title: Comparison of the antibacterial effect and smear layer removal using photon-initiated photoacoustic streaming aided irrigation versus a conventional irrigation in single-rooted canals: an in vitro study.
abstract: OBJECTIVE
  The Er:YAG laser with photon-induced photoacoustic streaming (PIPS) technique was reported to be effective in root canal disinfection. This study attempted to further investigate the antibacterial efficacy and smear layer removal ability of PIPS in comparison with conventional syringe irrigation in vitro.
  
  
  METHODS
  For antibacterial analysis, 48 single-rooted human teeth were prepared and inoculated with Enterococcus faecalis, and then divided into six groups of eight roots each. The colony-forming units (CFUs) per milliliter were determined after infection as the baseline. Then, the teeth were subjected to either PIPS plus 3% sodium hypochlorite (PIPS+NaOCl) or conventional syringe irrigation with 0.9% saline, 3% NaOCl, 17% ethylenediaminetetraacetic acid (EDTA), 0.2% chlorhexidine gluconate (CHX), or 3% NaOCl alternating with 17% EDTA. The reduction of CFUs in the individual group was determined. Additionally, scanning electron microscopy (SEM) examination of the canal walls for E. faecalis colonization was performed. For comparing the smear removal efficacy, another 48 single-rooted teeth, assigned to different groups as mentioned, were irrigated after mechanical instrumentation. The presence of a smear layer at different levels of the root canal was scored by SEM examination.
  
  
  RESULTS
  No significant differences were found in CFU reduction. No bacteria could be observed by SEM in the NaOCl, NaOCl+EDTA, and PIPS+NaOCl groups. The scores of smear layer of the NaOCl+EDTA and PIPS+NaOCl groups were significantly lower than those of the other groups in the coronal and middle third of the root canal. None of the methods can effectively remove smear layer in the apical third.
  
  
  CONCLUSIONS
  PIPS system supplied with NaOCl and conventional syringe irrigation with NaOCl+EDTA are comparable in their ability to remove E. faecalis and smear layer in single-rooted canals.
authors.affiliation: Special Department, School and Hospital of Stomatology, Beijing University, Beijing, China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Zhu
authors.forename: Xingzhe
authors.initials: X
authors.lastname: Yin
authors.forename: Jeffrey W W
authors.initials: JW
authors.lastname: Chang
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Gary S P
authors.initials: GS
authors.lastname: Cheung
authors.forename: Chengfei
authors.initials: C
authors.lastname: Zhang
mesh_terms: D058491:Bacterial Load / Q000187:drug effects; D002614:Chelating Agents / Q000627:therapeutic use; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000382:microbiology; D004203:Disinfection / Q000379:methods*; D004492:Edetic Acid / Q000627:therapeutic use; D013293:Enterococcus faecalis / Q000302:isolation & purification; D006801:Humans; D066298:In Vitro Techniques; D028022:Low-Level Light Therapy / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D061088:Photoacoustic Techniques; D012388:Root Canal Irrigants; D018915:Root Canal Preparation / Q000379:methods*; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D013234:Stem Cells; D007507:Therapeutic Irrigation / Q000379:methods*
chemical_list: D002614:Chelating Agents; D012388:Root Canal Irrigants; D004492:Edetic Acid; D012973:Sodium Hypochlorite; C010882:chlorhexidine gluconate; D002710:Chlorhexidine