title: Histological and SEM analysis of root cementum following irradiation with Er:YAG and CO2 lasers.
abstract: Recently, the Er:YAG and CO(2) lasers have been applied in periodontal therapy. However, the characteristics of laser-irradiated root cementum have not been fully analyzed. The aim of this study was to precisely analyze the alterations of root cementum treated with the Er:YAG and the CO(2) lasers, using non-decalcified thin histological sections. Eleven cementum plates were prepared from extracted human teeth. Pulsed Er:YAG laser contact irradiation was performed in a line at 40 mJ/pulse (14.2 J/cm(2)/pulse) and 25 Hz (1.0 W) under water spray. Continuous CO(2) laser irradiation was performed in non-contact mode at 1.0 W, and ultrasonic instrumentation was performed as a control. The treated samples were subjected to stereomicroscopy, scanning electron microscopy (SEM), light microscopy and SEM energy dispersive X-ray spectroscopy (SEM-EDS). The Er:YAG laser-treated cementum showed minimal alteration with a whitish, slightly ablated surface, whereas CO(2) laser treatment resulted in distinct carbonization. SEM analysis revealed characteristic micro-irregularities of the Er:YAG-lased surface and the melted, resolidified appearance surrounded by major and microcracks of the CO(2)-lased surface. Histological analysis revealed minimal thermal alteration and structural degradation of the Er:YAG laser-irradiated cementum with an affected layer of approximately 20-μm thickness, which partially consisted of two distinct affected layers. The CO(2)-lased cementum revealed multiple affected layers showing different structures/staining with approximately 140 μm thickness. Er:YAG laser irradiation used with water cooling resulted in minimal cementum ablation and thermal changes with a characteristic microstructure of the superficial layer. In contrast, CO(2) laser irradiation produced severely affected distinct multiple layers accompanied by melting and carbonization.
authors.affiliation: Department of Periodontology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
authors.forename: Aslam
authors.initials: A
authors.lastname: Almehdi
authors.forename: Akira
authors.initials: A
authors.lastname: Aoki
authors.forename: Shizuko
authors.initials: S
authors.lastname: Ichinose
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Taniguchi
authors.forename: Katia M
authors.initials: KM
authors.lastname: Sasaki
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Ejiri
authors.forename: Masanori
authors.initials: M
authors.lastname: Sawabe
authors.forename: Chanthoeun
authors.initials: C
authors.lastname: Chui
authors.forename: Sayaka
authors.initials: S
authors.lastname: Katagiri
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Izumi
mesh_terms: D003739:Dental Cementum / Q000528:radiation effects* / Q000648:ultrastructure; D012534:Dental Scaling / Q000295:instrumentation; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D054020:Lasers, Gas; D053844:Lasers, Solid-State; D008855:Microscopy, Electron, Scanning; D013052:Spectrometry, X-Ray Emission; D018709:Statistics, Nonparametric; D013499:Surface Properties; D014092:Tooth Root / Q000528:radiation effects* / Q000648:ultrastructure