Transient effects of low-energy CO2 laser irradiation on dentinal impedance: Implications for treatment of hypersensitive teeth

This study evaluated the effect, of CO2 laser irradiation on dentinal impedance by passing known cyclic potentials across deratinal 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/cm(2)). 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 desiccation apparently caused this transient impedance, Energy dispersive X-ray analysis confirmed the disappearance of K+Cl- after irradiation. Therefore, laser irradiation may cause dentinal desiccation, yielding temporary clinical relief of dentinal hypersensitivity until rehydration occurs.