title: Transient effects of low-energy CO2 laser irradiation on dentinal impedance: implications for treatment of hypersensitive teeth.
abstract: This study evaluated the effect of CO2 laser irradiation on dentinal impedance by passing known cyclic potentials across dentinal wafers mounted as a window in an electrolytic cell and measuring the resulting electrical impedance. Wafers were equilibrated in 0.1 M of KCl. The wafer specimens were irradiated with a CO2 laser (12 W, 0.1 ms, energy density 1.25 J/cm2). The time for impedance equilibration after irradiation was compared with equilibration after mounting. Mounted samples required 48 h to approach equilibrium in the electrolyte. After laser irradiation, impedance of previously equilibrated samples also required 48 h to equilibrate. This, along with exponential curve fitting, confirmed that laser treatment reintroduced a transient alteration in impedance. Equilibration time after irradiation and the mounting were similar. Dentin desociation apparently caused this transient impedance. Energy dispersive X-ray analysis confirmed the disappearance of K+Cl- after irradiation. Therefore, laser irradiation may cause dentinal desociation, yielding temporary clinical relief of dentinal hypersensitivity until rehydration occurs.
authors.affiliation: Department of Endodontics, School of Dental Medicine, Cairo University, Egypt.
authors.forename: M I
authors.initials: MI
authors.lastname: Fayad
authors.forename: J M
authors.initials: JM
authors.lastname: Carter
authors.forename: C
authors.initials: C
authors.lastname: Liebow
mesh_terms: D002245:Carbon Dioxide; D002712:Chlorides / Q000032:analysis; D003804:Dentin / Q000737:chemistry / Q000528:radiation effects; D003806:Dentin Permeability / Q000528:radiation effects*; D003807:Dentin Sensitivity / Q000532:radiotherapy*; D019234:Dentinal Fluid; D003890:Desiccation; D017097:Electric Impedance; D004577:Electron Probe Microanalysis; D006801:Humans; D007834:Lasers; D011188:Potassium / Q000032:analysis
chemical_list: D002712:Chlorides; D002245:Carbon Dioxide; D011188:Potassium