title: Morphological study on the capability of Er:YAG laser irradiation for root canal preparation.
abstract: OBJECTIVE
  The purpose of this study was to evaluate morphologically the capability of Er:YAG laser irradiation for root canal preparation in vitro.
  
  
  BACKGROUND
  There have been no reports on root canal preparation using Er:YAG laser irradiation.
  
  
  METHODS
  Forty extracted human teeth were divided randomly into two groups of 20. Laser irradiation was performed using three different sizes of fiber tips at the two different parameters (G 1, 2 Hz and 136-184 mJ/pulse; G 2, 2 Hz and 170-230 mJ/pulse). After laser irradiation, the teeth were bisected longitudinally and observed by stereoscopy and field emission-scanning electron microscopy (FE-SEM). The time required for preparation in each group was recorded and the achievement degree of root canal preparation was scored according to our criteria. Statistical analysis of the times was performed using one-way analysis of variance (ANOVA). A value of p < 0.01 was considered significant.
  
  
  RESULTS
  Root canals were prepared using laser irradiation at 50% of teeth in G 1 and 40% in G 2. Remnant pulp tissue after laser irradiation was observed at 30% of teeth in G 1, but not recognized in G 2. Irradiated areas were scale-like and clean, but rough and irregular by FE-SEM. The statistical analysis revealed that the time required for preparation at high energies was significantly shorter compared with that at low energies (p < 0.01).
  
  
  CONCLUSIONS
  These results suggest that Er:YAG laser irradiation is capable of root canal preparation if appropriate parameters are selected.
authors.affiliation: Department of Endodontics, Showa University School of Dentistry, Tokyo, Japan. emi@senzoku.showa-u.ac.jp
authors.forename: E
authors.initials: E
authors.lastname: Matsuoka
authors.forename: K
authors.initials: K
authors.lastname: Yonaga
authors.forename: J
authors.initials: J
authors.lastname: Kinoshita
authors.forename: Y
authors.initials: Y
authors.lastname: Kimura
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D003786:Dental Pulp Cavity / Q000528:radiation effects* / Q000648:ultrastructure; D005240:Feasibility Studies; D006488:Hemostasis, Surgical; D006801:Humans; D053685:Laser Therapy; D011829:Radiation Dosage