Study on Use of Blue-violet Laser Diode Module as Dental/Oral Surgical Device

Laser equipment is capable of performing ablation and incision while providing hemostasis, and is widely used in intraoral surgery where bleeding can often occur(1). One of the oldest types of laser equipment is CO2 laser. The wavelength of CO2 laser (10.6 μm) is strongly absorbed by water, which means that CO2 laser is suitable for efficient ablation and incision of soft tissues that contain large amounts of water. Therefore, CO2 lasers are widely used for the treatment of inflamed areas of the body. Laser diodes began to be considered as tools for surgical treatment of soft tissues only in the 1990s when technologies for high power laser diodes were established(2). Nowadays, AlGaAs and InGaAs laser diodes are the most widely used laser diodes. Their wavelengths (810-980 nm) are within the ranges called “treatment window” or “diagnostic window”(3) and are not absorbed easily by any substances contained in the human body. Therefore, AlGaAs and InGaAs lasers can penetrate deeply into tissues. This characteristic of these laser lights to penetrate deep into tissues makes them very effective in hemostasis by forming a thick thermally coagulated layer. In addition to the coagulation effect, these lasers are used to perform ablation and incision by contacting the tip of its output fiber to the tissue(4). Moreover, laser diodes can be made smaller compared to CO2 lasers, which is an advantage in clinical applications. The commercialization of GaN blue-violet laser diode in 1999 was a significant advancement in the recent history of laser diodes. GaN blue-violet laser diode’s light output (405 nm wavelength) interacts with the substances in the living body in such a way that it is absorbed greatly by hemoglobin, and its absorption by melanin is greater by more than one order of magnitude than in the case of near infrared light(5). Hemoglobin transports oxygen in blood. Large quantities of hemoglobin are found in intraoral tissues where there are many capillaries. Large quantities of melanin also exist on gum tissue surfaces. Therefore, the authors are researching blue-violet laser diode’s application into oral surgeries(6), and also its germicidal effect against periodontal disease-causing bacteria as well as its teeth whitening capability. This research is motivated by the facts that bacteria causing periodontal diseases strongly absorb short-wavelength visible light(7) and that there are teeth whitening agents that strongly absorbs shortwavelength visible light(8). This paper covers the results of the following three application studies on blue-violet laser diodes: (1) ablation and incision of soft body tissues, (2) sterilization of periodontal disease-causing bacteria, and (3) teeth whitening.