title: Laser induced explosive vapor and cavitation resulting in effective irrigation of the root canal. Part 1: a visualization study.
abstract: OBJECTIVE
  Limited information exists regarding the induction of explosive vapor and cavitation bubbles in an endodontic rinsing solution. It is also not clear whether a fiber has to be moved in the irrigation solution or can be kept stationary. No information is available on safe power settings for the use of cavitation in the root canal. This study investigates the fluid movements and the mechanism of action caused by an Er,Cr:YSGG laser in a transparent root model.
  
  
  METHODS
  Glass models with an artificial root canal (15 mm long, with a 0.06 taper and apical diameter of 400 microm) were used for visualization and registration with a high-speed imaging technique (resolution in the microsecond range) of the creation of explosive vapor bubbles with an Er,Cr:YSGG laser at pulse energies of 75, 125, and 250 mJ at 20 Hz using a 200 microm fiber (Z2 Endolase). Fluid movement was investigated by means of dyes and visualization of the explosive vapor bubbles, and as a function of pulse energy and distance of the fiber tip to the apex.
  
  
  RESULTS
  The recordings in the glass model show the creation of expanding and imploding vapor bubbles with secondary cavitation effects. Dye is flushed out of the canal and replaced by surrounding fluid. It seems not necessary to move the fiber close to the apex.
  
  
  CONCLUSIONS
  Imaging suggests that the working mechanism of an Er,Cr:YSGG laser in root canal treatment in an irrigation solution can be attributed to cavitation effects inducing high-speed fluid motion into and out the canal.
authors.affiliation: Department of Dental Materials Sciences, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, Louwesweg 1, 1066 EA Amsterdam, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Blanken
authors.forename: Roeland Jozef Gentil
authors.initials: RJ
authors.lastname: De Moor
authors.forename: Maarten
authors.initials: M
authors.lastname: Meire
authors.forename: Rudolf
authors.initials: R
authors.lastname: Verdaasdonk
mesh_terms: D003786:Dental Pulp Cavity / Q000528:radiation effects; D006801:Humans; D053844:Lasers, Solid-State; D028022:Low-Level Light Therapy / Q000379:methods*; D008953:Models, Anatomic; D012388:Root Canal Irrigants; D018915:Root Canal Preparation / Q000379:methods; D012390:Root Canal Therapy / Q000295:instrumentation / Q000379:methods*; D012680:Sensitivity and Specificity; D007507:Therapeutic Irrigation / Q000379:methods; D014835:Volatilization / Q000528:radiation effects
chemical_list: D012388:Root Canal Irrigants