Safety of Dental Lasers to the Eye : Irradiation under a Microscope and/or Eye Protectors

Abstract

Today, the dental microscope is recognized as one of the most useful tools for endodontic treatment, while lasers have been used for various purposes in dentistry. Laser irradiation under the dental microscope might enable more delicate endodontic procedures, however, the safety of using a laser under the dental microscope has not been sufficiently investigated. This study investigated the safety of laser use under the dental microscope. Nd:YAG laser, Er:YAG laser, and diode laser were irradiated at a power meter through laser eye protectors or a microscope, and transmitted laser energy was measured with the power meter. Laser irradiation (200mJ,10pps) was performed with an optical fiber or a contact tip (diameter=400μm) for 10sec. In the control experiment, three lasers were irradiated directly or through the eye protectors at the power meter positioned at a distance of 5cm from the fiber tip or the contact tip. In the main experiment, the fiber tip or the contact tip was positioned at a distance of 5cm from the objective lens surface of the microscope. The power meter was placed behind the eyepieces. Matched eye protectors for each laser were placed in front of the objective lens or between the eyepieces and the power meter. Laser energy transmitted through the microscope with or without the eye protectors was measured with the power meter. In each experiment, permeable energies were measured three times. The results obtained were as follows: 1. No transmitted laser energy was detected when matched eye protectors were used. 2. Mismatched eye protectors did not effectively shut out laser energy, especially for Nd:YAG and diode lasers. 3. Little or no transmitted laser energy was detected through the microscope even when no eye protectors were used. It was concluded that lasers could be used safely under the dental microscope. However, wearing matched eye protectors is indispensable to protect the eyes against accidental exposure to laser.