lasers in endodontics, facts or fictions?
Endodontics have always had a special position in conservative dentistry. If endodontics treatment fails it inevitably leads to surgery or the loss of a tooth, both of which are significant consequences for the patient.
The pathological reaction is caused by a bacterial root canal system in which certain species of bacteria thrive to produce the clinical picture of periapical periodontosis. Conventional endodontic treatment consists of cleaning the root canal by mechanical means and irrigation with antibacterial solutions. One distinct disadvantage of these solutions is that bactericidal effects are only present in the root canal. Due to the narrow diameter of the dentinal tubules and the high surface tension of liquid solutions, they can only penetrate into a small part of the canal tissue. Chemical disinfectants reach only 100µm into the adjoining root dentin. Experiments performed by Kouchi et al. show that during infection, bacteria colonize the dentinal tubules up to 1100µm from the canal lumen. This explains why bacteria in the deep dentin layers are not destroyed by chemical disinfectants.
For many years, lasers could only be used with a rigid delivery system, such as a mirror-joint. Only the development of new light-conducting materials made the application of diverse wavelengths in the root canal possible. By using a flexible RFT fiber, the radiation can be led directly into the root canal and can therefore also act in the apical third. During the past few years, several laser systems have gained widespread acceptance in endodontic therapy because LASERs have been shown to be very effective in cleaning and disinfecting the root canal lumen.
The combination of an Er,Cr:YSGG LASER and a 940nm diode LASER has the ideal properties for this application. The first one is well absorbed in water and hydroxiapatide, so that smearlayer, organc material and infected rootcanal wall dentin can be well removed showing open lateral dentinal tubles. Thie second wavelengths is scarcely absorbed by the dentin, therefore providing a sufficient depth of penetration, prerequisite to the good bactericidal effects. The crown down technique in combination with this two laser treatments will provide the highest possibility for a successful treatment.