of the tooth which contains nerves, blood vessels and connective tissue is termed as Soft Tissue and the Dental Laser used to treat Soft Tissue are
- CO2 Laser (Carbon dioxide Laser
- Nd: YAG Laser (Neodymium Yttrium Aluminum Garnet Laser)
CO2 Laser (Carbon dioxide Laser)
The CO2 Laser has high affinity towards water. This result rapid removal of soft tissue. Also results in hemostasis with a hallow depth of penetration. Carbon oxide laser has the highest absorbance among all the laser but has undesired destructive property on Hard Tissues.
Nd: YAG (Neodymium Yttrium Aluminum Garnet Laser)
The Nd: YAG is highly absorbed by the pigmented tissue. This makes it very effective surgical laser. It is effective in cutting and coagulating oral Soft Tissues and produces good hemostasis.
Application of Dental Laser on Hard Tissue
Specific Dental Lasers are used to treat Hard Tissues such as Enamel, Dentin and Cementum. The tooth has a hard outer covering called Enamel and below this is Dentin Layer. The covering of roots of a tooth is called as Cementum. Lasers that are used in the treatment of Hard Tissues include:
- ER YAG Laser (Erbium Yttrium Aluminum Garnet)
- Excimer Laser
ER YAG (Erbium Yttrium Aluminum Garnet)
The Erbium Lasers have two wavelengths, Er: YAG (Yttrium Aluminum Garnet) and Er: YSGG (Yttrium Scandium Gallium Garnet) Lasers . They have a high affinity for Hydroxyapatite and has the highest absorption of water. Thus, it is the best choice for treating Dental Hard Tissues. Erbium Lasers can also be used for Soft Tissue Ablation, due to the presence high percentage of water in oral Soft Tissues.
Excimer Lasers are used in the treatment of Hard Tissues. Excimer Lasers are used to remove residual organic tissue from the canals. This type of Dental Laser is used for the treatment of Dental Root Canals.
Fig. 3 – Classification of Dental Laser
How does Dental Laser Work
Laser is a monochromatic light with a single wavelength. They are the energy source, and includes two or more mirrors. These mirrors form an optical cavity or a resonator. A flash lamp strobe device or electrical current or electrical coil is used to create amplification by a pumping action. The energy pumped into an Active medium placed in an Optical Resonator, produces a spontaneous emission of Photons. Amplification by stimulated emission takes place because of the Photons that are reflected back and forth through the medium. This occurs due to the highly reflective surface of the Optical Resonator and also this process takes place prior to their exit through the output coupler.
In Dental Lasers, the laser light is delivered to the target tissue through either a fiber optic cable, hollow waveguide, or articulated arm. The wavelength and other properties of the Laser depends on the composition of Active medium (Laser Medium). The Active medium can be a gas or a solid-state semiconductor or a crystal.
Four different interactions can be elicited by the Laser when it comes in contact with a target tissue. They are Reflection, Transmission, Absorption and scattering. The desirable action on a target tissue is mostly absorption.
When a Laser is absorbed, the temperature is elevated. This produces photo chemical effects. The effects depend on the water content of the tissues. When a temperature of 100°C is reached, vaporization of the water within the tissue begins. This process is called Ablation. At temperatures below 100°C, but above 60°C, proteins begin to denature. But vaporization of the underlying tissue does not occur. But at temperatures above 200°C, undesirable effect called carbonization occurs. When this occurs, the tissue is dehydrated and then burned.
For absorption to occur, an absorber of light, called chromophores is required. These have a certain affinity for specific wavelengths of light. The primary chromophores in the soft tissue within the oral cavity are Melanin, Water and hemoglobin. In Dental Hard Tissues, Water and Hydroxyapatite are the absorbers. The absorption coefficients of the primary tissue components vary for different Lasers. This makes laser selection dependent on procedure.
For example: Let us consider a decayed tooth treatment with Laser. The decayed tooth area contains more water molecules than rest of the tooth and when Laser is directed on this area, the water molecules are heated rapidly and pressure increases and the decayed tooth area “explodes” making a popping sound. Laser is capable of killing the bacteria and thus the tooth surface area becomes sterile and clinician can further decide on the treatment options for this area. Fig. 4 (a) shows the production of Laser, (b) shows a decayed tooth and (c) shows representation of ‘explosion’ of decayed tooth.
Fig. 4 – Representation of Dental Laser on Tooth
Applications of Dental Laser
The applications include:
- Pain treatment.
- Root Canal Treatment.
- Contouring gums and Gum diseases.
- Impaction – for exposing tooth.
- Teeth Whitening.
- Removing benign oral tumors.
Advantages of Dental Laser
The advantages are:
- It is very effective in treating gum diseases.
- It can be used for minimally invasive procedures.
- It allows quick wound healing.
- Can be used on patients with pacemaker.
- Can reduce anxiety in patients.
- Minimize bleeding and swelling.
- Can preserve more amount of healthy tooth structure during cavity removal.
Disadvantages of Dental Laser
The disadvantages include:
- Dental Lasers cannot be used on fillings.
- Lasers can’t be used in many commonly performed dental procedures like proximal fillings, removal of old crown, for big cavities.
- Traditional ways may be needed to shape the filling, polish the filling, adjust the bite even when if Dental Laser is used.
- Anesthesia may still be needed.
- Laser treatment is expensive.