Laser radiation bracket debonding

Abstract

ABSTRACT Ceramic brackets are an aesthetic substitute for conventional stainless steel bracketsin orthodontic patients. However, ceramic brackets are more brittle and have higher bond strengths, which can lead to bracket breakage and enamel damage during classical type of debonding. This study examined the possibility of laser radiation ceramic brackets removing as well as the possible damage of a surface structure of hard dental tissue after this procedure. Two types of lasers were used for the experiments – a laser diode LIMO HLU20F400 generating a wavelength of 808 nm with the maximum output power 20W at the end of the fiber (core diameter 400 µm, numerical aperture 0.22). As a second source, a diode-pumped Tm:YAP laser system generating a wavelength of 1.9 µm, with up to 3.8 W maximum output power was chosen. For the investigation, extracted incisors with ceramic brackets were used. In both cases, laser radiation was applied for 0.5 minute at a maximum power of 1 W. Temperature changes of the irradiat ed tissue was registered by camera Electrophysics PV320. After the interaction experiment, the photo-documentation was prepared by the stereomicroscope Nikon SMZ 2T, Japan. The surface tissue analysis was processed in “low vacuum” (30 Pa) regime without desiccation. This technique was used to record back–scattered electron images. Selecting the appr opriate laser, resin, and bracket combination can minimize risks of enamel degradation and make debonding more safe. Keywords: dentistry, orthodontics, ceramic bracket debonding, diode laser, Tm:YAP laser