title: Thermal ablation of FEL irradiation using gypsum as an indicator.
abstract: Thermal effects produced in a laser-irradiated sample were studied by micro-X-ray diffraction and micro-Fourier transform infrared spectroscopy (FTIR). Gypsum, transformed into bassanite at 124 degrees C and into anhydrite at 147 degrees C, was used as a thermal indicator. Pit formation by a wavelength-tunable free electron laser (FEL) irradiation on the gypsum pellet maximized at a wavelength of 3.0 microm, 2 mJ/shot, and pits were not detected in those irradiated at 2.6 or 3.8 microm compared with the maximum at 3.0 microm and diminished at 2.0 or 4.0 microm in the human tooth case. Micro-X-ray diffraction and micro-FTIR did not reveal any appreciable bassanite or anhydrite in the irradiated regions. From the laser ablation viewpoint, these results allow the FEL ablation to be considered as plasma or evaporative ones. This study indicated that the micro-pulse of laser was effective to prevent thermal damages of laser irradiation.
authors.affiliation: Department of Anatomy, Nihon University School of Dentistry, Matsudo, Chiba, 271-8587, Japan. sakae.toshiro@nihon-u.ac.jp
authors.forename: Toshiro
authors.initials: T
authors.lastname: Sakae
authors.forename: Yukie
authors.initials: Y
authors.lastname: Sato
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Numata
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Suwa
authors.forename: Tohru
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Suzuki
authors.forename: Takao
authors.initials: T
authors.lastname: Kuwada
authors.forename: Ken
authors.initials: K
authors.lastname: Hayakawa
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hayakawa
authors.forename: Toshinari
authors.initials: T
authors.lastname: Tanaka
authors.forename: Isamu
authors.initials: I
authors.lastname: Sato
mesh_terms: D002133:Calcium Sulfate; D003737:Dental Cavity Preparation / Q000295:instrumentation*; D003743:Dental Enamel / Q000528:radiation effects*; D006801:Humans; D066298:In Vitro Techniques; D007834:Lasers; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D002133:Calcium Sulfate