title: Ablative potential of four different pulses of Er:YAG lasers and low-speed hand piece.
abstract: OBJECTIVE
  The aim of the study was to evaluate the ablation rate of caries in dentin with fluorescence-feedback controlled Er:YAG, Variable Square Pulse technology (VSPt) based Er:YAG working in different pulse durations, and steel bur.
  
  
  METHODS
  Sixty human molar teeth with caries in dentin, extracted for periodontal reasons, were selected for this study. All selected teeth were randomly divided into five groups, each containing twelve specimens: (1) group FFC, fluorescence feedback-controlled Er:YAG laser; (2) group SSP (super short pulse: 50 μs); (3) group MSP (medium short pulse; 100 μs); (4) group SP (short pulse; 300 μs); and (5) group SB, steel bur in a slow-speed hand piece. A profilometer was used to determine the volume of the ablated caries in dentin. The clinical and real ablation rates of caries in dentin were calculated. Two specimens from each experimental group were selected randomly and subjected to SEM examination.
  
  
  RESULTS
  The volumes of the ablated caries in dentin in the SSP and SB groups were statistically significantly different in comparison with other experimental groups (p<0.05). The clinical and real ablation rate of caries in dentin was the highest for the SSP group (0.15±0.05 and 0.17±0.05 mm(3)/sec, respectively) and statistically significantly different in comparison with the MSP and SB groups (p<0.05). The SB and FFC groups revealed a dentin surface with a smear layer and closed dentinal tubules on SEM micrographs. In the SSP, MSP, and SP groups, an irregular surface without a smear layer was found.
  
  
  CONCLUSIONS
  Taking into consideration the experimental conditions of the present study, SSP was the most efficient in ablation of caries in dentin, providing a smear layer-free surface with open dentinal tubules.
authors.affiliation: Department of Endodontics and Restorative Dentistry, School of Dental Medicine, Zagreb, Croatia. baraba@sfzg.hr
authors.forename: Anja
authors.initials: A
authors.lastname: Baraba
authors.forename: Tadej
authors.initials: T
authors.lastname: Perhavec
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Chieffi
authors.forename: Marco
authors.initials: M
authors.lastname: Ferrari
authors.forename: Ivica
authors.initials: I
authors.lastname: Anić
authors.forename: Ivana
authors.initials: I
authors.lastname: Miletić
mesh_terms: D003737:Dental Cavity Preparation / Q000295:instrumentation / Q000379:methods; D003743:Dental Enamel / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D028022:Low-Level Light Therapy / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000528:radiation effects / Q000648:ultrastructure; D012680:Sensitivity and Specificity