Biology behind Lasers in Dentistry

Questions: Biology

1. When the laser comes into contact with the biological interface what interactions occur? 

2. How are lasers used to stop and prevent gum disease from occurring?

3. How do lasers strengthen a bond between a tooth and a filling?

4. What biological effects occur when laser photons interact with tissue in gums?

Answers            

1. When a laser beam that is being used for dental purposes engages into physical contact with the biological interface one of these four types of interactions will happen. Reflection, transmission, scattering or absorption.

Reflection: One of the four interactions that occur when the laser interacts with the biological tissue of the gum is reflection. For this interaction the laser beam reflects off the tissue without penetrating the tissue itself. Although reflection does not occur often it is predominantly used when certain types of lasers (erbium) reflect off of titanium which in turn allows for easy cleaning of the gingiva found usually around implants.

 Transmission: Another interaction which occurs is transmission. In transmission the energy from the lasers pass through the first layers of tissue but doesn't fully penetrate the tissue. This interaction is used to reach areas inside the gum without having to cut the gum open.

Scattering: For this interaction when the laser reaches the tissue it will scatter in many different directions. Not frequently used only used to help biostimulative properties.

Absorption: This is the most important interaction.  When the laser comes into contact with the tissue the molecules in the tissue called chromophores absorb the photons of the laser. From there the energy that was absorbed is now converted into other forms of energy (thermal, mechanical etc.) 

2.  Gum disease is when there is an infection on the supporting tissues of the bone that holds your teeth in place ( gum). The type of laser treatment used to treat this is called periodontal laser therapy. In this type of therapy the dental laser is used to remove the inflamed gum tissue from around the tooth. Once the infected tissue is removed the root of the tooth is exposed. Now a process called root scaling can begin, first they scrape off the calculus and plaque around the root then they smooth out the root and let it heal naturally.

3. Lasers have many different applications but one of the applications it is used frequently for is to cure a filling. To cure a filling the laser is applied to the area where the tooth and the filling meet. When this happens the heat from the laser causes the filling and the tooth to weld together therefore strengthen the bond that they share.

 

4. When laser photons enter the tissue found around a tooth 4 things may occur: fluorescence, photothermal, photodisruptive, and photobiomodulation

 

Fluorescence: fluorescence will occur when the tooth is exposed to 655nm visible wavelength. They use fluorescent to diagnose and manage carious lesions

Photothermal: This happens when chromophores absorb the laser energy and heat is created. The heat generated is used to coagulate blood and incising tissue 

Photodisruptive: This is when short pulsed burst of the laser are used to interact with the water in the tissue causing thermal expansion to occur with the water in the tissue. Because of the thermal expansion in the water molecules small micro explosions occur which aids in the disrupting enamel and bony matrices without causing thermal damage

 

Photobiomodulation: Lasers ability to increase healing rates, circulation, reduce edema and minimize pain. This laser has also increased collagen, synthesis, fibroplast proliferation, increased osteogenesis and enhanced leukocyte phagocytosis. Photobiomodulation is used in dentistry to treat sickness like recurrent herpes and stomatitis.