title: Effects of Nd: YAG laser irradiation on the root canal wall dentin of human teeth: a SEM study.
abstract: The purpose of this study was to observe the morphological and histological changes on the root canal walls after Nd:YAG laser application. Twenty vital, recently extracted single-rooted human teeth were used for this study. Root canals were cleaned and shaped by a conventional step-back technique--by means of k files up to a 20 k-file type at working length--and subsequently shaped by Ni-Ti root-canal rotary instrumentation up to 30/06 and irrigated with 2.5% hypochlorite solution. Ten teeth (control group) were left unlased, while the other ten teeth were irradiated with Nd:YAG laser by means of a 320 microns fibre inserted in the root canal at 1 mm from the apex with a power of 1.5 Watt and a frequency of 15 pps for five seconds in retraction with rotating movements. The control specimen showed debris and smear layer on the root canal surface obscuring the dentin tubules. The root canal walls irradiated with Nd:YAG laser showed a clear glazed surface, some open dentinal tubules and some surface craters with cracks. Such results confirm that smear layer and debris are removable with Nd:YAG laser, however clearing all root canal walls is still difficult and, if the energy level and duration of application are inadequate, a certain degree of thermal damage and morphological changes in dentin structure are observable.
authors.affiliation: Department of Biomedical Sciences, University of Siena, Italy. V.Kaitsas@tiscalinet.it
authors.forename: V
authors.initials: V
authors.lastname: Kaitsas
authors.forename: A
authors.initials: A
authors.lastname: Signore
authors.forename: L
authors.initials: L
authors.lastname: Fonzi
authors.forename: S
authors.initials: S
authors.lastname: Benedicenti
authors.forename: M
authors.initials: M
authors.lastname: Barone
mesh_terms: D000538:Aluminum Silicates; D000891:Anti-Infective Agents, Local / Q000627:therapeutic use; D003460:Crystallization; D003722:Dental Alloys; D003786:Dental Pulp Cavity / Q000528:radiation effects* / Q000648:ultrastructure; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure; D005336:Fiber Optic Technology / Q000295:instrumentation; D006801:Humans; D053685:Laser Therapy; D008855:Microscopy, Electron, Scanning; D009354:Neodymium; D009532:Nickel; D009804:Odontoblasts / Q000528:radiation effects / Q000648:ultrastructure; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D012399:Rotation; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D014025:Titanium; D015019:Yttrium
chemical_list: D000538:Aluminum Silicates; D000891:Anti-Infective Agents, Local; D003722:Dental Alloys; D012388:Root Canal Irrigants; C040654:titanium nickelide; D009354:Neodymium; D015019:Yttrium; D009532:Nickel; D014025:Titanium; D012973:Sodium Hypochlorite